Fuel injection pump

PATENT DESCRIPTION,

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OFFICE

PATENT

PRL

Additional patent to patent no. - Patent pending: 79 11 26 (P. 219888)

Priority: 78 11 25 Great Britain

The application was announced: 80 08 11

Patent description published: 1986 02 10

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Int. Cl⁸ F02M 41/14

The inventor: -^-'

Patent Holder: Lucas Industries Limited, Birmingham (United Kingdom)

Injection fuel pump and

The present invention relates to an injection fuel pump for injecting liquid fuel into an internal combustion engine.

Injection fuel pumps are known for injecting fuel into an internal combustion engine having a body, a rotary distributor mounted inside the body, wherein the distributor, during operation, is driven in a manner ensuring time dependence on the rotation of the engine with which the pump is connected, a transverse hole located in the distributor, a piston located in the opening in the manifold, a cam pusher located outside the piston and cooperating with the cam surface of the cam ring surrounding the distributor, a stop assembly for limiting the outwardly directed movement of the piston and a set of channels * for transferring fuel to and from the orifice as the distributor rotates. This type of fuel pump is required to change the amount of fuel fed to regulate the amount of fuel delivered to the engine connected to it. This is achieved by using a throttle through which the fuel flows under pressure to the hole from the fuel source, whereby the amount of fuel flowing into the hole for a given throttle setting varies according to the change in engine speed. Odd engine speed increases the amount of fuel delivered to the engine each time the piston «

moves in, shrinks. Odd engine speed decreases, the amount of fuel delivered to the engine when the piston moves⁵ in, the stop assembly increases and operates, limiting the maximum amount of fuel that can be delivered. To ensure that the amount of fuel fed is kept constant each time the piston moves inwards¹⁰ the throttle must be set every time the engine speed changes or the pressure of the fuel flow in the throttle changes. For this reason, it is difficult to provide a pump control that, when set in a certain position, ensures that a predetermined amount of fuel is supplied to the engine regardless of its speed of rotation.

Another way to achieve a change in the amount of fuel delivered to the engine is to measure the volume of fuel in a variable-volume chamber located in the body, and then send the measured amount of fuel to the manifold hole. After₇the measures are made by means of a slide, the stroke of which in the chamber is set directly by means of an adjustable bumper, theoretically such a solution ensures a change in the amount of fuel fed when the piston is moved inwards according to the bumper setting. This pump design does not solve the problems of protrusion³⁰ fuel supplying from the chamber to

128 252

128 252 bore and in practice it was found that for a given position of adjustable bumper there are significant changes in the amount of fuel fed when the engine speed changes.

A method of regulating the amount of fuel fed is also known, while the piston is moved inwards by positioning the stop assembly, so that the piston works as described above, with the piston not practically having the problem of feeding the fuel into the hole. A fuel pump that works based on this method of regulation is known from United Kingdom Patent No. 1,171,226. This pump has a fork having an inclined surface cooperating with the corresponding surface on the pusher. The fork is connected to or forms part of a sleeve mounted so as to allow axial movement on the drive shaft, which rotates with the distributor. The disadvantage of the pump is that the sleeve rotates together with the shaft, and to ensure that it can be adjusted, the sleeve is connected to an adjustable part attached to the pump body. Any slip between the bushing and this part can upset the pump, and the friction between the bushing and drive shaft increases the force necessary for the bushing to move.

The object of the invention is to construct an injection fuel pump which does not have the disadvantages of the known pumps with a simple design and convenient to use. '

The object of the invention is achieved by constructing an injection fuel pump for injecting fuel into an internal combustion engine, which has an assembly for changing the axial location of the distributor in the body, the distributor being rotatably mounted in the pump body, and during the axial movement of the distributor a section by which a plunger is located in a transverse hole in the manifold, it moves outwards and changes when fuel is fed into the hole. The projections for limiting the outward movement of the piston are complementary inclined surfaces on the pusher and a part with an enlarged diameter, the part with the enlarged diameter mounted on or being part of the drive shaft.

The assembly for changing the axial position of the distributor comprises a spring for orienting the distributor in one axial direction relative to the body portion and a lever adapted to cooperate with the end surface of the distributor to move the distributor against the spring direction.

The pump has springs to direct the distributor in one axial direction relative to the body part, the surface of the distributor or on the drive shaft, operatively connected to it, and a control pressure valve which acts on this surface counteracting the force generated by the spring. One of the springs acts indirectly on the drive shaft and distributor and the surface on the distributor is defined by the distributor end distant from the drive shaft.

The drive shaft has an enlarged diameter part surrounding the distributor part in which a transverse hole is located, the enlarged diameter part having an opening connected to the piston in which the pusher is located.

The driving shaft has an enlarged part and diameter surrounding the part of the distributor in which the transverse hole is located, wherein the part with the enlarged diameter has an opening connected to the piston in which the pusher and the pin connecting the piston with the pusher are located, the movement rotary is transferred from the larger diameter part to the distributor by means of a pusher, a pin and a piston.

The cam pusher has a roller and guide supporting the roller, the raised surfaces being defined on the lateral surfaces of the guide projections and the internal surfaces of the enlarged diameter of the drive shaft.

The drive shaft has a deepened hole in which the piston is slidably mounted, cooperating with the adjacent end of the distributor and a set of channels through which the regulating pressure is supplied to the deepened hole acting on the piston.

The pump has a thrust thrust bearing plate located between the spring and the distributor.

The subject of the invention is shown in the embodiment in the drawing in which Figure 1 shows an axial cross-sectional view of the fuel injection pump; Figure 2 is a section of the pump in section along another plane; figures 3 and 4 show the cross-sectional elements of the pump shown in figure 2; Fig. 5 is a cross-sectional view of the components of the pump of Fig. 1; Fig. 6 is a cross-sectional view of a portion of the pump in a second embodiment; FIG. 7 - a fragment of the pump in another embodiment in axial section; Figure 8 is a side view of a portion of the pump in another embodiment; Fig. 9 is a sectional view of the pump fragment as in Figs. 3 and 4, in another position, in another embodiment; Fig. 10Om - a fragment of the pump as in Fig. 1, in another embodiment, in axial section; Fig. 11 and Fig. 12 - Fragment of the pump in view towards lines A-A and B-B on. Fig. 10; figure 13 is a perspective view of the pump element shown in figure 10.

The fuel injection pump has a body 10 formed from a cup-shaped element 11, whose open side is closed by a cover 12. The body 10 has headers 13 with holes through which the pump is attached to the engine (Fig. 1).

In the cup element 11 there is mounted a rotary drive shaft 14 which during operation is coupled to the motor drive element so that it rotates synchronously with the motor. The drive shaft 14 is located in a cylindrical chamber 15 defined by both body elements · 10 and has a part 14a with increased diameter located inside the chamber 15. Part 14a has two diametrically arranged holes 16. The portion 14a of the drive shaft 14 is hollow, and at its end remote from the reduced diameter portion of the shaft, the inner surface is cylindrical. Finally, the part 17 of the pin defined by the cover 12 enters. The remaining part

128 252 the inner surface of the drive shaft, with an increased diameter, narrows. The drive shaft 14 has a cylindrical counterbore 18 on the opposite side. An oil seal 19 is arranged on the outside of the body 10, cooperating with the drive shaft 14 and a slide bearing 20 rotatably supporting the shaft, the shaft being additionally supported on part 17. The shaft is mounted axially by means of abutment surfaces in contact with the end surfaces of the shaft parts with increased diameter. In one case, the abutment surface is defined directly by the cover 12, and in the other the abutment surface is a plate 21 applied to the shaft, which is the cover of the pump 22 supplying fuel at low pressure. The pump rotor 22a is located on the drive shaft 14 and has blades cooperating with an off-axis surface in a stationary ring 22b which is located in the cup element 11 of the body 10. The low pressure pump 22 has a fuel inlet 23 connected to the fuel inlet 23a and a fuel outlet 24 and relief valve 25, to maintain output pressure within the required limits, connected between inlet 23 and outlet 24.

In the cup element 12 there is a cylindrical opening 26, in which the sleeve 27 is located. In the sleeve 27, a distributor 28 is arranged in a manner enabling rotation and axial displacement of the distributor 28, the head of which has an increased diameter protrudes into the chamber 15. Inside the distributor head there is a lateral opening 29, in which two pumping pistons 30 are located. The opening 29 connects to the blind passage channel 31 located in the distributor, the end of which is located in the head part and is pinned. Channel 31 is connected by means of single or multiple connecting channels to two diametrically spaced ria of the distributor outer surface with longitudinal slots 32. Channel 31 'is also connected to the longitudinal slit 33 located on the outer surface of the distributor and connected to a plurality of outlet windows 34 located in the sleeve 27. The outlet windows 34 connect to respective outlets 35 located in the cup element 12 of the body 10, with each outlet 35 having a typical discharge valve 36.

The slots 32 connect to the inlet windows 27 in the sleeve 27 connected to a circumferential groove 38 located on the outer surface of the sleeve 27. The groove 38 is connected to the outlet 24 of the low pressure pump 22 by means of a two-position valve 39 controlled by an electromagnetic assembly 40. When required the gap 32 is provided with outlet windows equal to the number of inlets.

Around the distributor head 28 there is a cam ring 41 on whose inner surface there are diametrically two cam projections. In individual embodiments, when the pump powers the six-cylinder engine, ring 41 has three pairs of projections. The cam ring 41 is then rotated around the axis of rotation of the distributor by a hydraulic assembly 42 connected to the cam ring by means of a radially positioned pin 43. The hydraulic assembly 42 has a spring loaded piston located inside the cylinder. Fluid is supplied to one end of the cylinder under pressure, which acts on the piston in the opposite direction to the elastic load.

A pair of pushers are located outside the pistons, each of which has a roller 44 positioned in the guide 45. The pushers are axially positioned with respect to the distributor by a pair of side plates 46, 47 attached to the side walls t of the distributor head. The side plates 46, 47 are ring-shaped and have outwardly projecting protrusions 48 that enter into holes 16 located in a portion of the drive shaft with increased diameter (Fig. 5). Plates 46, 47 transfer rotational motion from the drive shaft to the distributor. The guides 45 are also located in the holes 16 and the rotary movement is transmitted by the guide directly from the drive shaft. The lateral peripheral surfaces of the guides have circumferentially protruding projections 49 whose outer radii. the surfaces are inclined so as to allow cooperation with the inclined surfaces inside the part with increased diameter of the drive / shaft.

During operation, when fuel is supplied to the hole 29 through the groove 32 and the inlet channel 37, the pistons 30 are moved by the fuel pressure outward, transferring this movement to the rail 45 and the rollers 44. The outward movement is limited by the resistance of the inclined surfaces of the guides and the drive shaft. The amount of this movement varies by shifting the distributor axially, which makes it possible to regulate the amount of fuel supplied to the hole 29 and determines the amount of fuel flowing through the outlet as the pistons 36 are moved inward through a pair of cam projections.

The axial location of the distributor changes mechanically or hydraulically. In the described embodiment, the position of the distributor is changed by changing the pressure in the chamber 50 located at the end of the opening 26 in the cup element 12 of the body. The end of the opening 26 is closed with a plug and the pressurized fuel is fed into the chamber 50 through a nozzle 51 located in the sleeve 7. The nozzle 51 is connected to the outlet 24 of the pump 22. Fuel can leak from the chamber 50, and the pressure in the chamber is controlled by the solenoid valve 52. The distributor is pressed by a cylindrical pressure spring 53 located in the blind hole 18 in the drive shaft 14. The spring 53 interacts between the shaft and the distributor by pressing the distributor in the opposite direction effect of fuel pressure in the chamber 50. χ

By changing the pressure in the valve 52 by means of the valve 52, the axial position of the distributor changes, and thus the amount of fuel supplied to each. when the pistons are moved inwards.

For a given axial position of the distributor and negligible leakage, the amount of fuel supplied by the pistons will remain unchanged for the whole

128 252 engine speed range. The axial position of the distributor is determined by a position transducer 54 located in the hole plug 26 in a scalable manner. Part of the transducer is located in the divider. The signal sent by the transducer is used to determine the rotational speed of the distributor and its axial position, which in total allows determining the amount of fuel supplied by the pump. During operation, these signals are fed to the electronic control system, where additional signals are provided that show various engine parameters and the required engine speed, with the control system controlling the operation of the valve 52 ensuring delivery of the right amount of fuel to the engine.

Alternatively, the axial position of the distributor is set by means of a mechanical assembly comprising a pusher 28a cooperating with the opposite opposite spring 53 and the end of the distributor. The pusher 28a cooperates with the lever 28b (Fig. 6).

In both cases, the force necessary to move the distributor is greater than the force caused by the spring 53, because given the relative rotation of the distributor 28 and sleeve 27, the friction between them is minimal.

When the pressure in the chamber 50 should drop for a specific reason, the distributor 28 is moved by the spring 53 to the position where the maximum amount of fuel will be fed by the pump, which may cause damage to the engine. To counteract this, a spring 6l located at the opposite end of the distributor was used, which sets the distributor in the minimum fuel supply position (Fig. 7). One end of the spring 61 cooperates with an adjuster 62, by means of which the force generated by the spring is regulated, and the other end of the spring is connected to the thrust bearing thrust plate 63, which is directed against the distributor. Thrust plate thrust bearing 63 is made of hand-woven material of synthetic resin or metal and separated down the manifold by a film of fuel supplied from the channel 64 connected by means of a throttle to the outlet of the low pressure pump.

The opposite end of the distributor is connected to a piston 65 located in a cylinder formed in the propeller shaft 14. Fuel under pressure is supplied to the piston from the low pressure pump outlet by means of a throttle and regulated by a valve similar to valve 52. In this system, the pressure applied to the piston must be increased to increase the amount of fuel fed to the engine. Preferably, the supply of fuel under pressure to the cylinder containing the piston takes place via a channel in the distributor, which opens to the periphery of the distributor and connects to the circumferential groove 66 located between the adjacent ends of the two sleeves forming the bearing sleeve 20, whereby excessive wear of the sleeve occurs and there is a fuel leakage, the pressure applied to the piston will decrease, reducing the amount of fuel delivered to the engine. The disadvantage is that the piston could jam, at

In practice, the drive shaft is subject to torsional vibrations and a change in speed, which causes relative movement of the piston and shaft.

Fig. 8 shows the modified .5b of the distributor drive and the positioning of the rollers and guides relative to the distributor. The outer ends of the pistons 30 are pre-drilled and into these holes insert pins 60, protruding inwards from the pushers, having a graduated diameter. The ends of the larger diameter pins enter the piston holes, while the smaller diameter pass through the holes in the guides 45 and enter the circumferential grooves formed in the rollers 44. The guides 45 contact sideways with the holes 16, as in the original version, and the rotational movement is transmitted to the distributor by means of pins 60 and pistons 30, the pins axially positioning the tappets and rollers. Connected to the channel 31, radially located in the distributor, is the channel 61 usually covered by the sleeve 27 except when the distributor is set to zero capacity, i.e. shifted maximally to the left to the position where the rollers do not contact the cam protrusions. When they are in contact, the lugs have a special shape to regulate the fuel dose limitation for power horses. Any movement inwards causing the displacement of fuel from the hole in which the pistons are located will cause the fuel to flow out through the channel 61 into the chamber 15 and not into the engine.

This channel can be used for venting the pump after assembly during production, repair or in many cases when air enters the various pump channels. If desired, the channels connecting the groove 32 to the channel 31 extend to the channel * 31 in close proximity to the opening 29. In this case, low-pressure fuel will be fed into channel 31 tangentially to opening 29 and all mixed air bubbles will pass along channel 31 through channel 61.

It is beneficial to ensure venting of the pump when the distributor is set to supply excess fuel at engine start-up. In this case, the sleeve 27 has a large number of channels 62 arranged at an angle depending on the position of the outlet windows 34 (Fig. 9). The channels 62 have a certain size and are arranged so axially that when the distributor is set to excess fuel they connect with the longitudinal slots 33.

The inner ends of the channels 62 connect to the longitudinal channel 31 and therefore during the centripetal movement of the pistons a certain amount of fuel will flow through one of the channels 62, normally fuel being supplied to the respective outlets. If there is air inside the ducts, the fuel pressure generated during the centripetal movement of the pistons is not enough to open the supply valves located in the outlets and the fuel and air flow through the duct 62 up to the complete distributor. When it is required to ensure zero fuel through window 34, channel 61 is necessary for zero insertion of the manifold.

In the embodiment shown on

128 Fig. 1 and Fig. 8 a part of the drive shaft which the separator and in which the holes 16 are located has a reduced internal surface, which makes the surface difficult. To facilitate the production of the propeller shaft, the construction shown in FIGS. 10-13 is used. Part 63 of the propeller shaft has a cylindrical inner surface and two (diametrical holes 64, each of which has a pair of stop assemblies formed by the "U" arms of part 65. The U-shaped arms are part of the thin sheet metal pistons (Fig. 13), with the two arms connected internally by a connecting part 66 which has the shape of a ring and is located opposite the base wall of the part 63. Spring 53 passes through the opening in the connecting portion 66, and the inner peripheral surface of the connecting portion 66 has three projections 67, fastening one end of the compression spring 68, having several turns.

The opposite end of the spring 68 is attached to the adjacent side plate 46. The side plates 46, 47 have handles 48 disposed between the parts 65 and the pan is rotating on the distributor. The inner edges 68 of the arms of the part 65 narrow outwardly from the connecting part 66 and cooperate with inclined surfaces that support the rollers to limit the external movement of the pistons. The spring 68 makes the connecting part 66 contact the base wall of the drive shaft part 63 and supports the operation of the spring 53. The surfaces of the narrowed edges of the arms of each part 65, like the inclined surfaces on the guides, are located in the same plane, hence the construction of inclined surfaces on the guides is facilitated because they are flat and cannot be curved to match the inner surface of the shaft portion with increased diameter.

As an alternative to using separate parts 65, the increased diameter shaft part 14 has a bucket shape and is made of a piece of cylindrical material. Initially, a diametrical gap is made, which is equivalent to the slits 16, then the poid is drawn with right angles to this gap, making another gap, with a deep hole 18 in the base wall of this gap, and its side walls correspond to the shape of the edges 68 of part 65. A portion of the shaft with an increased diameter has a diametrically arranged plate with four axially extending projections, one side of which corresponds to the side walls of the guide, while the other side walls are in a plane at right angles to the first side walls and are inclined at an angle to the axis of rotation connecting with protrusions 49 on the guides.