Combustion Engine and Injector for a Combustion Engine

The invention relates to a combustion engine, comprising a number of combustion cylinders each provided with at least one first atomizer injecting fuel in said cylinder and one injector having at least one first fuel pump for delivering fuel to each first atomizer, wherein the fuel chamber of each first fuel pump has a pump volume adjustable with control means, said pump chamber communicating through an inlet valve with a fuel supply and through a fuel outlet with a first atomizer and being limited by at least one displacer body having a stroke adjustable by means of control means.

The invention has for its object to improve the ignition of the fuel-air-mixture provided in the combustion cylinder at a low fuel expenditure. To this end and in accordance with the invention the displacer body of the first fuel pump is coupled with at least one armature of at least one electro-magnet and at the same time at least one air supply conduit of the combustion engine is provided with a second atomizer supplying fuel to the air.

In this combustion engine the first atomizer may inject fuel in a finely divided condition in the vicinity of the spark-plug, so that the extra rich fuel-air-mixture can be ignited easily in the vicinity of the spark-plug as a result of which the combustion of the remaining, relatively poor fuel-air-mixture takes place.

Preferably each combustion cylinder is provided with said first atomizer injecting fuel therein as well as with a second atomizer injecting fuel at the outside thereof. Then the division of the fuel along each combustion cylinder is better controlled.

The invention also provides an injector for delivering fuel to a combustion engine, wherein the pump chamber of at least one fuel pump having a volume adjustable with control means communicates through an inlet valve with a fuel supply, is limited by at least one displacer body and has a fuel outlet for connection to a first atomizer injecting fuel into a combustion cylinder. Said injector is improved in accordance with the invention in that the displacer body is coupled with the armature of an electro-magnet and the injector at least comprises a second fuel pump having a fuel outlet for connection to a second atomizer injecting fuel outside of said combustion cylinder.

Preferably each first fuel pump has a smaller pump volume than each second fuel pump.

Then the first fuel pump may easily inject fuel at a considerably higher pressure than the second fuel pump.

A simple injector is obtained when one pair of electro-magnets energizes the armature of at least one first fuel pump and the armature of at least one second fuel pump.

In order to make the stroke of the armature of the first fuel pump smaller than the stroke of the armature of the second fuel pump, said armatures are preferably separated from each other.

The aforesaid and further features of the invention will be set out hereinafter with reference to a drawing.

In the drawing

FIG. 1 is a plan view partly broken away of a preferred embodiment of an injector according to the invention, showing schematically the connection with a combustion engine,

FIG. 2 is a sectional view taken on the line II-II in FIG. 1,

FIG. 3 is a sectional view on an enlarged scale taken through a detail III in FIG. 1,

FIG. 4 is a sectional view taken on the line IV--IV in FIG. 1, and

FIG. 5 is a diagram of an electronic circuitry for the energization of electro-magnets.

Two pairs of electro-magnets 2a and 2c, 2b and 2d respectively are rigidly secured by means of bolts 6 to a mounting plate 1 forming the frame of the injector 66. Each of the electro-magnets 2a, 2b, 2c and 2d comprises a core 10 formed by a stack of magnet plates 23 and an energizing coil 14 surrounding said core 10. The bolts 6 engage the magnet plates 23. Each electro-magnet 2a, 2b, 2c and 2d is embedded in a block of synthetic resin 36. Two sheet-like armatures 18h and 18n are pivotally arranged between each pair of alternately energized electro-magnets 2a, 2c and 2b, 2d respectively (see FIG. 4). Each armature 18h and 18n is pivoted by one rectangular end 4 to a bearing 37 of wear-tight, relatively hard, elastic material, e.g. rilsan or arnite, said bearing 37 being embedded in a metal bearing block 105 mounted by means of screws 106 to the mounting plate 1. Each end 4 is provided with a space f of 0.05 mm in a slot 24 of the bearing 37, so that when energizing an electro-magnet 2a, 2b, 2c or 2d the respective armatures 18h and 18n move at the same time first along the remaining space f to the electro-magnets energized, then the armatures 18h and 18n press the elastic material of the bearing 37 somewhat and if necessary the armatures 18h and 18n pivot at last about their end 4 which lies against a side of the slot.

The ends 4 of the armatures 18h and 18n are shut up in a vertical direction, in that the bearing 37 is locked up by a conical upper end 38 in the bearing block 105, in that a pin 43 embodied in the armature 18h abutts against the upper side of the armature 18n and in that a screw 106 screwed into the mounting plate 1 is screwed against the lower side of the armature 18n.

At its free end 5 each armature 18h holds a coupling member 20, with which are connected two displacer bodies 22 of two first fuel pumps 32ah and 32ch, 32bh and 32dh respectively. Each armature 18n holds at its free end 5 a coupling member 20 with which are connected two displacer bodies 22 of two second fuel pumps 32an and 32cn, 32bn and 32dn respectively. The stroke of the displacer bodies 22 is determined by adjustable controlmeans arranged on each side of the coupling members 20 formed by two wedges 26 and 33.

Each of said fuel pumps comprises a pump housing 42 having a pump chamber 29 bounded by an inlet valve 39 and an outlet valve 41, a fuel inlet 27 to be connected with a fuel tank 51 through a fuel supply pump 40 and a fuel outlet duct 28. The pump housings 42 of the fuel pumps 32bh, 32bn, 32ch and 32cn constitute together a stiff and compact housing block 107 as well as the pump housings 42 of the fuel pumps 32ah, 32an, 32dh and 32dn do so. The pump housings 42 are arranged pairwise coaxially opposite one another and at a distance h from each other by means of connecting means. These connecting means are formed by fitting pins 61 and bolts 62, which rigidly secure the housing blocks 107 with the base plate 1. Annular grooves 83 are arranged in the lower side of the housing blocks 107, while rubber O-rings 82 are provided in said grooves 83 for sealing the housing blocks 107 with respect to the base plate 1. The front surfaces 60 of the pump housings 42 are held in accurate parallel positions to one another by the fitting pins 61.

The displacer bodies 22 are each made of a synethetic resin, preferably a superpolyamide, and comprise each a cup-shaped piston 63 and a shaft 65 which is attached with the insertion of glue into a hard-steel coupling member 20 comprising a guide collar 64 engaging the pump chamber 29.

FIG. 1 illustrates an engine operating with a firing order of 1-3-4-2. The first fuel pumps 32ah, 32bh, 32ch and 32dh are connected to the respective injectors 30bh, 30dh, 30ah and 30ch which provide direct injection into the cylinders. The injection timing is at about 50.degree.-30.degree. before top dead center during the compression strokes of the cylinders, with ignition timing in the range 30.degree.-20.degree. BTDC. The injection volumes vary within the range of 1-5mm.sup.3 and the injection is at a pressure of about 35 atmospheres. The second pumps 32an, 32 bn, 32cn and 32dn are connected to the intake manifold injectors 30an, 30cn, 30bn and 30dn respectively. Thus, as #1 cylinder is receiving direct injection during the latter part of its compression stroke, cylinder #4 is receiving indirect injection into its intake manifold branch 50 during the latter part of its exhaust stroke, and so on for other similarly paired cylinders in the firing sequence. Thus, each pump pair such as 32ah, 32an provides direct injection to one cylinder at about 50.degree.-30.degree. before top dead center for that cylinder while providing indirect injection to another cylinder at about 50.degree.-30.degree. before bottom dead center for that cylinder, during the respective compression and exhaust strokes of the cylinders involved. The second injectors operate at low pressure, i.e., 5 atmospheres, and inject relatively large quantities of fuel ranging, for example, from 6-40 mm.sup.3 per stroke. For engines having a crankshaft configuration requiring the firing order 1-4-3-2, the pumps will require different connections. For example, the pumps 32ah, 32bh, 32ch and 32dh would be connected to the injectors 30dh, 30bh, 30ah and 30ch while the pumps 32an, 32bn, 32ch and 32dn would be connected to the injectors 30cn, 30an, 30bn and 30dn. A second fuel pump for low pressure is provided beneath each first fuel pump for high pressure. This will be clarified in FIG. 2 with reference to the fuel pumps 32ch and 32cn. The fuel pump 32ch has a particularly small pump volume. In order to control the output yet accurately a particularly small diameter of the pump cylinder 110 is used so that for obtaining an output of e.g. 1 m.sup.3 with a diameter of 2 mms the stroke amounts about 0.3 mms. As the conduction of the displacer body 22 can be hardly realised with a small diameter the displacer body 22 is guided through a guide collar 64 into a cylindrical room 108 having a larger diameter of for instance 6 mms, said guide collar 64 being provided with an axial groove 109 for the escape of air. The fuel pump 32cn comprises a pump cylinder 59 having a larger diameter of for instance 6 mms, in which cylinder also a guide collar 64 is guided. The outer diameter of the pump cylinder 59 is smaller than the diameter of the fuel inlet 27, through which the pump cylinder 59 transversely extends. The valve housing 111 of the fuel pump 32ch is provided above the pump cylinder 59 of the fuel pump 32cn, said valve housing 111 comprising the inlet valve 39 and the outlet valve 41 with their accompanying parts which are represented in an exploded view. Behind the aforesaid parts and at a somewhat lower level the valve housing 111 of the fuel pump 32cn is provided having to this end an extra long pump cylinder 59.

The displacer bodies 22 of each pair of fuel pumps 32ah and 32ch; 32bh and 32dh; 32an and 32cn; and 32bn and 32dn respectively are coupled with one another by means of a coupling member 20. Each coupling member 20 is coupled with the respective armature 18h or 18n through an elastic ring 67 gripping around a pin 68 of an armature 18h or 18n.

The displacer volume of each fuel pump 32ah and 32ch; 32bh and 32dh; 32an and 32cn and 32bn and 32dn respectively is determined by the stroke of a coupling member 20 which is adapted to reciprocate by convex stop surfaces 49 of a stop member 79 between the wedges 26 and 33. In order to maintain the accurate adjustment of said stroke the stop member 79 as well as the wedges 26 and 33 are made of hard steel, whilst said wedges bear on hard steel cylinders 59 and 110 pressed into the pump housing 42. At each stroke the coupling member 20 abuts against a hard stop, whereas the mass of the armatures 18h and 18n moves on over a small distance and is resiliently stopped by the ring 67.

Between the two housing blocks 107 wedges 26 and 33 are disposed to serve as common control means for each of said eight fuel pumps. The distance t between the coupling members 20 is small so that fluctuations of the pump yield due to mounting errors are small.

Each atomizer 30ah, 30bh, 30ch, 30dh, 30an, 30bn, 30cn and 30dn comprises a needle 7, a conical end 21 of which is tightly drawn by a strong spring 8 to the seat 9. At a high pressure of fuel in a chamber 11 communicating with the fuel duct 28 and a chamber 19 communicating with the former through a perforated collar 12 said end 21 is urged away from the seat 9 against the action of the spring 8 (see FIG. 3).

Each electro-magnet 2a, 2b, 2c and 2d is controlled by a circuitry 17 shown schematically in FIG. 5. The transistors TR.sub.1 and TR.sub.2 in conjunction with the associated resistors R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 and the capacitor C constitute a monostable multivibrator. The resistor R.sub.1 and the capacitor C determine the time constant. The collector output of the transistor TR.sub.2 forms via the resistor R.sub.4 the input of the transistor TR.sub.3, which serves as an amplifier for the current to be passed through the coil L.sub.1 of the electro-magnet 2a, 2b, 2c or 2d. Across the coil L.sub.1 is connected a quenching diode D.sub.1. To the input terminals K.sub.1 and K.sub.2 is connected a supply source 35 and the input K.sub.3 serves for the application of a control-pulse originating from a pulse generator 34. The pulse generator 34 may be coupled, for example, with a cam shaft 13 of the combustion engine 31 and comprises a rotatable permanent magnet 15, which passes alternately by one of the four coils 16a, 16b, 16c and 16d for sequentially energizing the electro-magnets 2a, 2b, 2c and 2d respectively. Each of said four coils 16a, 16b, 16c and 16d is disposed between the input terminals K.sub.3 and K.sub.1 of an associated circuit 17. In this way the atomizers inject the fuel required for each combustion cylinder during each cycle of the combustion engine 31 at the required instants. The order of succession of energization of the electro-magnets 2a, 2b, 2c and 2d is chosen so that each of the wedges 26 and 33 is just released from a coupling member 20 in each cycle so that each of them can be adjusted individually by a slight adjusting force.

FIG. 1 shows a cylinder 73 having a piston 80 for driving the wedge 26. A measuring chamber 85 of the cylinder 73 communicates constantly via a duct 86 with the air inlet manifold 72 of the combustion engine 31 connected via a throttle valve 91 with an air filter 58.

A reset spring 74 centrally engages the piston 80 through a cup spring 75 and a ball 76. The wedge 33 is displaced, independently of the wedge 26, under the action of other factors, for example, atmospheric pressure by means of a control-member 77. The piston 80 is coupled by means of a leaf spring 52 with the wedge 26.

The cylinder 73 has fastened to it an electric switch 92, which is actuated by way of a bar 93 by the cup spring 75 of the piston 80, when the pressure in the inlet manifold 72 drops below a given pressure of, for example, 200 mms Hg absolute value. The tension of the spring 74 and the switching position of the piston 80, shown by broken lines in FIG. 1, are chosen accordingly. The given pressure is comprised between the values of about 250 and 150 mms Hg produced in the inlet manifold 72 in an idle run (stationary run). In the switching position of the piston 80 the wedge 26 is in the minimum state, in which the fuel pumps 32ah, 32bh, 32ch, 33dh, 32an, 32bn, 32cn and 32dn yield the minimum quantity of fuel required for perfect combustion. Upon deceleration the pressure in the inlet manifold 72 drops below said given value. Then the quantity of air entering the combustion cylinders 3a, 3b, 3c and 3d is too small for ensuring perfect combustion. As soon as after deceleration a sufficient quantity of air is available in the inlet manifold 72 for ensuring satisfactory combustion, the required minimum quantity is given off. In this situation the combustion engine 31 supplies only little power and thus gradually gains in force, which is to be preferred over an abrupt start. The switch 92 is connected between the accumulator 35 and the terminal K.sub.1, so that, when the switch 92 is open, no control-pulses are supplied.

As is illustrated in FIG. 5 each first atomizer 30ah, 30bh, 30ch and 30dh injects directly into a cylinder 3a, 3b, 3c and 3d respectively and preferably in such a direction and at such an instant of the engine cycle that at the instant of ignition the spark gap 98 of a spark plug 95 is surrounded by a cloud 97 of finely atomized fuel, whereas at areas remote from the spark gap 98 the mixture has a poor fuel content. This heterogeneous distribution of fuel in the combustion cylinder is highly conducive to ignition. Owing to the use of the electro-magnetic drive of the displacer body 22 the fuel can be finely atomized at a pressure of 35 ato, about 10 ato, for example, serving to overcome the compression pressure and the remainder for carrying out the fine atomization. The force exerted on the armature 18h by an electro-magnet 2a, 2b, 2c or 2d strongly increases according as the armature 18h approaches this energized magnet. Thus the armature 18h and hence the displacer body 22 of the fuel pump 32ah, 32bh, 32ch, 32dh respectively is accelerated even at the end of the pump stroke so that even with an opened atomizer 30 the fuel to be atomized maintains a great pressure difference across the atomizer opening, which ensures a fine atomization. Therefore, an atomizing pressure of 20 ato at a compression pressure of 12 ato is amply sufficient. The magnetic force exerted on each armature 18h can be enhanced by taking care of the fact that each armature 18h is provided as close as possible at the electro-magnets. To this end the thickness S.sub.h of the armature 18h is greater than the thickness S.sub.n of the armature 18n, said last armature 18n requires owing to a somewhat larger pump stroke a larger free swing space.

By applying the electro-magnetic drive the instant of injection can be readily changed for matching the conditions varying in the course of operation or for matching a particular combustion engine 31.

The identical change of the instant of injection with respect to the instant of sparking of all combustion cylinders 3a, 3b, 3c and 3d is carried out by means of a speed-, torque- and/or temperature-sensitive regulator 99, which shifts an annular support 100 of the coils 16a, 16b,16c and 16d in the direction of arrows 101 (see FIG. 5).

The support 100 holds, in addition, a set of coils 102a, 102b, 102c and 102d connected each by contacts 103a, 103b, 103c and 103d respectively of a switch 103 between the inputs K.sub.1 and K.sub.3. The switch 103 is switched on at a low number of revolutions of the combustion engine 31 by a control-member 104, which may be the starting knob of the combustion engine 31 and which actuates simultaneously a switch 81 for switching on the electric starting motor 96. In this way during the start every electro-magnet 2 is energized twice and afterwards only once per engine cycle. During the start twice the maximum yield of each fuel pump is provided.

Various modifications of the above described and illustrated embodiment are possible. It is imaginable, for example, that the first fuel pumps 32ah, 32bh, 32ch and 32dh are supplied with another fuel which can be more easily ignited than the second fuel pumps 32an, 32bn, 32cn and 32dn. Then the first fuel pumps are of course connected to a fuel supply which is separated from the fuel supply of the second fuel pumps.