CN106826578B - Grinding and flow guiding device and grinding method suitable for grinding needle valve body of high-injection-pressure oil nozzle - Google Patents

Abstract

The invention discloses a grinding and flow guiding device suitable for grinding a needle valve body of an oil nozzle with high injection pressure, which comprises a positioning pin and a flow guiding rod connected with the positioning pin; the locating pin sets up in the internal restriction guide rod removal of fuel sprayer needle valve body cavity, and the guide rod head is located fuel sprayer needle valve body orifice entrance, shelters from orifice entry the latter half fillet. A grinding method includes such steps as conventional grinding, loading in grinding guide device, grinding again, and removing the grinding guide device. The ground needle valve body of the oil nozzle further reduces the flow loss inside the oil nozzle on the aspect of the performance of the oil nozzle, obviously improves the flow coefficient, reduces the probability of cavitation erosion of the spray hole under high injection pressure, and prolongs the service life of the oil nozzle under the high injection pressure. In the process, the grindable time of the needle valve body is prolonged, and the problems that the whole grinding degree of the injection hole inlet of the needle valve body is increased and the injection holes are interfered too early along with the increase of the grinding time in the conventional grinding method are avoided.

Description

Grinding and flow guiding device and grinding method suitable for grinding needle valve body of high-injection-pressure oil nozzle

Technical Field

The invention belongs to the technical field of oil sprayer processing, and particularly relates to a grinding and flow guiding device suitable for grinding a needle valve body of an oil nozzle with high injection pressure.

Background

At present, the common liquid extrusion grinding processing principle of the needle valve body is shown in fig. 6. The needle valve body is clamped by a clamping cylinder, and the high-pressure grinding agent enters a central hole of the processed oil nozzle from the clamp and returns to the material collecting box through the pressure chamber and the spray hole. Under the action of high pressure, the grinding agent generates a certain pressure and cutting grinding agent flow to the spray hole and the pressure chamber of the oil nozzle, so that the burrs of the corner and the surface of the spray hole of the needle valve body are ground in a micro-grinding mode. And a fillet with a certain size is formed in the transition area of the spray hole and the pressure chamber through grinding.

The ZEXEL company of japan teaches that the orifice flow coefficient is related to the size of the orifice inlet fillet (transition between the orifice and the pressure chamber), and that the flow coefficient of the orifice at the acute inlet is about 0.65, and increases gradually from 0.65 to about 0.91 as the fillet increases.

The probability of cavitation inside the orifice is also related to the orifice entrance fillet. The larger the inlet fillet, the less chance of cavitation. It should be noted that as the design pressure of the fuel injector increases, cavitation caused by cavitation is stronger, which affects the atomization performance and the service life of the fuel injector.

The round angle at the inlet of the spray hole is enlarged, and the grinding amount needs to be increased. The known main method for increasing the grinding amount comprises the steps of increasing the processing pressure and prolonging the processing time, while the conventional extrusion grinding processing is limited by domestic processing equipment and levels, the extrusion deformation of the spray holes is easily caused by overhigh processing pressure or overlong processing time, and the highest flow coefficient can only reach about 0.8. On the other hand, whether extrusion grinding is qualified or not is judged mainly by detecting the flow coefficient of the needle valve body at present, and the shape formed by extruding the round angle of the inlet of the spray orifice cannot be controlled.

For designing an oil nozzle with a high injection pressure, whether the flow coefficient is improved or cavitation erosion is reduced, the grinding amount of an injection hole inlet fillet needs to be increased. The CFD calculations indicate that the orifice inlet fillet is the upper half of the orifice inlet fillet (away from the needle valve body head) that dominates the flow characteristics. However, the round angle at the inlet of the nozzle hole, which is ground by the conventional grinding method, has a small difference between the radiuses of the upper round angle and the lower round angle on the circumference, as shown in fig. 1. The common shape of the injector pressure chamber determines that the abradable space below the orifice entrance is much smaller than above the orifice. By adopting conventional grinding, when the upper half part of the circular angle of the inlet of the spray orifice is ground to be large enough, the circular angle of the lower half part of the inlet of the spray orifice is excessively ground, so that interference is generated between the inlets of the spray orifice, and the randomness of the structure is improved. The grinding method needs to be improved, the upper half round angle of the injection hole inlet is ground in a biased mode in the grinding process, and meanwhile the grinding amount of the lower half round angle (close to the head of the needle valve body) of the injection hole inlet is controlled within a certain range. The flow characteristic of the oil nozzle is improved, the interference among spray holes is avoided, and the grinding time is prolonged.

Disclosure of Invention

The invention aims to provide a grinding and flow guiding device which can effectively reduce the cavitation erosion of an oil nozzle and is suitable for grinding a needle valve body of the oil nozzle with high injection pressure aiming at the defects of the existing oil nozzle grinding technology.

In order to achieve the purpose, the invention adopts the following technical scheme:

the utility model provides a grind guiding device suitable for high injection pressure fuel sprayer needle valve body grinds which characterized in that: comprises a positioning pin and a guide rod connected with the positioning pin; the positioning pin is arranged in a cavity of the needle valve body of the oil injection nozzle to limit the guide rod to move, and the head of the guide rod is positioned at the inlet of the spray hole of the needle valve body of the oil injection nozzle to shield the fillet at the lower half part of the inlet of the spray hole.

It is further characterized in that: the head of the guide rod is a plane and is matched with the head of the needle valve body of the oil nozzle in size.

Preferably: the guide rod is in a step shape, and the diameter of the head part is smaller than that of the tail part.

The positioning pin is of a three-fork structure, and the diameter of the positioning pin is matched with the diameter of a cavity at the tail part of the needle valve body of the oil nozzle.

The grinding method of the grinding and flow guiding device suitable for grinding the needle valve body of the high-injection-pressure oil nozzle is characterized by comprising the following steps of:

(1) primary grinding: the conventional grinding adopted by the primary grinding is that the needle valve body of the oil nozzle is directly assembled on a grinding clamp, high-pressure grinding agent enters a middle hole of the needle valve body of the oil nozzle to be processed from the grinding clamp, and the spraying hole is ground through a pressure chamber and a spraying hole; grinding under the grinding pressure of 3-4MPa for 3-6S;

(2) and (3) secondary grinding: inserting the grinding and flow guiding device into the cavity of the needle valve body of the oil nozzle, wherein the head of the grinding and flow guiding device shields the fillet of the lower half part of the inlet of the jet orifice; assembling the needle valve body of the oil nozzle on a grinding fixture, feeding high-pressure grinding agent into the middle hole of the needle valve body of the oil nozzle to be processed from the grinding fixture again, and grinding the upper half part of the fillet of the inlet of the spray hole through the pressure chamber and the spray hole; the grinding pressure is 4.5MPa, and the grinding time is 35S-45S;

(3) and (3) grinding for three times: and removing the grinding and guiding device, assembling the oil nozzle needle valve body on a grinding clamp, and grinding the spray hole of the oil nozzle needle valve body by using a high-pressure grinding agent, wherein the grinding pressure is 2MPa, and the grinding time is 5-10S.

Compared with the conventional grinding method, the grinding guide device and the grinding method have positive effects on improving the performance of the oil nozzle and the processing technology. On the performance of the oil nozzle, on one hand, the internal flow loss of the oil nozzle is further reduced, the flow coefficient is obviously improved, on the other hand, cavitation erosion easily generated when the orifice inlet fillet is positioned under high injection pressure is reduced, and the service life of the oil nozzle under the high injection pressure is prolonged. In the processing technology of the oil nozzle, the grindable time of the needle valve body is prolonged, and the problems that the whole grinding degree of the inlet of the nozzle hole of the needle valve body is increased and the nozzle holes are prematurely interfered with each other due to the increase of the grinding time in the conventional grinding method are avoided.

Drawings

FIG. 1 is a schematic view of a conventional milled injector orifice inlet shape.

FIG. 2 is a schematic view of the shape of the nozzle orifice entrance of a fuel injector ground using the present invention.

Fig. 3 is a schematic view of the present invention in an assembled form.

Fig. 4 is an enlarged schematic view of the head of the present invention.

FIG. 5 is a flow chart of a process for grinding using the present invention.

FIG. 6 is a flow chart of a conventional liquid extrusion grinding process for needle valve body.

Detailed Description

As shown in fig. 3 and 4, the grinding and flow guiding device suitable for grinding the needle valve body of the high-injection-pressure oil nozzle comprises a positioning pin 1 and a flow guiding rod 2 connected with the positioning pin 1; the positioning pin 1 is arranged in a cavity of the oil nozzle needle valve body 3 to limit the guide rod 2 to move, and the head of the guide rod 2 is positioned at the inlet of the spray hole of the oil nozzle needle valve body 3 to shield the fillet at the lower half part of the spray hole inlet. The guide rod 2 is in a step shape, and the diameter of the head part is smaller than that of the tail part. The head of the guide rod 2 is a plane and is matched with the head of the needle valve body 3 of the oil nozzle in size. The positioning pin 1 is in a three-fork structure, and the diameter of the positioning pin is matched with the diameter of a cavity at the tail part of the needle valve body 3 of the oil nozzle.

As shown in fig. 5, the process flow for grinding using the present invention.

Firstly, conventionally grinding a needle valve body for the first time, wherein the conventional grinding is adopted in the primary grinding, the needle valve body of the oil nozzle is directly assembled on a grinding clamp, high-pressure grinding agent enters a middle hole of the needle valve body of the oil nozzle to be processed from the grinding clamp, and a spray hole is ground through a pressure chamber and the spray hole; grinding under 3-4MPa for 3-6S. The grinding time cannot be too long, otherwise, the lower round angle of the orifice inlet is easily too large, and the orifices are interfered prematurely.

And (3) increasing the grinding pressure to carry out secondary grinding: inserting the grinding and flow guiding device into the cavity of the needle valve body of the oil nozzle, wherein the head of the grinding and flow guiding device shields the fillet of the lower half part of the inlet of the jet orifice; assembling the needle valve body of the oil nozzle on a grinding fixture, feeding high-pressure grinding agent into the middle hole of the needle valve body of the oil nozzle to be processed from the grinding fixture again, and grinding the upper half part of the fillet of the inlet of the spray hole through the pressure chamber and the spray hole; the grinding pressure is 4.5MPa, and the grinding time is 35S-45S.

And (3) grinding for three times: the grinding and flow guiding device is removed, the oil nozzle needle valve body is assembled on a grinding clamp, the spray hole of the oil nozzle needle valve body is ground by using a high-pressure grinding agent, the grinding pressure is 2MPa, and the grinding is carried out for 5-10S, so that the smooth transition between the upper fillet and the lower fillet of the spray hole is ensured.

FIG. 2 is a schematic view showing the shape of the nozzle hole inlet of the fuel injector ground by the grinding guide device of the present invention. Compared with the conventional grinding method, the method has positive effects on improving the performance of the oil nozzle and the processing technology. On the performance of the oil nozzle, on one hand, the internal flow loss of the oil nozzle is further reduced, the flow coefficient is obviously improved, on the other hand, cavitation erosion easily generated when the orifice inlet fillet is positioned under high injection pressure is reduced, and the service life of the oil nozzle under the high injection pressure is prolonged. In the processing technology of the oil nozzle, the grindable time of the needle valve body is prolonged, and the problems that the whole grinding degree of the inlet of the nozzle hole of the needle valve body is increased and the nozzle holes are prematurely interfered with each other due to the increase of the grinding time in the conventional grinding method are avoided.

Claims (1)

1. A grinding method of a grinding and flow guiding device suitable for grinding a needle valve body of an oil nozzle with high injection pressure is disclosed, wherein the grinding and flow guiding device comprises a positioning pin and a flow guiding rod connected with the positioning pin; the positioning pin is arranged in the cavity of the needle valve body of the oil injection nozzle to limit the movement of the guide rod, and the head of the guide rod is positioned at the inlet of the spray hole of the needle valve body of the oil injection nozzle to shield the fillet at the lower half part of the inlet of the spray hole; the flow guide rod is in a step shape, and the diameter of the head part is smaller than that of the tail part; the positioning pin is of a three-fork structure, and the diameter of the positioning pin is adapted to the diameter of a cavity at the tail part of the needle valve body of the oil nozzle;

the method is characterized by comprising the following steps:

(1) primary grinding: the conventional grinding adopted by the primary grinding is that the needle valve body of the oil nozzle is directly assembled on a grinding clamp, high-pressure grinding agent enters a middle hole of the needle valve body of the oil nozzle to be processed from the grinding clamp, and the spraying hole is ground through a pressure chamber and a spraying hole; grinding under the grinding pressure of 3-4MPa for 3-6S;

(2) and (3) secondary grinding: inserting the grinding and flow guiding device into the cavity of the needle valve body of the oil nozzle, wherein the head of the grinding and flow guiding device shields the fillet of the lower half part of the inlet of the jet orifice; assembling the needle valve body of the oil nozzle on a grinding fixture, feeding high-pressure grinding agent into the middle hole of the needle valve body of the oil nozzle to be processed from the grinding fixture again, and grinding the upper half part of the fillet of the inlet of the spray hole through the pressure chamber and the spray hole; the grinding pressure is 4.5MPa, and the grinding time is 35S-45S;

(3) and (3) grinding for three times: and removing the grinding and guiding device, assembling the oil nozzle needle valve body on a grinding clamp, and grinding the spray hole of the oil nozzle needle valve body by using a high-pressure grinding agent, wherein the grinding pressure is 2MPa, and the grinding time is 5-10S.

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