DE2159402A1 - Liquid fuel injection pumps for internal combustion engines - Google Patents

Description

INSIH ¹ UT PRANOAIS DU PETROiE- I) ES CARBtTRAlTTS Ει LUBRIF! AMTS

HUEII-MALMAISOIJ / Prankr e i oh

Liquid fuel injection pumps for internal combustion engines .

The invention relates to liquid fuel injectors Injection pumps for internal combustion engines »

In particular, the invention is directed to Einapritzpurapen with a piston slidable in a cylinder, the bottom of the cylinder having a delivery opening connected to an injection channel for the fuel and the side wall of the cylinder having at least one opening

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which simultaneously serves to feed the cylinder with fuel and to discharge the fuel at the end of injection, this opening being exposed by the upper edge of the solenoid when it is in the position furthest from the bottom of the cylinder and by the side wall of the piston is closed when the piston approaches the bottom of the cylinder in the injection position.

The piston of the pump comprises at a certain distance from its head an inclined relative to the axis of the piston Ramp or opening, this ramp forming the upper edge of a groove; the one with the space between the head of the piston and communicates with the bottom of the cylinder, this ramp controlling the end of injection when it is the inlet port happens during the upstroke of the piston »

Under certain conditions, the opening also serves as an inlet and outlet opening _{or similar}

The invention thus relates to no Pail on injection pump ^ in which the fuel supply to the cylinder of the pump and its outlet at the end of injection via different Openings take place =

In certain cases of use, the injection pump can close Lead cavitation phenomena, which cause erosion of the pump body and the injection channels.

Cavitation is the result of a sudden drop in pressure of the fuel at the end of injection, when this pressure falls below the vapor tension of the fuel. It is formed then fuel bubbles in the injection lines, which are destroyed when the pressure waves pass through

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and whose freigesetae energy is sufficient on the metallic To pick up walls *

Alternatively, the Bmclischvringung germ _t (afterdrip) to the sudden reduction of pressure in the fuel pump Drnckkantser _f follows to re-open the Einspritznädel and thus to an undesirable SaLtundäreinspritEung- lead.

Also should erfindungsge'-iiäß pump oißeschlagen ^ t-Jerden, where, with a Si outdoors- Einspri1.sl> eginns _f ee möglieh vird _s ohersteliung a very significant reduction öes pressure of the fuel in the cylinder of the pump-in. Injections end too old, "νίε ^ ο drips leads to the fact that the disturbing ravitation or injection phenomena are flawed or at least as far as possible.

■ In other cases Tervje η manure it is desirable to have below a Pu'npe _f the progressive increase in pressure in 'ZylinäQX the pump at ensuring Einspritsboginn.

This is achieved according to the invention. that "the .or)! Dinlaßöffnungen NSIT to äev an elongated JPorm two substantially parallel edges gives whose direction forms an angle with the axis of the Pu'-npenkolbens, liach a first" Ausftihrungsform that allows ,, as far as possible " The edges of this opening are essentially parallel to the upper edge of the piston of the pump, '

Obtained sii Kqch another embodiment, allowing a gradual pressure increase in _s Einspritssbegimi ,, rind αϊG edges of this opening to the ^{top: i} R'änd f'ies KolbGiiß clex ¹ pump inclined.

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According to this second embodiment, if the Cavitation phenomena are not to be feared, the edges of this opening are essentially parallel to the upper one Be the edge of this ramp of the piston and the interruption control the injection, which allows a free To get injection end.

Exemplary embodiments of the invention are intended will now be explained in more detail with reference to the accompanying drawings, in which

Pig. 1 is an entire illustration of the pump;

Mg «2, 3 and 4 follow the working principle of a pump explain the invention and each of the suction phase of the fuel in the pump, which the The delivery phase initiating the injection of this fuel into the engine and the end of injection demonstrate;

the pig. 5 and 6 show the raltiven in a larger representation Positions of piston and inlet opening during the intake phase and at the end of injection;

and Figs. 7 and 8 show another embodiment of the invention, the relative positions of the piston at the start of injection and after the end of injection are shown.

The one in Pig. 1 shown Purapenkürper comprises in. Its Housing 1 provided with a recess in the lower part

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in which with little play a Stöeael 2 slidably slid is to which the axis 3 of a hollow 4 is rigidly assigned is. The hell so firmly attached to the pestle. 4-support look at the girth of the Nooke 5 because of the power which is exerted on the plunger by the spring 6 » which is supported against the capsule 7, which in turn is the Piston rod end θ of the piston 9 in direct contact with takes the ram with it.

The groove limited by the ramp 11a in the upper part 11 provided head of the piston 10 slides in a cylinder shirt 13, which is pierced by a fuel feed opening 1.4, which connects the inside of the cylinder shirt with a pantry. The liquid fuel introduced into the liner is conveyed through the piston into the compression chamber 16, which is in communication with this liner standsι where the pressure is tared by means of the spring 18 Flap 17 is maintained.

Sine provided in the piston 10 axial line 12, which against the upper part of which is open »sets chamber 16 with it the hat 11 in connection.

When the pressure exerted by the liquid in the compression chamber 16 on the underside of the valve 17 The force is greater than the force that acts on the top of the valve (lUarierungakraft the spring 18 of the valve flap and residual pressure in the injection line), so flows the fuel into the chamber 19, where the spring 18 is and from there via the connecting channel 20 into the Injection pipe 21.

The chamber 19 is due to the internal weight of a clamping head and the seat 23 of the valve 17 is limited

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rests against the:. circular ring-shaped shoulder 24, the Inner wall of the clamping head it. The chamber 19 is free with the channel 20 in connection, which is also provided in the clamping head, the upper part of which is otherwise with a Recess provided iat as a bearing for the approach 25 to serve the injection line «This approach 25 * der is held by the clamping attachment 26, serves to firmly connect the injection line to the clamping head 22, which in turn is rigidly attached to the housing 1.

Figs. 2 to 6 explain the operation of the pump according to the invention.

If, during the rotation of the nooke 5, the head 10a of the Piston 10 exposes the inlet opening 14 (fig. 2 and 5), so the supply of liquid from the pantry takes place originating fuel in the cylinder of the pump *

The elongated shape of the suction or inlet opening 14 in an injection pump according to the invention allows for the fuel has a relatively large diameter cross-section, This ensures sufficient filling of the cylinder of the pump despite a low feed pressure of the fuel results.

The rotation of the squat ^c> continued (Pig "3) ao closes the piston 10 of the Puape, while it approaches the bottom of the cylinder, the inlet opening 14 and the fuel is then driven against the compression chamber 16 via the feed port 16a and from there forced into the inlet line 21 under pressure.

While the KolbmiO se continues its upward stroke, the Rmmpe 11a exposes the inlet opening 14 (Figs. 4 and 6). In these"

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_ 7 -

Momentarily the space between the bottom of the cylinder of the pump and the head of the piston is set in connection with the storage chamber 15 via the groove 11 and the axial line 12, which means that the injection into the chamber 19 is interrupted by a pressure drop in the fuel in the ver 'the control chamber 16 provides.

By making the inlet opening 14 an elongated shape, preferably at an angle with that of the Raape 11 (the opening 14 is elongated parallel to the top 10 ^ of the piston in the illustrated Ausftthrungsform) one achieves that the groove 11 of the piston very gradually came into contact with this opening will ο

During the upstroke of the piston which is (Fig. 6) starts the ramp i'la the opening 14 in the Liage 11a expose '- indicated in dotted lines - and the opening 14 is only exposed when the ramp 11a, the situation has reached 11 ^w _t In order to open the opening completely, a total displacement H (FIG. 6) of the piston of the pump is required, this displacement being considerably greater than the width h (FIG. 5) of the opening 14.

This arrangement , which enables the opening 14 to be exposed very gradually, avoids a sudden reduction in the pressure of the fuel in the compression chamber 16 and also eliminates or reduces the cavitation phenomena and the dangers of parasitic injection mentioned above it comprises at least ise in considerable W _e,

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According to the execution form shown in FIGS. 7 and 8 the elongated opening 14 is against the upper edge IO of the pump piston inclined "

There, during the upward stroke of the piston, the upper edge 10 of the piston begins ^{to close the opening 14 in position 10a 1} - indicated by dash-dotted lines - and the opening is only completely closed when the upper edge of the piston has reached position 10a " Complete closing of the opening 14 thus requires a (total displacement H (Pig 7) of the pump piston, this displacement being very much greater than the width h of the opening H.

This arrangement enables a gradual increase in pressure preserved in the cylinder of the pump at the end of injection »

If there is no fear of cavitation ”so the edges of the opening H can be substantially parallel to the upper edge of the ramp 11a (Fig. 8), which makes it possible a quick opening of the opening 14 at the end of the injection to obtain * which ensures a quick interruption of the injection *

A value between 1 and 4 is preferably chosen for the ratio L of the length of the opening 14 to its width.

Claims

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Claims (2)

- 9 "claims Injection pump with a piston slidingly displaceable in a cylinder, the bottom of the cylinder having a delivery opening which is connected to a fuel injection channel and the side wall of this cylinder, at least one opening being provided in the latter which simultaneously serves to feed the cylinder with fuel and ZU ¹ Qi the fuel flows out at the end of the injection, this opening being exposed by the upper edge of the piston when it is in the position furthest away from the bottom of the cylinder and is closed by the side wall of the piston when the piston approaches the cylinder head in the injection position and the piston has a ramp inclined towards the piston neck at a certain distance from its head, this ramp forming the upper edge of a groove communicating with the space between the piston head and the cylinder head and this ramp controlling the injection interruption , you rch characterized in that this inlet opening (14) is elongated in shape with two substantially parallel edges, the direction of which forms an angle to the axis of the pump piston {10). 2. Injection pump according to claim 1, characterized in that the edges of this opening (H) are essentially run parallel to the upper edge of the piston (10) of the pump * ; 5. Injection pump according to claim 1, characterized in that that the Handel * of this opening (14) against the upper edge 209825/0764 ~ ίο - of the pump piston ^ (10) are inclined., 4. Injection purapa according to claim 1, characterized in that the edges of the opening (14) are essentially parallel to the upper edge of this chamber which controls the injection interruption or the end of injection, 5, injection pump according to claim 1, characterized in that that the ratio (L) of the length of this inlet opening (14) on its width is between 1 and 4. 20982 5/0764 BAD ORIGINAL