GB2052630A

GB2052630A - Fuel Injection Valve Fuel Discharge Passages

Info

Publication number: GB2052630A
Application number: GB8016847A
Authority: GB
Original assignee: Daimler Benz AG
Current assignee: Daimler Benz AG
Priority date: 1979-05-26
Filing date: 1980-05-21
Publication date: 1981-01-28
Also published as: FR2457988A1; DE2921455A1; IT8048779A0; IT1127855B

Abstract

The outlet passage 4 downstream of the valve seat 3 has a discontinuity formed by a conical or stepped cylindrical enlargement of the downstream passage portion 4b. The discontinuity causes fuel flow detachment to prevent the formation of carbon deposits. The passage 4 may be formed in the valve pintle 6, Figures 5 and 6 (not shown). <IMAGE>

Description

SPECIFICATION Fuel-injection Valves The invention relates to fuel-injection valves, for air-compression fuel-injection internalcombustion engines, having a spindle which opens, lifting from its conical valve seat, in the direction opposite to the direction of fuel flow and an outlet passage which adjoins the valve seat and is non-closeable against the fuel-admission opening to the combustion chamber of the engine.

In practice, cross-sections of the outlet passage often become constricted due to carbonisation. This results in deterioration in operating characteristics of the engine.

To make the operation of fuel-injection valves more reliable, the present invention seeks to prevent or reduce carbonisation in the outlet passage, According to the invention, a fuel-injection valve, for an air-compression fuei-injection internal combustion engine comprises a spindle which opens, lifting from a conical valve seat, in a nozzle element in the direction opposite to that of the fuel flow and an outlet passage adjoining the valve seat and permanently open for communication with an opening to a combustion chamber, the wall configuration of the outlet passage comprising at least one discontinuity and/or enlargement which causes flow detachment.

The aforesaid cross-sectional configuration of the outlet passage in the direction of flow causes cavitation to occur which carries away carbonisation residues or prevents deposition of such residues. However, the cavitation should only be sufficient to remove carbonisation residues, without removal of the hard nozzle material and without the form of the emerging jet of fuel being detrimentaily changed. It is also advantageous that particles of dirt cannot become wedged in the outlet passage and block it.

Embodiments of the invention by way of examples are illustrated in the accompanying drawings, in which: Figs. 1 and 2 are sections through lower parts of fuel-injection valves with throttling pintles, showing different forms of nozzle-outlet passages, Figs. 3 and 4 are similar sections for valves without throttling pintles, again showing different forms of nozzle-outlet passages, and Figs. 5 and 6 are similar sections through valves with pintles having outlet passages of different forms.

All of the valves illustrated are fuel-injection valves 1, for air-compression fuel-injection internal-combustion engines, comprising a nozzle element 2, a conical valve seat 3 therein, an outlet passage 4 for open communication with the combustion space and a spindle or needle 5.

The Injection valves 1 of Figs. 1 and 2 are of the kind having a nozzle in which a throttling pintle or spigot 6 on the spindle 5 projects into the outlet passage 4 located in the nozzle element 2, the fuel being discharged around the pintle. The passage 4 comprises two sections, of which a section 4a downstream of the valve seat 3 with respect to the direction of fuel flow is of cylindrical form and a section 4b adjoining it is of conically widening form in Fig. 1, thus forming a discontinuity at the transition between the said sections. The section 4b in Fig. 2 is of cylindrical form, but of larger diameter than the section 4a.

The transition between the two cylindrical sections 4a and 4b affording a discontinuity is in the form of a sharp-edged step 7 in this case.

The injection valves 1 of Figs. 3 and 4 are of the kind in which the fuel is discharged from an orifice into which no pintle extends. The spindle 5 terminates in a point 8 and, in the closed position of the valve, the point merely dips into the cylindrical section 4a of the outlet passage 4. In Fig. 3, the wider section 4b of the passage is of conical form, as in Fig. 1. In Fig. 4, the outlet passage 4 has a sharp-edged step 7, the section 4b being of cylindrical form, as in Fig. 2.

The injection valves 1 of Figs. 5 and 6 are of the kind in which the fuel is discharged from an orifice in the pintle 6. The pintle has a transverse through bore 9 opening into an annular space 8 below the valve seat 3 and a central axial bore, branched from the bore 9, which constitutes the only fuel-outlet passage 4. The passage 4 located centrally in the pintle 6, again comprises a first, cylindrical, section 4a, which is adjoined by either a conically widening section 4b (Fig. 5) or by a second cylindrical section 4b which is wider beyond a sharp-edged step 7 (Fig. 6).

In all cases, the outlet passages are widened, in the direction of flow, by such a small amount only that the flow does not become detached or only partially so, by venturi action or becomes reattached after detachment.

Claims

1. A fuel-injection valve, for an air-compression fuel-injection internal combustion engine, comprising a spindle which opens, lifting from a conical valve seat, in a nozzle element in the direction opposite to that of the fuel flow and an outlet passage adjoining the valve seat and permanently open for communication with an opening to a combustion chamber, the wall configuration of the outlet passage comprising at least one discontinuity and/or enlargement which causes flow detachment.

2. A valve according to claim 1, wherein the outlet passage has a cylindrical section which is adjoined downstream at a sharp-edged transition by a wider cylindrical section.

3. A valve according to claim 1 , wherein the outlet passage has a cylindrical section which is adjoined downstream by a conically widening section.

4. A valve according to any one of the foregoing claims, which is a valve of the kind comprising a throttling pintle having an orifice in

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Fuel-injection Valves The invention relates to fuel-injection valves, for air-compression fuel-injection internalcombustion engines, having a spindle which opens, lifting from its conical valve seat, in the direction opposite to the direction of fuel flow and an outlet passage which adjoins the valve seat and is non-closeable against the fuel-admission opening to the combustion chamber of the engine. In practice, cross-sections of the outlet passage often become constricted due to carbonisation. This results in deterioration in operating characteristics of the engine. To make the operation of fuel-injection valves more reliable, the present invention seeks to prevent or reduce carbonisation in the outlet passage, According to the invention, a fuel-injection valve, for an air-compression fuei-injection internal combustion engine comprises a spindle which opens, lifting from a conical valve seat, in a nozzle element in the direction opposite to that of the fuel flow and an outlet passage adjoining the valve seat and permanently open for communication with an opening to a combustion chamber, the wall configuration of the outlet passage comprising at least one discontinuity and/or enlargement which causes flow detachment. The aforesaid cross-sectional configuration of the outlet passage in the direction of flow causes cavitation to occur which carries away carbonisation residues or prevents deposition of such residues. However, the cavitation should only be sufficient to remove carbonisation residues, without removal of the hard nozzle material and without the form of the emerging jet of fuel being detrimentaily changed. It is also advantageous that particles of dirt cannot become wedged in the outlet passage and block it. Embodiments of the invention by way of examples are illustrated in the accompanying drawings, in which: Figs. 1 and 2 are sections through lower parts of fuel-injection valves with throttling pintles, showing different forms of nozzle-outlet passages, Figs. 3 and 4 are similar sections for valves without throttling pintles, again showing different forms of nozzle-outlet passages, and Figs. 5 and 6 are similar sections through valves with pintles having outlet passages of different forms. All of the valves illustrated are fuel-injection valves 1, for air-compression fuel-injection internal-combustion engines, comprising a nozzle element 2, a conical valve seat 3 therein, an outlet passage 4 for open communication with the combustion space and a spindle or needle 5. The Injection valves 1 of Figs. 1 and 2 are of the kind having a nozzle in which a throttling pintle or spigot 6 on the spindle 5 projects into the outlet passage 4 located in the nozzle element 2, the fuel being discharged around the pintle. The passage 4 comprises two sections, of which a section 4a downstream of the valve seat 3 with respect to the direction of fuel flow is of cylindrical form and a section 4b adjoining it is of conically widening form in Fig. 1, thus forming a discontinuity at the transition between the said sections. The section 4b in Fig. 2 is of cylindrical form, but of larger diameter than the section 4a. The transition between the two cylindrical sections 4a and 4b affording a discontinuity is in the form of a sharp-edged step 7 in this case. The injection valves 1 of Figs. 3 and 4 are of the kind in which the fuel is discharged from an orifice into which no pintle extends. The spindle 5 terminates in a point 8 and, in the closed position of the valve, the point merely dips into the cylindrical section 4a of the outlet passage 4. In Fig. 3, the wider section 4b of the passage is of conical form, as in Fig. 1. In Fig. 4, the outlet passage 4 has a sharp-edged step 7, the section 4b being of cylindrical form, as in Fig. 2. The injection valves 1 of Figs. 5 and 6 are of the kind in which the fuel is discharged from an orifice in the pintle 6. The pintle has a transverse through bore 9 opening into an annular space 8 below the valve seat 3 and a central axial bore, branched from the bore 9, which constitutes the only fuel-outlet passage 4. The passage 4 located centrally in the pintle 6, again comprises a first, cylindrical, section 4a, which is adjoined by either a conically widening section 4b (Fig. 5) or by a second cylindrical section 4b which is wider beyond a sharp-edged step 7 (Fig. 6). In all cases, the outlet passages are widened, in the direction of flow, by such a small amount only that the flow does not become detached or only partially so, by venturi action or becomes reattached after detachment. Claims

4. A valve according to any one of the foregoing claims, which is a valve of the kind comprising a throttling pintle having an orifice in the nozzle element downstream of the valve seat, which orifice constitutes the outlet passage.

5. A valve according to any one of the foregoing claims, wherein the valve is of the kind having a pintle with an orifice and a transverse bore opening into an annular space downstream of the valve seat and a central axial bore branched from the said transverse bore and constituting the outlet passage.

6. A fuel-injection valve substantially as hereinbefore described with reference to any of the figures of the accompanying drawings.