DE2701447A1 - FUEL AND AIR DOSING DEVICE FOR AN ENGINE - Google Patents

Description

Patents uvältt *

E. Prince - Dr. G. Hauser - G. Leiser

Ernsbergerslrasse 19

8 Munich 60

Our sign; P 2325 January 13, 1977

PLESSEY HANDEL UND INVESTMENTS AG
Gartenstrasse 2
63OO Zug, Switzerland

Fuel and air metering device for an engine

The invention relates to a fuel and air metering device for an engine.

According to the invention, a fuel and air metering device for an engine is characterized by a Air flow measuring device which measures at least a portion of the air flow for the engine and one of the measured ones Air flow proportional electrical output signal generates a control device which receives the output signal of the air flow measuring device and electrical output signals generated, which change depending on the received signals, and an injector, which depends injects fuel from the signals received from the controller.

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The inventive device can deliver optimal amounts of fuel and air for an engine among themselves cause changing conditions. Precise control is achieved by utilizing the air flow for the engine. The use of an air flow measuring device enables, in particular, a continuous check of the condition of the air intended for an engine. The data obtained from the air flow measuring device can be fed into the control device can be entered, and the controller may then inject fuel into the air accordingly steer.

Various types of injection devices can be used in the device according to the invention. Preferably the injector includes a ball valve that interrupts the flow of fuel when the injector does not vibrate. Examples of suitable injectors that can be used are shown in FIG GB patent specification 1 415 539 and in patent applications P 23 04 525.2, P 25 05 801.9, P 26 05 209.5, P 26 08 103.3, P 25 31 624 .9 and P 26 37 216.7 described.

The injection device is preferably a vibrating injection device with the aid of a piezoelectric Device is made to vibrate; however, it can also be made to vibrate with the aid of other devices.

The injected fuel should preferably be in a finely atomized form so that it can be completely absorbed by the Air can be mixed. The device according to the invention therefore preferably contains a fuel atomization device,

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which finely atomizes at least part of the injected fuel. This way you can get the right amount of fuel injected into the air under the control of the controller, and that correct amount of fuel can then be substantially completely atomized using the fuel atomization device will.

The device according to the invention can be used for various types of engines, for example two-stroke and four-stroke internal combustion engines, Diesel engines and gas turbines are applied.

Usually the output signal of the air flow measuring device is a train of electrical pulses with one of the amount of air flow through the air flow meter certain frequency. Preferably the air flow measuring device is a vortex solution flow meter with a pressure transducer or a temperature transducer. Such a Vortex shedding flow meter contains a baffle that causes the Air alternately forms eddies on its two sides. The vibrations occurring within the air flow can then be determined with the help of the pressure or temperature transducer. If desired, other types of such devices can also be used, for example as air flow measuring devices, which emit an output signal that depends on temperature changes caused by a changing air flow will. In addition, the air flow measuring device can be a fluid-controlled component, for example

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be a fluid-controlled switching element in which the air is switched between two channels.

The air flow measuring device can be arranged in the main air duct leading to the engine. In this case all air for the engine is measured. The air flow measuring device can, however, also be in a secondary flow air duct be arranged so that only part of the air for the engine is measured. In the latter In this case, the fuel is preferably injected into the main air duct, but it can, if desired, with the air mixed in the secondary flow duct, and this mixture can then be used in the main air duct with the rest for the engine certain air flow are mixed before the fuel-air mixture is introduced into the engine.

Preferably, the injector and the surface to be vibrated are in the vicinity of an intake manifold arranged for a motor. Because the fuel injector and the area near the intake manifold are disposed, the fuel need not travel a substantial length of one to the intake manifold leading air intake pipe. Sometimes it can be disadvantageous to put the fuel in the air intake pipe all at once noticeable distance from the intake manifold, as the fuel will obviously hit the walls of the intake manifold moisturizes. When the engine is driven and no more power output is required, then the The driver releases the accelerator so that the engine speed decreases and a correspondingly smaller amount of fuel is injected from the injection device. This can

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often induce suction at the intake manifold, causing gasoline to be drawn off the walls of the intake manifold in the engine at a time when this additional fuel is not needed. By a corresponding attachment of the injection device and the surface to be vibrated close to Intake manifold, this adverse effect can be substantially prevented.

The control device can be a digital computing arrangement. Also the use of an analog computing arrangement is possible. The control device preferably actuates the injection device with a predetermined pulse duration per signal.

The controller may include a one-shot device that receives pulses from the air flow meter receives and generates pulses with a corresponding predetermined pulse duration. The one-shot device can have one have a fixed multiplication or division factor so that it can generate output pulses that are in a fixed Relation to the input impulses. The duration of these pulses can be changed to suit the air / fuel ratio either is kept constant if the air temperature causes changes in the air flow, or can be changed (for example by using the engine throttle) to keep the engine on temporarily can respond to demands placed on him. The air / fuel ratio can be enriched for engine acceleration and for engine deceleration and when over-revving be diluted. The air / fuel ratio can also

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can be set for other variable engine states, for example, in the event that the temperature of a coolant for the engine changes, or that the output voltage of a battery associated with the motor drops too far. If desired, the device according to the invention can also contain an oxygen sensor which may be mounted in the exhaust duct of the engine. This oxygen sensor can provide a feedback signal from the engine exhaust to the controller, and it can cause the fuel supplied to the engine to maintain a desired optimal air / fuel ratio, for example 15: 1 with regard to the quantities is correct.

The output pulses of the monostable device can be fed to an oscillator, which causes the actuation of the injection device and the vibration of this Establishment causes. There may be different types of Oscillators and associated circuits are applied; an example of this is in patent application P 26 41 921.6 described. A shut-off device operated by means of an electromagnet can also be used.

Due to practical problems, for example a slow closing of the shut-off device of the injection » device or poor dosing accuracy with a short pulse duration, it may be necessary to use the Ratio of the injection pulses to the air flow measurement pulses at predetermined flow measurement values change and ensure a corresponding change in the pulse duration. For example, an A · »· injection pulse per intake stroke of an engine in the idling state one pulse with a duration of one millisecond

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require on the injector. At high loads, a suction stroke can have five pulses with a duration a millisecond. The control device could be set so that it has the ratio of 1: 1 changes in 1: 5 with a pulse duration increased to 5 milliseconds, provided that the flow from the injector proportionally done. If the injector flow is not proportional, then the pulse duration and not the ratio is set.

If the device according to the invention is a fuel atomization device various types of such devices may be used. For example For example, the fuel atomizing device may be a fuel vaporizing device The fuel vaporizer device can be any device that heats that part of the air duct into which the fuel is injected will. In this case, the fuel vaporizing device is preferably a heat pipe.

Heat pipes are known per se. As is well known, a heat pipe is actually a closed container, which is a vaporizable one and again contains condensable material, for example water or sodium. The heat pipe collects Heat from the exhaust part of the engine, which is the vaporizable Brings material to evaporate. The steam then travels to the cooler part of the heat pipe, which is in the present Case is mounted in or around the part of the air duct into which the fuel is introduced. That evaporated

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Material gives off its heat and condenses again. The condensed liquid then flows to the hotter part of the heat pipe for re-evaporation, for example back along a wick, which is arranged in the heat pipe and forms part of this tube. The heat given off to the air duct contributes to the evaporation of the fuel bei.V / hen the heat pipe is installed in the air duct, the fuel can be used directly against v / ground the heat pipe so that a non-atomized fuel impinges directly on the heat pipe.

As an alternative to the fuel evaporation device the fuel atomization device can also be a sonic nozzle. The sonic nozzle can be designed so that the injector injects the fuel immediately before the upstream side of the nozzle, which in all Engine states with low speed and low load is throttled. When the injected Fuel hits the scope of the implementation, then shock waves arise, which continue the fuel disassemble.

Another alternative to the fuel atomizer is a device with a surface that can be vibrated. The surface may be the surface of a plate or disk, preferably so thin that it is along its own The plane vibrates and generates nodes and antinodes. Suitable surface atomizers are available in the UK Patent applications 14 58/76 and 16 419/76 described,

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The invention will now be explained by way of example with reference to the drawing. Show it:

Fig.1 shows a first embodiment of the invention Device for fuel and air metering for an engine,

2 shows a second embodiment of the invention Contraption,

3 shows a third embodiment of the invention Device and

4 shows part of a fourth embodiment of the device according to the invention.

1 of the drawing shows a device 2 with the aid of which fuel can be metered in accordance with the air present in an air duct leading to an engine 6. The device 2 contains an air flow measuring device 8 which is arranged directly in the air duct 4 and therefore measures the total air flow for the engine 6. The measuring device 8 causes air vibrations to be generated at a frequency proportional to the air flow speed. These vibrations. are with the help of a pressure or flow sensitive element; which forms part of the measuring device ti , converted into electrical pulses. The measuring device 8 thus generates electrical pulses with a frequency which is proportional to the measured air flow rate.

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The output signal of the measuring device 8 passes through a Line 10 to a control device 12. The control device 12 is also supplied with information, for example via the line 14 information about the acceleration of the engine, via the line 16 information about the air temperature in the air duct 4, about the line 17 information about the battery output voltage and about line 19 information about the temperature of the engine coolant. The air and coolant temperatures can can be measured by means of appropriately attached thermistors. When the engine is cold, more fuel can be used may be required so that an air damper function is obtained. When the vehicle accelerates it will intermittently more fuel is required to ensure freedom from the dead centers of the engine. This can be done with the help of a sensor for the speed of movement of the accelerator pedal can be achieved, which ensures that the fuel-air ratio is increased when the driver of the vehicle requests acceleration by the transmission of corresponding electrical signals via the line 14 is caused.

The control device 12 is thus supplied with information that is important for the ratio of fuel to air that the engine requires. The control device 12 then generates a corresponding sequence of square-wave pulses with a predetermined duration on the line 18, which causes the exactly correct amount of fuel to be injected into the air duct 4 from an injection device 20. The duration of these impulses is primarily determined by the air flow

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speed in the air duct h is determined, but it is modified by the above-mentioned control parameters v / ie the engine acceleration and the air and coolant temperatures.

The duration of the pulses can also be determined by an optionally available oxygen sensor 11 in the exhaust gas duct 13 of the engine to be changed. The oxygen sensor 11 monitors the Oxygen content of the exhaust gases, and it provides a signal on the line indicating the air / fuel ratio that the engine is working. This signal is input to the control device 12 via the line, and it can do so serve to indicate the required air / fuel ratio. During acceleration and deceleration of the motor 6 is the signal from the oxygen sensor normally overridden by the sensor for the accelerator pedal position, so that temporary changes in the air / Fuel ratio are allowed. This ensures that the Vehicle is maintained when acceleration is required and that during deceleration minimum amount of fuel is provided.

The injector 20 is a vibration injector Facility; line 18 is connected to a piezoelectric crystal 22 which is part of the injector is. The electrical signals actuate the piezoelectric crystal 22 and the injector is made to vibrate. The fuel injected by the vibrating injector is in the form of a spray jet. The vibrations, which are preferably in the ultrasonic range are located in the horn section 24 of the injector 20 reinforced. Usually located

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In the tip 26 of the horn section 24 there is an opening which is closed with the aid of a non-return valve is. The check valve is preferably a ball valve. If a ball valve is used, this valve is preferably mounted in its own housing in the nozzle tip, and this housing can have different openings be provided so that a turbulence of the fuel is caused in the housing and thus also effected is that the fuel in the housing pushes the ball valve against the nozzle opening.

From Figure 1 it can be seen that in the air duct 4 adjacent an end 28 of a heat pipe 30 is arranged on the injection device 20. The presence of the heat pipe 30 is not absolutely necessary. The other end of the heat pipe 30 is arranged in the exhaust manifold 34 of the engine 6. The heat pipe 30 is a closed container holding water or other vaporizable material, for example Sodium, may contain. The vaporizable material is at the end 32 of the heat pipe due to the in the exhaust manifold 34 existing hot gases evaporated. The vaporized material then travels along the heat pipe 30 to end 28. The end 28 is cooler than the vaporized material, and this vaporized material gives off its heat to the end 28, and condenses again. The recirculated material flows along a (not shown) Wick within the heat pipe 30 back to the end 32, where it evaporates again. The one handed in at the end of 28 Heat contributes to the evaporation of the fuel injected from the injector 20. The one from the nozzle of the Injector 20 injected fuel can be on the

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meet the hot end 28 of the heat pipe, if so desired. The injected fuel can also be in a general hot area that has been heated by the heat pipe. The completely vaporized and properly mixed The fuel-air mixture can then be passed through a normal throttle valve 36 for combustion to the engine 6.

In FIG. 2, one of the apparatus of FIG. 1 is identical Device shown, wherein the same parts are provided with the same reference numerals. In the one shown in Fig.2 Embodiment can be seen that the Luftströmungsmeöeinrichtung 8 is not attached in the main air flow channel 4, but in a secondary flow channel 50. The air flow measuring device 8 thus measures part of the air ultimately intended for motor 6,

Injector 20 and heat pipe 30 are also mounted in channel 50. The full amount of fuel the Engine is required, is injected by the injection device 20 into the air in the channel 50. This mixture of fuel and air is then fed back into the main channel 4 at the opening 52, and the correct fuel-air mixture then passes the throttle valve 36 to the engine 6. In the main channel 4, a constriction 33 can optionally be used, so that it is ensured that a constant The ratio of the air flow through the main channel 4 and through the secondary flow channel 50 is present.

In Figure 3 a device is shown, which in the Figures 1 and 2 are the same devices shown; the same parts are provided with the same reference numerals. In the Embodiment of Figure 3 can be seen that the air

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Flow measuring device 8 is arranged in the secondary flow channel 50 while the injector 20 and the heat pipe 30 are mounted in the main channel 4.

In the embodiment shown in ag.3 it can It may be desirable to obtain an air to fuel ratio of 16: 1 or 17: 1. The line 18 pulses transmitted to actuate the injection device 20 can also include pulses at stall speeds of the engine the duration of one millisecond.

From Figure 3 it can be seen that the control device 12 is formed from two separate units, namely from a monostable device 12A and an oscillator 12B, for example of the type described in patent application P 26 41 921.6. The one-shot device 12A receives from the air flow measuring device 8 electrical pulses, the frequency of which differs from that flowing in the secondary flow channel 50 Air volume is determined. The one-shot device 12A is also supplied with information that is the fuel-air ratio the combustion mixture for the engine 6 can influence. This information can be information about the accelerator pedal movement on line 14, information about the air temperature in duct 4 on line 16, a Information about the battery output voltage via line 17 and information about the engine coolant temperature be on line 19. The one-shot device 12A effects processing of the received Information, and it generates a train of pulses of a predetermined duration and at a frequency that corresponds to the Oscillator 12B trips for the required periods of time.

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Injector 20 injects as a result of activation by oscillator 12B for the required periods of time Fuel.

In three further embodiments of the invention, the fuel and air metering device can be designed so as shown in Figures 1 to 3, but the fuel vaporizing device 30 is not present is · In order to achieve effective fuel atomization, the devices according to FIGS. 1 to 3 then only made use of the atomization produced by the injection device 20.

If the devices shown in FIGS. 1 to 3 operate without an oxygen sensor 11, then preferably into the control device electrical signal shaping circuits built in to ensure that the desired amount of fuel is independent of non-linearities within the monitoring instruments or the engine 6 is supplied.

In Figure 4, the injection device 20 is from the piezoelectric Crystal 22 and the horn section 24 according to Figures 1 to 3 shown. The injector 20 is arranged in a bushing 60. The implementation 60 leads into a main air duct 62. The Feedthrough 60 has an inlet 64 and an outlet 66. A baffle 68 is preferably located in the outlet 66 arranged.

The bushing 60 bypasses the throttle valve 36. The bushing 60 is dimensioned so that it is of a sufficient size Amount of air flows through it so that the fuel

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is transported away from the atomizer tip into the main channel 62, but it is not so large that the motor can operate at idle without a small amount of air flowing through the throttle valve 36.

At low loads and speeds of the engine there is such a pressure ratio at the throttle valve that the flow of air through inlet 66 is restricted and the fuel accelerating through that inlet te lent and then extend while passing through the shock waves that are on the downstream side of the inlet 66 and the throttle valve 36 are generated, can be further decomposed.

At higher loads and speeds of the engine, the air flow is much more turbulent, and the need further atomization is less important.

It will be recognized that the various embodiments of the invention have been given by way of example only; Modifications can be done. For example, another type of injector 20 can be used. For example, the injection device 20 could be electromagnetically actuated, for example magnetostrictive Be establishment; it could also be a device without a check ball valve. It's just an injector, though 20, but multiple injectors can be employed if desired. in the For example, in the case of a V-8 engine, two injectors 20 could be used, one each Feed intake manifold for four cylinders. Also use

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a low flow rate injector 20 could be used for part of an engine operating condition while for another part the engine operating state in the same system an injection device 20 could be applied at high flow rates. For engine conditions with high speed and high load, both injection devices can be used.

At cranking speeds, the air drawn into the engine may not have the sufficient speed that a allows the air flow measuring device to work properly. Under these conditions, the injector controlled by the ignition pulses of the engine. When the output signal, for example, the air pulses from the air flow measuring device have a sufficient frequency, then the electrical Switch this on and it switches the control by the ignition pulses to the control by the air flow measuring device around.

The impact body can be replaced by a fluid-controlled component, the air alternately on two Distributed flow paths. The flow meter can be a temperature transducer with one or more thermistors be. Preferably these thermistors are planar thick film thermistors which extend over a substantial area. These thermistors are advantageously heated by the current which characterizes the air flow. In In some cases, the material of the thermistors may have such a high resistance as to heat the thermistors a separate heating circuit is required. In this case, the thermistors can be made from a ceramic block with a Heating circuit on one side and a thermistor material, /

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for example a paste or a paint, on the other hand. The own heating circuit generated enough heat to heat the ceramic block and transfer the heat through the block to the thermistor surface will. A separate current can flow through the heated thermistor and changes in that current can be measured caused by the cooling effect of the air pulses. The thermistors can be attached to the walls of an air duct of the motor or on the impact body.

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Claims (12)

270H47 Claims _ .. f 1 Λ fuel and air metering device for an engine, characterized by an air flow measuring device which measures at least part of the air flow for the engine and generates an electrical output signal proportional to the measured air flow, a control device which receives the output signal of the air flow measuring device and generates electrical output signals that change depending on the received signals, and an injection device that injects fuel depending on the signals received from the control device. 2. Apparatus according to claim 1, characterized in that the injection device is a vibrating injection device which is made to vibrate with the aid of a piezoelectric device. 3. Apparatus according to claim 1 or 2, characterized in that the air flow measuring device is a vortex shedding flow meter is. 4. Apparatus according to claim 3, characterized in that the flow meter contains a pressure transducer. 5. Device according to claim 3, characterized in that the flow meter contains a temperature converter. 6. Device according to one of the preceding claims, characterized in that the control device has a Contains monostable device that receives the pulses from the air flow measuring device and pulses with generated for a predetermined duration. 709829/0793 _ ORIGINAL INSPBTTED 7. Apparatus according to claim 6, characterized in that the control device contains an oscillator, and that the output pulses from the monostable device dem Oscillator are supplied, which causes the actuation of the injection device. 8. Device according to one of the preceding claims, characterized by a fuel atomizing device for atomizing at least a portion of the injected Fuel. 9. Apparatus according to claim 8, characterized in that the fuel atomization device is a fuel evaporation device is. 10. The device according to claim 9, characterized in that the fuel evaporation device is a V / poor pipe. 11. The device according to claim 8, characterized in that the fuel atomization device is a sonic nozzle. 12. The device according to claim 8, characterized in that the fuel atomization device has a flat surface that can be made to vibrate.