GB2102877A

GB2102877A - Injection nozzle for fuel injection engines

Info

Publication number: GB2102877A
Application number: GB08123042A
Authority: GB
Inventors: Jaromir Indra
Original assignee: Vysoke Uceni Technicke V Brne
Current assignee: Vysoke Uceni Technicke V Brne
Priority date: 1981-07-25
Filing date: 1981-07-25
Publication date: 1983-02-09

Abstract

A hollow body (1) has a top cylindrical bore, conical seat (11) and at least one jet hole (12). The body accommodates a needle having top cylindrical part (23) lapped into the top cylindrical bore and conical end (21) which bears in the closed position of the nozzle against seat 11. The ratio of the square of the diameter (di) of the cylindrical part (23) to the square of the largest diameter (ds) of the conical end (21) is 1.05 to 2.5. <IMAGE>

Description

SPECIFICATION Injection nozzle for fuel injection engines The invention relates to an injection nozzle for fuel injection engines, comprising a body and a differential needle being lapped into it, and bearing by its lower conical end against a conical seat, below which at least one jet hole is provided in the body of the injection nozzle.

One of the characteristics of injection nozzles is a so called hydraulic proportion, i.e. a proportion of the quadrature or square of the diameter of the lapped cylindrical part of the differential needle in the body of the injection nozzle to the quadrature or square of the largest diameter of the lower conical end of the differential needle, by which the differential needle bears against the conical seat in the body of the injection nozzle. This hydraulic proportion of the hitherto known and produced injection nozzles is always higher than 2.5. A smaller value is not recommended because of the fact that the closing pressure of the nozzle would be too low, which would worsen the quality of the fuel spray in the last phase of the jet, and would adversely influence both smoking and specific consumption of fuel.When the hydraulic proportion is greater than 2.5, springs must be used in the jet injector, and these springs must have a high value of the constant and they usually work under a high operating stress. Both these facts cause a relative quick drop of the opening pressure of the injection nozzle during the operation of the engine; undesirable consequences of this fact are well known.

The invention aims to such a design of an injection nozzle, which may obviate the said drawbacks.

This task is solved according to the invention so, that the proportion of the quadrature of the diameter of the lapped cylindrical part of the differential needle in the body of the injection nozzle to the quadrature of the largest diameter of the lower conical end of the differential needle by which the differential needle bears against the conical seat in the body of the injection nozzle, is in the range of 1.05 to 2.5.

In order that the invention may be clearly understood and readily carried into effect, a preferred embodiment thereof is, by way of example, hereinafter more fully described and illustrated in the accompanying diagrammatic drawings in which: Figure 1 shows a section of a multi-hole injection nozzle, and Figure 2 shows a section of a lower part of a pin-injection nozzle.

In Fig. 1 a differential needle 2 is seated in a body 1 of an injection nozzle. The needle has a top cylindrical part of diameter d1 which is lapped into a top cylindrical base in the body 1 of the injection nozzle. A lower conical end 21 of the differential needle 2, the largest diameter of which is dsi bears in its closing position a frusto-conical seat 11 at the bottom of the body 1 of the injection nozzle, the top angle of which is by 0.5 to 1 smaller than the top angle of the conical end 21 of the differential needle 2. Below the conical end 21 of the differential needle 2, in the lower part of the body 1 of the injection nozzle is at least one jet hole 12. A channel 13 and an annular space 14 serve to supply fuel to the seat 11.

Fig. 2 shows a section of a lower part of an pininjection nozzle, having below the lower conical end 21 of the differential needle 2, a pin 22. The said pin 22 protrudes with clearance into a jet hole 12.

The function of the said hole-injection nozzle and pin-injection one is well known and will therefore not be more fully described here.

A research of injection nozzles, the hydraulic proportion of which was intentionally less than 2.5, proved that, because of increased dimensions of the lower conical end 21 of the differential needle 2, the dropping value of the hydraulic proportion causes a drop of pressure of fuel moving at a high speed around this lower conical end 21, acting from below onto the differential needle 2, which increases advantageously the value of the closing pressure of the injection nozzle. By decreasing the hydraulic proportion, demands upon the force of the spring in the jet injector decrease as well. The jet injector is not illustrated. The said force may be dimensioned for a lower operating stress, which secures a higher stability of the closing pressure of the jet injector during the engine operation.It was also shown that if the lower conical end 21 of the differential needle 2 is bigger, the passage losses during a fuel flow through an uncovered conical seat 11 are reduced.

Although the invention is illustrated and described with reference to one preferred embodiment thereof, it is to be expressly understood that it is in no way limited to the disclosure of such a preferred embodiment, but it is capable of numerous modifications within the scope of the appended claims.

1. An injection nozzle for fuel injection engines comprising a hollow body having a cylindrical bore, a conical seat and at least one jet hole downstream of the seat, the body accommodating a differential needle having a cylindrical part, which is lapped into the cylindrical bore, and a conical end bearing, in the closed position of the nozzle, against the seat, wherein the ratio of the square of the diameter of the lapped cylindrical part of the needle to the square of the largest diameter of the conical end of the needle is in the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Injection nozzle for fuel injection engines The invention relates to an injection nozzle for fuel injection engines, comprising a body and a differential needle being lapped into it, and bearing by its lower conical end against a conical seat, below which at least one jet hole is provided in the body of the injection nozzle. One of the characteristics of injection nozzles is a so called hydraulic proportion, i.e. a proportion of the quadrature or square of the diameter of the lapped cylindrical part of the differential needle in the body of the injection nozzle to the quadrature or square of the largest diameter of the lower conical end of the differential needle, by which the differential needle bears against the conical seat in the body of the injection nozzle. This hydraulic proportion of the hitherto known and produced injection nozzles is always higher than 2.5. A smaller value is not recommended because of the fact that the closing pressure of the nozzle would be too low, which would worsen the quality of the fuel spray in the last phase of the jet, and would adversely influence both smoking and specific consumption of fuel.When the hydraulic proportion is greater than 2.5, springs must be used in the jet injector, and these springs must have a high value of the constant and they usually work under a high operating stress. Both these facts cause a relative quick drop of the opening pressure of the injection nozzle during the operation of the engine; undesirable consequences of this fact are well known. The invention aims to such a design of an injection nozzle, which may obviate the said drawbacks. This task is solved according to the invention so, that the proportion of the quadrature of the diameter of the lapped cylindrical part of the differential needle in the body of the injection nozzle to the quadrature of the largest diameter of the lower conical end of the differential needle by which the differential needle bears against the conical seat in the body of the injection nozzle, is in the range of 1.05 to 2.5. In order that the invention may be clearly understood and readily carried into effect, a preferred embodiment thereof is, by way of example, hereinafter more fully described and illustrated in the accompanying diagrammatic drawings in which: Figure 1 shows a section of a multi-hole injection nozzle, and Figure 2 shows a section of a lower part of a pin-injection nozzle. In Fig. 1 a differential needle 2 is seated in a body 1 of an injection nozzle. The needle has a top cylindrical part of diameter d1 which is lapped into a top cylindrical base in the body 1 of the injection nozzle. A lower conical end 21 of the differential needle 2, the largest diameter of which is dsi bears in its closing position a frusto-conical seat 11 at the bottom of the body 1 of the injection nozzle, the top angle of which is by 0.5 to 1 smaller than the top angle of the conical end 21 of the differential needle 2. Below the conical end 21 of the differential needle 2, in the lower part of the body 1 of the injection nozzle is at least one jet hole 12. A channel 13 and an annular space 14 serve to supply fuel to the seat 11. Fig. 2 shows a section of a lower part of an pininjection nozzle, having below the lower conical end 21 of the differential needle 2, a pin 22. The said pin 22 protrudes with clearance into a jet hole 12. The function of the said hole-injection nozzle and pin-injection one is well known and will therefore not be more fully described here. A research of injection nozzles, the hydraulic proportion of which was intentionally less than 2.5, proved that, because of increased dimensions of the lower conical end 21 of the differential needle 2, the dropping value of the hydraulic proportion causes a drop of pressure of fuel moving at a high speed around this lower conical end 21, acting from below onto the differential needle 2, which increases advantageously the value of the closing pressure of the injection nozzle. By decreasing the hydraulic proportion, demands upon the force of the spring in the jet injector decrease as well. The jet injector is not illustrated. The said force may be dimensioned for a lower operating stress, which secures a higher stability of the closing pressure of the jet injector during the engine operation.It was also shown that if the lower conical end 21 of the differential needle 2 is bigger, the passage losses during a fuel flow through an uncovered conical seat 11 are reduced. Although the invention is illustrated and described with reference to one preferred embodiment thereof, it is to be expressly understood that it is in no way limited to the disclosure of such a preferred embodiment, but it is capable of numerous modifications within the scope of the appended claims. CLAIMS

1. An injection nozzle for fuel injection engines comprising a hollow body having a cylindrical bore, a conical seat and at least one jet hole downstream of the seat, the body accommodating a differential needle having a cylindrical part, which is lapped into the cylindrical bore, and a conical end bearing, in the closed position of the nozzle, against the seat, wherein the ratio of the square of the diameter of the lapped cylindrical part of the needle to the square of the largest diameter of the conical end of the needle is in the range of 1.05 to 2.5.

2. An injection nozzle for fuel injection engines constructed, arranged and adapted to operate substantially as herein described with reference to, and as shown in, the accompanying drawing.