DE2332666A1 - FUEL INJECTOR - Google Patents

Description

Hamburg, June 21, 1973 140573 .1101

Priority: June 26, 1972, among others, Pat. 266 137

Applicant:

Caterpillar Tractor Co.

ieeoria, 111., U.S.A.

Fuel injector

The invention relates to fuel injection systems and in particular relates to an injection valve arrangement for an internal combustion engine.

Pressure ignition engines are usually with fuel injectors equipped to inject fuel into the engine's combustion chamber on a timed basis. Such Nozzles are usually through a pressure responsive shut-off valve controlled to prevent fuel from entering

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the combustion chamber trickles in between the injection strokes. To date, numerous different check valve arrangements have been proposed and used for such nozzles The known arrangements have so far always shown some disadvantages «

A simple inlet check valve is shown in U.S. Patent No. 2,410,946. There are also other types of valve arrangements have become known which are intended to overcome the difficulties encountered with this simple valve.

An accumulator or accumulator type fuel nozzle assembly is for example in U.S. Patent Nos. 2,985,378 and 2,556 described. These types of fuel nozzle assemblies have the disadvantage that they are complicated because they require at least two check valves to control the inlet and outlet of the collector chamber,

One type of fuel nozzle preferred for ease of operation has the differential area shut-off valve, which is described, for example, in [JS-j. ^j 3 2 379 399, 2 365 and 3 224 684 is shown. The main difficulty with this type of fuel nozzle and valve arrangement is that there must be a plunger pressure cannon into which the valve stem must extend so that there is a low pressure as opposed to an actuation pressure: and there is the pressure differential necessary to achieve that Operate valve »With such valve arrangements

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it is to be expected that on the valve stem to the low pressure chamber towards liquid leaking and that the valve will block as a result if the liquid from the low pressure chamber is not discharged back into a container or other location.

It is common to use such differential valves in conjunction with a fuel leakage device connected to the nozzle assembly to return the leaking fuel to the tank · The main difficulty This arrangement is that it complicates the installation and removal works by the fact that each nozzle means is provided with additional lines, which are removed and reattached when changing a nozzle v / Grounding · This not only increases the chance of leakage occurring, but also increases the extent and considerably increases the complexity of the nozzle device itself

Attempts have been made to solve this problem by having a drainage channel for the Leo fuel immediately on Inlet manifold of the engine is provided. This arrangement is described, for example, in U.S. Patent 3,382,851. Through this However, among other things, the dizziness of an increased emission of smoke and hydrocarbons can be reduced from the engine, and carbon deposits may be caused in the intake valve.

Another solution is proposed in US-Po 3 598 314

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but it is also fraught with problems. A major difficulty with this arrangement is that the collector chamber for the leak fuel in some In some cases, e.g. when starting the engine. While starting the engine before normal In injection strokes, the fuel in the valve chamber tends to remain under pressure, so that thereby significantly more fuel can leak into the accumulator chamber. This BS related to fuel leakage with the insufficient volume of the accumulator chamber leads to a cumulative pressure build-up, whereby a hydraulic blockage of the device is caused.

The last-described arrangement also prevents the use of a normal method of locking the Valve opening pressure. The usual method of locking the fuel wire to get the correct pressure for the valve opening ensure is carried out in such a way that a hydraulic pressure source is connected to the nozzle and the pressure is slowly increased until the valve opens. The opening pressure is measured in a hydraulic test circuit indicated by a pressure gauge · The slow build-up of fuel pressure within the valve chamber allows however, that a larger amount of fuel in that proportionately small header chamber of the system leaks, so that the fuel trapped in the header chamber to a hydraulic blooming that leads to the opening of the valve

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prevented.

The invention "therefore aims to provide a fuel nozzle arrangement of the differential type, in which those discussed here Difficulties of the prior art are overcome.

The invention also aims to be simple and cheap To create a fuel nozzle arrangement in which the Leokprobleme of the prior art are eliminated

Another purpose of the invention is to provide a fuel nozzle means from the differential area type in which the fuel-blocking shall find difficulties of known devices eliminates ■

According to the invention, a propellant nozzle device is equipped with a leak collecting chamber which surrounds the nozzle device and has sufficient capacity for an extended starting process is "the inventive device makes complicated Abzugaleitungen unnecessary and avoids the occurring in known devices Plüss_gkeitsblockieren _e

./ Further advantages and features of the invention result from the claims and from the following description

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and the drawing in which the invention is explained in detail and is shown "

The single figure shows a section through a preferred embodiment of a device according to the invention β

A fuel injection system embodying the invention 10 is used in connection with a cylinder head 11 which is provided with an elongated cylindrical bore 12 istβ The bore 12 has a conical extension 13 formed, which via an opening 14 with a not shown Combustion chamber communicates “The opposite The end of the bore 12 is provided with a counterbore 15 which receives a sealing element 16 and one inward from the counterbore lying threaded section 17 provided «A threaded retaining nut 18 is used to connect a fuel supply line 19 and this and to hold a nozzle arrangement in place »

The fuel injector further includes a fuel injector assembly 20 that extends into the bore 12 of the cylinder head 11 is inserted. All components the injection nozzle device 20 are enclosed in a hollow cylindrical housing 21 with a conical Section 22 is formed at its lower end «The section 22 is in sealing contact with the conical Section 13 of the bore »The housing 21 is on his upper end with an inwardly directed lip 23

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formed to hold the various components of the device in the housing. Sine Leak Collection Chamber 55 is through the annular gap between the housing 21, the outer surface of the Hanschabschnittes of Fuel-jiäinlaßleitung 19 »of the retaining nut 18 and the Wall of the bore 12 formed · This chamber is also limited by the seal that the conical hatch 22 forms with the conical Hache 13, and finally through the sealing effect of the seal 16

The nozzle device has a nozzle tip 24 »a socket 25 »a stop member 26 and a nut 27, which are stacked in the housing 21 and abut one another are arranged, wherein the nozzle tip lies within the conical section 22 · The nozzle tip 24 is cylindrical with a Bore 28 and a conical valve seat 29 formed which are concentric to a channel 30, connected to the several dispensing openings 30a, which are located at the outlet end of the channel. The tip or the exit end the nozzle protrudes into a combustion chamber of an engine in order to dispense metered amounts of fuel into it

A valve chamber 31 consists of an axial bore 32 in the socket 25 and a conical recess 33, which in the nozzle tip 24 is formed · line conical recess or low pressure chamber 35 is formed by a conical stop surface 34 of the sole member 26 limited

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The Niederdruckkamiiier 35 »which by the conical stop or Support surface 34 is formed, is about an e axial Channel 34a and a radially extending channel 36 in connection with a singing channel 37 »on the circumference of the stop member 26 is formed. The stop member 26 is so 'arranged that the annular groove 37 in connection with an outlet opening 38 of the housing 21, the opening 38 leading into the chamber 55 · A cut 39 is formed at the upper end of the stop member 26 and is in communication with the valve chamber 31 via a or several longitudinal channels 40

The nut 27 is provided with an axially extending threaded bore 41 which has a threaded connection piece 42 of the supply line 19 · A counterbore 43 is adjacent to the recess 39 of the stop member 26 and accommodates a filter 44 for filtering the fuel supplied

In the valve chamber 31, a needle valve 45 is arranged with a guide portion 46 and on its upper End is formed with a stop surface 47, which reached into the chamber 35. The needle valve has furthermore an enlarged lower section 48, from which a calf end with a conical seat surface 49 extends downward. This arrangement is referred to as an inwardly opening valve. The seat £ 9 of the needle valve is in the normal closed position of the

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Valve on the valve seat 29 of the nozzle tip 24. The lifting stop surface 47 occurs with the conical contact surface 54 in the stop member 26 in contact when the needle valve is in full open position "

A guide collar 50 is provided with an axial bore 51 which fits snugly and slidably on the miter portion 46 of the needle valve 45. A spherical bearing surface 52 is formed at the upper end of the guide collar and rests on the conical stop surface 34 of the stop member 26, whereby a self-aligning arrangement is created for the valve 45. A washer 53 is arranged on the load valve stem 45 in contact with the enlarged section 48. A leather 54 sits between the miter collar 50 and the disk 53t in ^{order to keep} the spherical surface 52 in sealing contact with the stop surface 34 and to elastically bias the seat surface 49 of the wheel valve 45 to the seat contact with the valve seat 29.

The retaining nut 18 takes care of the thread engagement the threaded section 17 in the cylinder head 11 ensures that the fuel injection nozzle 20 is fixed in the cylinder head and the seal on the conical section 22 of the nozzle 20 and on the top and bottom of the splash section the supply line 19 -is guaranteed. The seal 16, ax sits in the counterbore 15 of the cylinder headea, seals ; ■: ./ punch this counter-hole and the outer unifang of the

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Mother 18.

The following are notes in addition to the above detailed explanations of the operation of the invention Facility given.

A fuel injection pump, not shown, intermittently develops a fuel pressure which is delivered through the supply line 19, the filter device 44, the recess 39 and the channel 40 into the valve chamber 31. At the beginning of an injection cycle, the needle valve 45 sits on the valve seat 29. When the fuel pressure develops, it acts on an area which is equal to the cross-sectional area of the guide section of the valve 45 minus the effective seat area of the needle valve »This hydraulic force exerts because of the differential areas exerts a net upward force on needle valve 45 seeking to lift it off the seat or open it inward. The door tension of the spring 54 counteracts this force. When the fuel pressure reaches the level required to exert a force equal to the predetermined spring force, the needle valve 45 lifts off, the seat surface 49 being moved away from the valve seat 29. This allows fuel to flow into the channel 3C and from there through the mouths 30a of the nozzle tip 24. The fuel pressure then exerts an upward force on the entire cross-sectional area of the driving section of the shut-off valve 45 and produces a faster one

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Upward movement of the shut-off valve 45 »so that a "Sudden effect" results. The needle valve etst its upward movement continued, ice the lifting sole surface 47 pushes against the surface 34 in the stop member 26

Driving the periods in which a fuel pressure is in the chamber 31 is present, leakage occurs Fuel between the slidingly matching menu 46 of the needle valve 45 and the bore 51 of the guide collar 50. The leaking miscarriage goes through the low pressure chamber 35 »the channels 34a and 36 and the annular groove 37 therethrough and is through the outlet opening 38 into the S annular leak collection chamber 55 submitted. This collection chamber has essentially the same longitudinal dimension as the main valve elements the Dtiseneinriohtung. This leads to a more crowded one Arrangement of the valve device and the Leok container. In addition, this construction enables the low pressure chamber is only made as large as is necessary to accommodate the movement of the valve member, while the annular plenum chamber exceeds the volume of the low pressure chamber by a sufficient size, to pick up Leok fuel. The annular collecting chamber can also be easily enlarged by that simply the cylindrical bore is enlarged without any other changes to the fuel nozzle assembly will be required.

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For a longer period of time, the single chamber becomes with Fuel filled, the pressure in the chambers 55 and 55 and the connection channels change during each cycle the pressure development in the chamber 31 is increased by an amount, that directly through the amount of leakage, the upward shift of the needle valve, the compressive modulus of elasticity of the fuel and vice versa by the combined Volume of the aforementioned chambers and channels is determined · Since the total volume of the chambers and ducts is proportional is large, the pressure increase therein during each pressure development cycle in the chamber 31 is proportionate small · Because of the relatively small pressure build-up in the chamber 35, the chamber 55 and the connecting channels, a normal working sequence in the fuel nozzle becomes guaranteed before hydraulic jamming can occur «

During normal operation in the fuel nozzle, the pressure in the chamber 31 decreases as the development the fuel pressure from the fuel pump has ended. This is due to the fact that fuel through the Discharge openings 30a flows and furthermore also in the usual way duroh the feed line 19 flows back to the pump. When the fuel pressure has decreased sufficiently, the spring 54 pushes the needle valve 45 downward and causes that the seat surface 49 rests on the valve seat 29. Since the pressure of the fuel in chambers 35 and 55 and in the connection channels then larger than the printout in the

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Valve chamber 31, leakage occurs in the reverse direction into the valve chamber and decreases the pressure in the aforementioned chambers and channels. After a certain number of injection processes, the Average pressure that prevails in the wrestling chamber Equilibrium "at which the same amount leaks in and out of the chamber. Because of this balance weight flow there is no hydraulic blocking of the "valve.

- PATENT CLAIMS -

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Claims (5)

PATENTAFSPRuO-HB 1.) Fuel injector, with a through Differential pressure controlled fuel nozzle and with means for receiving leaking fuel, daduroh characterized in that a housing (21) has a central valve chamber (31) and a valve chamber surrounding the valve chamber, limited annular leak collection chamber (55) and an inwardly opening valve member (45) which, by its action, permits the escape of liquid from the valve chamber and a nozzle opening (30, 30a) adjoining this and controls a first, from the pressurized liquid in the valve chamber acted upon surface area and one opposite has a lying surface area on which the liquid acts in a low-pressure chamber (35), with the leakage chamber in connection (34a, 36> 38) stands. 2. Device according to claim 1 arranged on a cylinder of an internal combustion engine, characterized in that that in the cylinder head (11) a bore (12, 13) is formed which is in open communication with the combustion chamber stands and the wall of which forms the outer wall of the Leoka collection chamber (55), the inner wall of which forms the Outside of the housing (21) arranged concentrically in the bore 1st. 309883/0555 3. Device according to claim 1 - 2, characterized in that that · the ring-shaped oil collecting chamber (55) encompasses the space the volume of the low-pressure chamber (35) exceeds 4 · Device according to claims 1-3 »characterized in that the length of the Leok collection chamber (§5) is essentially is the same as that of the housing (21) of the valve assembly 5. Device according to claim 1 - 4, characterized in that that to limit the Leok collection chamber (55) at each end of the housing (21) sealing means (22, 13J 16, 17 » 18, 19, 23) are provided. 6 · Device according to one of the preceding claims » characterized in that the valve chamber (3,1) and the low-pressure chamber (35) duroh one the valve element (45) leading device (50) are separated, which has a Buohse, which at one end with a spherical Bearing surface (52) is formed and in which the valve element is arranged to be movable back and forth, a conical bearing surface (34) being provided in the housing (21) for receiving the spherical surface and a spring device (54) is disposed between the valve element and the socket and the bearing flanges in engagement $ 309883/055 Blank page