Delivery valve for fuel injection pumps.

p0001The invention is based on a pressure valve according to the preamble of the main claim. One such known by the AT-PS 334 695 pressure valve has a cup-shaped valve closing member, wherein the end face at the open end of the cup-shaped valve closing member ist.und formed as a sealing surface the valve closing member is guided in a tubular valve body and there on the injection pump side end of a diameter constriction of inner bore of the tubular valve body has a valve seat. Furthermore, the cup-shaped valve closure member in the ground to an axial bore which is controlled by the closing member of the check valve. This hole is formed not as a throttle bore. The known configuration is moreover an object to provide a tamper-proof and unsolvable from the valve body abutment for the return springs of the check valve and to prevent can reach larger parts in the pump chamber at a failure of parts of the pressure valve. For this purpose, the valve body has a continuous bottom, the ring is merely pierced to enable the fuel to kick the abutment of the compression spring of the check valve. In this embodiment, the abutment of the compression spring of the check valve is disposed in height of the seat in the valve body specifically. This configuration makes it difficult to significantly adjust the spring tension to the check valve. For this purpose, shims would have to be introduced, on the one hand reduce the flow cross-section at the bottom of the valve body and on the other hand optionally hinder the movement of the valve closure member of the pressure valve.

ADVANTAGES OF THE INVENTION

p0003The pressure valve according to the characterizing features of the main claim has the advantage that any resulting pressure fluctuations in the conduit system between the connected to the feed line fuel injection valve and the pressure valve are quickly dampened and reduced. In a known manner the actual pressure relief valve acts such that once the effective promotion of the pump piston of the fuel injection pump is completed, the connection between pump working chamber and fuel delivery is interrupted. It is thus achieved in a known manner, that the injection valve is closed immediately, without that fuel is post-injected. When closing the pressure valve and the fuel injection valve, however, occur as a result of dynamic processes on pressure oscillations in the delivery line system, which, if they are not quickly attenuated, exhibit pressure peaks, which can open the valve needle of the fuel injector again, so that in turn also fuel is post-injected. However, where the pressure valve does not completely or at least not at first completely, these pressure waves can be quickly degraded effectively, so that a dripping of fuel is avoided. With the help of the check valve is, however, obtained a constant residual pressure in the conduit system between the injection valve and pressure valve to prevent combustion gases from entering the injector during the injection pauses. If the check valve is missing, so the pressure in the pipe system during the intake stroke of the pump piston can be significantly reduced, so that combustion gases could enter the Leitunssystem. These gases would significantly distort each per cycle fuel quantity and also damage the injector. By inventively provided throttle in addition to the above-described operations of the pressure valve of the invention is achieved that on the one hand, a constant static pressure is maintained in the feed pipe system during the injection pauses and on the other hand pressure oscillations, which would lead to post-injection of fuel, are rapidly degraded via the throttle. A secure closure is required in particular for the supply of high-speed Direkteinspritzerbrennkraftmaschinen. It is achieved at a constant stroke injection start with the least amount of scattering of stroke.

p0004By embodiments according to dependent claims 2 to 4 results in a cost-effective design of the pressure valve, the mount easily and relying pressure slightly on the bias of the compression spring of the check valve can be adjusted. Advantageously allows the configuration of the valve closing member according to claim 4 easy insertion of shims to adjust the preload.

p0005The embodiment according to dependent claim 5 further has the very considerable advantage that the valve body has a very easy to produce form, can easily be assembled with the connecting piece and provides the opportunity to accurately adjust the opening pressure of the check valve in the assembled state of the pressure valve, in the controlled the sleeve is more or less far pressed into the cylindrical part of the valve body. With the embodiment according to claim 6, a very short slung pressure valve will be realized with easy machined sealing surfaces on the valve body and the valve closure member.

p0006The embodiment defined in dependent claim 7 has the advantage that the maximum stroke of the valve closure member can be limited and in any position of the valve closing member, the opening of the throttle bore is deteriorated. Neither by abutting against the spring plates or by accumulation of contaminants at this point

drawing

p0007Six embodiments of the invention are illustrated in the drawings and are described in more detail below. 1 shows a first embodiment with an inner collar on the valve body as an abutment for the compression spring of the check valve, Figure 2 shows a second embodiment in a modification of the embodiment of Figure 1 with spring plate and a stop for the check valve, Figure 3 shows a third embodiment in a modification of the design according to figure 2 with a designed as a flat seat valve valve closing member of the pressure valve, figure 4 shows a fourth embodiment with a pressed sleeve as an abutment of the compression spring of the check valve, figure 5 shows a modified embodiment of the embodiment of figure 4 and figure 6 shows an additional modification of the embodiment of figure 4 with a trained as a flat seat valve valve closing member of the pressure valve.

Description of Embodiments

p00081 shows a longitudinal section through a first embodiment of a pressure valve is shown, which is screwed into the housing 2 of a fuel injection pump not shown and is located in a conveying conduit 4 between the pump working space, not shown, of the fuel injection pump and an injection valve 3 of the internal combustion engine to be supplied, not shown. The pressure valve has in this case a connection piece 6 which is screwed into a threaded hole 7 of the housing. The connecting piece has an axial recess 8 which is open to Einschraubseite back and essentially has the shape of a blind hole. Coaxial with the axial recess departs from this, a terminal channel 10, which opens out in the connection nipple 11 of the connection piece and connects the axial recess to the delivery line.

p0009From the pump-side end into the axial recess 8, a tubular valve body 12 is used, the a covenant J4 at its pump end via which it is held by the pump-side end face J5 of the connection piece against a shoulder 16 of the threaded bore. 7 From the pump end of the threaded bore 7, the feed line 4 performs the pump work chamber. On projects into the axial recess 8 front end, the tubular valve body has a valve seat 17 on which a conical sealing surface 18 of a valve closure member 19 comes to rest. This comprises in a known manner on wing-shaped guide surfaces 20, which are guided in a channel formed as a through internal bore 21 of the valve body, and between which fuel can pass through the valve seat. On a projecting into the connection channel-side part of the recess 8 the shoulder 22 of the valve closure member 19 is engaged by a pressure valve spring 23, on the other hand is supported via a spring plate 24 at the connection channel-side end of the recess eighth

p0010The valve closure member 19 further includes a longitudinal channel in the form of a longitudinal bore 26 extending in axial direction of the valve closure member and in the region of the guidance of the pressure valve spring 23 serving guide pin 25 passes into a throttle bore 28 and opens out there into the axial recess eighth Pump side, the end of the longitudinal bore 26 is formed as a valve seat 29 of a check valve 30, whose valve closing member is a ball 31 is that a pressure spring 34 is clamped via a spring plate 32, between which and a Innenbund'33 of the valve body is brought into the closed position. The released through the inner collar 33 through 35, the inner bore 21 of the valve body 12 is connected to the feed line. 4

p0011The spring plate advantageously has a spherical shape of the valve closing member 31 adapted central recess 27 from which a funnel-shaped passage over at their edges 39 with a flatter profile (larger cone angle) which as shown in Fig. 1a. So that the ball 31 can be brought considerably lighter in its working position during assembly. In the same way, the cone-shaped seat 29 is designed at the valve closing member 29th

p0012If a fuel injection pump, the pressure valve of the invention is installed fuel conveyed to the internal combustion engine during operation, the valve closing member 19 is opened under the pressure of air supplied via the feed line 4 fuel. At the end of fuel delivery, the valve closing member keh.rt 19 to its valve seat back. At the same time, the injection valve closes at the end of the conveying line. Following this abrupt interruption of the promotion run in the enclosed volume between the pressure valve and injector pressure waves back and forth, which are able to at a later time for a short time to open the injector again. By the intended non-return valve in communication with the throttle bore 28 however, this is prevented. For an incoming on the valve closure member 19 pressure wave, the check valve 30 is opened as soon as the static pressure that should maintain this valve is exceeded. Here, fuel flows to a small extent back on the throttle 28th This causes delayed by pressure reduction to the set at the check valve prior pressure damping of pressure oscillations in the delivery line system. At the same time with the non-return valve, a minimum level pressure is maintained so that it is prevented that the combustion gases can reach during the subsequent to the injection operation of the injector pressure buildup in the combustion chamber in the injector and in the delivery line, would damage the valve and the precise metering of fuel per cycle would. The structure shown in Figure 1 of the pressure valve allows small dimensions and a cheap production. The parts of the pressure valve are easy to assemble, wherein the valve body and the connecting piece can be held together by a resilient clamp 36 for the transport of the pressure valve. The envisaged in the longitudinal bore 26 throttle bore 28, in a modification of the foregoing and. be arranged to the following embodiments as Rückströmdrossel in the connection to the conveying pipe 4, said throttle is switched off in known manner at the fuel delivery so that an unthrottled support is provided.

p0013The embodiment of Figure 2 is essentially the same structure as the embodiment of FIG 1. In describing the same item numbers are therefore in the matching points used. Notwithstanding shows the embodiment in Figure 2 is a hat-shaped spring plate 37 which is clamped between the compression spring 34 and inner collar 33rd The bottom of this plate spring serves as a stop for the ball 31 leading spring plate 32. In the lateral surface of the hat-shaped spring plate 37 connecting holes 38 are provided, which make the passage for the passage of the 35th This configuration has the advantage that for large opening strokes of the check valve 30 may be avoided. Due to the labyrinth-like connection via the connecting bores 38 to the passage 35 is prevented from being larger parts may get into the pump working space, in the case where there is a breakage of parts of the pressure valve. In a simple way, the opening pressure of the check valve by interposing shims on the spring plate 37 can be adjusted.

p0014The embodiment of Figure 3 is in turn a development or variation to the embodiment of Figure 2 or Figure 1. Notwithstanding the above embodiments, a flat seat valve closure member is running in a conical seat valve closing member 19 'is provided, its counterpart, the planar face 41 of the tubular valve body 12' is. Moreover, the valve has the same structure as that shown in FIG 2. The there in the valve closing member provided longitudinal bore 26 is here held as a recess 26 'only briefly. On it, the throttle bore connects 28th This embodiment has the advantage that the size can be kept very small in the axial direction. The machining of the sealing surfaces is simple, although 'is an exact guidance of the valve closure member 19 necessary. To this end, 19 'guide surfaces 42 are provided on the edge of the substantially hat-shaped valve closure member, cooperating with an adapted internal bore portion 43 of the recess. 8

p0015A particularly advantageous embodiment of the invention consists in the execution of the embodiment of Figure 4. Again, the tube is threaded into the housing of the fuel injection pump connecting piece 6 is provided with the axial recess 8, in the pump side of the opening, a tubular valve body 12 'is used, the an outer collar 14 via which it is clamped between pump-side end face 15 of the connecting piece and the shoulder 16 of the threaded bore. 7 Deviating from the embodiment shown in Figure 1, the valve body 12 ', however, a smooth inner bore 44 in which the valve closure member 19 is guided with its guide faces 20th Also with this valve body 12 'of the valve seat 17 is provided at the end ausnehmungsseitigen.

p0016In a particularly advantageous manner is now as an abutment for the compression spring 34 of the check valve 30, a sleeve 45 is pressed, the preferably still on injection pumps end a flanging has 46, on which the compression spring 34 can be supported safely. The flanging 46 limits the axial passage 35 'to the feed pipe 4. This configuration has the advantage that 45 of the opening pressure of the check valve 30 can be set precisely by more or less wide pressing the sleeve. This can preferably be carried out in an assembled state of the pressure valve, so that accurate setting can be achieved with minimal effort. The check valve is more stressed by the terminal-side end thereof with hydraulic fluid from a constant pressure source in the amount of the adjusted holding pressure and the sleeve 45 continuously pressed so far, until the valve closes.

p0017When the example described according to Figure 4, the throttle bore 28 is provided instead of the guide pin 25 at the opposite end of the longitudinal bore 26 '. Further, in this embodiment, the maximum stroke of the valve closing member 19 'by engagement with a hat-shaped spring plate 47 can be limited, which is constructed in the same manner as the hat-shaped spring plate 37 in the embodiment of FIG. 2

p0018Especially for the use of such a hat-shaped spring plate 47 is, in an embodiment variant according to Figure 5 the valve closing member 19 '' constructed so that the throttle bore 28 'now radially from a blind bore 26 "in the region of a guide pin 48 on the connecting bore-side end face of the valve closing member 19' ' branches. Moreover also includes the embodiment of figure 5 includes a valve body 12 "on, in its continuous inner bore 44 on injection pumps end a sleeve 45 'is pressed, which serves as an abutment for the compression spring 34 of the check valve 30.

p0019This valve such as that operates substantially the same as according to figure 4 and has the advantage that in cases where the valve closing member 19 'comes to bear against the hat-shaped spring plate 47, the throttle bore is not damaged or clogged with dirt particles.

p0020With the advantages of a shorter length, the embodiment of Figure 6, in a modification to the embodiment of Figure 4 is a flat seat valve closing member 19 '' 'to. This has a substantially hat-like shape, the end face 49 forms a sealing surface. The valve closure member cooperates with a substantially disc-shaped valve body 14 '' 'together, the axial longitudinal bore 44', into which a sleeve 45 of the same type as the sleeve 45 is press-fitted to the Figure 4 embodiment. This sleeve also serves as an abutment for the compression spring 34 of the check valve 30 with a longitudinal bore 26 in the valve closing member 19 'on the valve closing member 31' co-operates. The in the valve closing member 19 'adjacent end face 50 of the valve body 12' '' is ground flat and serves as the seat for the valve closing member 19 '.

p0021In the last example shown Figure 7, the pressure valve is constructed in a similar manner as in the above embodiments. The connecting piece 6 is also here has the recess 8, removes from which the connection bore 10th In the recess projects into a tubular portion of the valve body 52, a valve seat 53 has at its projecting into the Ausneh mung end face which cooperates with a corresponding conical sealing surface 54 of a valve closure member 55 of the pressure valve. This valve closure member 55 is substantially the same construction as the valve closing member 19 'of the embodiment of Figure 4, and has a guide pin 56 which projects into a through hole 57 of the valve body 52 and there lying in two parallel radial planes guide surfaces 58 having the formed like wings are and allows the passage of fuel from the pump end of the through hole 57 to the valve seat 53rd The valve closing member 55 is biased by a compression spring 23rd

p0022The pump-side end of the through hole 57 is connected by means of a longitudinal bore 64 in the valve closing member 55 with the connecting bore-side part of the recess 8, wherein the throttling point 65 is provided at the pump end of the guide pin 56 in the longitudinal bore 64th This pump-side end 63 of the guide pin is designed as a sealing surface which cooperates with a planar end face 62 of a disc-shaped valve closure member 59th This closing member 59 of the check valve 60 has, at its radial periphery to guide wings 66, through which the valve closure member 59 is guided in the through hole 57th The back of the valve-closing member is loaded by a compression spring 67 which is supported in an annular recess 68 of an intermediate plate 69, which is connected downstream of the valve body. The valve body has, as in the preceding embodiments, an outer collar 70, on the front side 15 of the connecting piece 6 comes to rest, the threaded bore the valve body together with the intermediate plate on the shoulder 16 of the Ge 7 holds. From the annular recess result from a plurality of holes 70, which connects the annular recess 68 with the subsequent delivery line. 4 A core 71 around which the annular recess 68 extends, serves as an axial stop for the valve closing member 59th

p0023This embodiment has, as the embodiments according to Figures 1, 2 and 3 has the advantage that the adjustment of the opening pressure of the check valve 60 can be easily manufactured by placing intermediate discs, advantageously by means of the intermediate plate 69 is provided for mounting such intermediate rings easy accessibility. Furthermore advantageously, the valve closure member 59 at a very low mass and may be in the plane in which the joint sealing surfaces of the pressure valve closing member 55 on the one hand and the closing element of the check valve are on the other hand, easily adapt. With the low mass it is ensured that on reaching the state pressure, a precise and rapid closing of the check valve 60 takes place without the latter according to a first contact bounce back t. By providing a plurality of through holes 70 in the intermediate plate 69 of the individual cross-section is kept very low at a major Gesamtdurchflußquerschnitt, so that here a protective effect is obtained against the ingress of metallic debris in the pump working space, if parts of the pressure relief valve should fail.