WO1991014091A1

WO1991014091A1 - Device for determining fuel througput in an internal-combustion engine

Info

Publication number: WO1991014091A1
Application number: PCT/AT1991/000039
Authority: WO
Inventors: Peter Frick; Adolf Jopp
Original assignee: Peter Frick; Adolf Jopp
Priority date: 1990-03-06
Filing date: 1991-03-06
Publication date: 1991-09-19
Also published as: ATA52490A; EP0471068A1

Abstract

The fuel-throughput determination device described has a measurement device (2) through which fuel is passed from the tank to the feed pump. Fuel is injected under pressure into the engine and pressurized fuel is returned, after passing through the measurement device (2), to the suction line of the pump, the returned fuel being passed, before it is fed into the pump suction line and after it is re-cooled in a heat exchanger, through a gas separator (3). The gas separator is designed as a pressure free reservoir with a bottom-located valve (25) linked to the tank by a gas return line (17). The gas separator (3) and the measurement device (2) are fitted together as a single assembly (1) so that heat is conducted from one component to the other. The bottom-located valve (25) opens out into a channel (18) located in the floor of the assembly (1) and linking the outlet (9) of the measurement device (2) with the suction line (5) of the pump, and the dimensions of the heat exchanger for re-cooling the uninjected recycled fuel are selected or the heat exchanger is adjusted such that the temperature of the fuel fed into the gas separator (3) is higher than the temperature of the fuel in the tank.

Description

Device for determining the fuel flow rate in internal combustion engines

The invention relates to a device for determining the fuel flow rate in internal combustion engines with a transmitter, via which fuel is conducted from the tank to a feed pump, fuel being injected under pressure into the internal combustion engine and pressurized fuel following a suction line of the feed pump is returned to the transmitter, furthermore the returned fuel is fed via a gas separator before being fed into the suction line of the feed pump after recooling in a heat exchanger and the gas separator is designed as a pressure-relieved store with a bottom valve via a gas return line to the tank.

A number of different systems have become known for measuring the fuel consumption of internal combustion engines in which the fuel is injected via injection nozzles. Due to the construction of injection pumps for such internal combustion engines, the non-injected portion of fuel that was previously made available to the injection pump is circulated and returned to the tank. In such a circuit, however, a transmitter, which is arranged in the suction line of a feed pump to such an injection pump, would measure the amount of fuel returned in each case several times, so that a second transmitter would be required to measure the amount flowing back into the tank to be considered subtractively.

A number of devices have already become known which avoid the use of two sensors, in principle the return of the quantity of fuel not injected by the injection pump into the injection nozzle Suction line of the feed pump takes place after the sensor. The returned fuel quantity is, however, heated relatively high by the compression stroke of the injection pump and a more or less large proportion of gas is also transported with the returned fuel quantity. Particularly high gas fractions, which can be attributed, among other things, to particularly high operating temperatures, result in Cummins engines. The recirculated gas portion leads to a significant reduction in the performance of the engine in the case of a simple circuit and therefore the measuring devices known hitherto tend to reduce the engine output due to the fuel recirculated with a high gas portion.

From DE-PS 29 32 014 it has already become known to use fuel pumps in internal combustion engines with fuel gauges, via which a part of the fuel quantity is circulated, a reflux tank being arranged in the circuit, which degasses the fuel being circulated enables. This reflux tank then opens into the suction line of the fuel pump via a float-controlled valve, this mouth lying in the flow direction after the dial gauge. In this known proposal, the degassing takes place largely without pressure and the gas space of the reflux tank is connected to the gas space of the fuel tank via a line. In the case of fuel injection rotors, comparatively much higher pump outputs and thus a much higher suction pressure are required, as a result of which the proposed, simple, float-controlled valves in the reflux tank do not appear to be usable without further ado. Particularly when using injection pumps which inject fuel under high pressure into the internal combustion engine, the fuel heats up considerably more than in simple fuel delivery pumps and is regenerated too high heated fuel in the suction line or in the internal combustion engine also leads to a drop in performance.

In another known fuel flow measuring unit, such as that sold by the company AIC Systems AG, the amount of leak oil or reflux is returned to a degassing chamber when using injection pumps, which, however, has to be manually vented, since automatic venting is not provided here is. Also, in this known device, the recirculated fuel is not recooled, so that the problems indicated above can also arise here, particularly in the case of injection pumps with high working pressure.

It has become known to provide heat exchangers for recooling the fuel which is circulated and withdrawn from the leakage oil line or the overflow valve of a distributor pump. Such a proposal has become known from a brochure from Mannesmann Kienzle GmbH, the heat exchanger being supplied with cooling medium via a separate electric pump. In this known arrangement, a gas separator is also arranged in the overflow line, with this proposal, analogously to the proposal in DE-PS 29 32 014, which was principally not intended for diesel injection pumps, the gas separator via one into the gas space of the gas line leading to the tank is depressurized.

All known devices have in common that the temperature of the fuel which is supplied to the engine is highly dependent on the ambient temperature, and that there are therefore climate-related distortions in the measurement. A different fuel temperature also leads to changes in engine performance and to operating conditions that are more unfavorable depending on the outside temperature with regard to emissions behavior. The invention now aims to provide a device of the type mentioned at the outset which, in different climatic conditions, in particular with changing outside temperatures, rapidly ensures a desired fuel temperature for injection into the internal combustion engine, which is easily retrofitted without any special installation effort existing internal combustion engines or combustion power plants can be retrofitted or installed, and which in no way impairs the engine performance, but rather keeps them constant at the level which is most favorable for the emission behavior. To achieve this object, the device according to the invention essentially consists in that the gas separator and the transmitter are arranged in a thermally conductive manner in a common component, that the bottom valve opens into a channel running in the bottom of the common component, which channel connects the output of the transmitter with the Suction line of the feed pump connects, and that the heat exchanger for the recooling of the non-injected, recirculated fuel is dimensioned or regulated so that the temperature of the fuel fed into the gas separator is higher than the temperature of the fuel in the tank. Characterized in that the gas separator and the transducer are thermally conductively connected together in a common component, an integrated component is created, which can be retrofitted relatively easily with little installation effort. Due to the thermally conductive connection of the measuring device and the pressure-relieved memory for the reflux quantity, the entire assembly with the dial gauge or the transducer is heated relatively quickly after starting operation, so that even at extremely low outside temperatures, especially when using diesel fuel, flocculation of the paraffin contained in the fuel, which could cause filters to be laid, is avoided The relatively quick reaching of the operating temperature of the internal combustion engine The fuel to be supplied significantly improves the performance characteristics and the emission behavior of the internal combustion engine, particularly in operation immediately after starting, and in that the recirculated fuel which is not injected and circulated is recooled to a temperature level which is above the Temperature level of the fuel in the tank, optimized operating conditions can be maintained in every operating phase. Overall, a compact, small-sized structural unit is created which can be arranged anywhere in the engine compartment, the installation work being essentially restricted to the suction line of the feed pump being guided over the dial gauge or the measuring value transmitter and the overcurrent line is not connected directly to the tank, but with the tank being connected with the storage. It is therefore usually only necessary to separate two existing lines into which the compact unit is switched on. At the same time, the display accuracy of the device is significantly increased in that the transmitter is also kept at a largely constant temperature. The distortions of the measured quantity which are dependent on climatic conditions in the usual arrangements of dial gauges can be eliminated in this way without complex temperature measurements and arithmetic compensations, which results in a particularly simple and reliable evaluation circuit.

To improve the operating behavior of the downstream internal combustion engine, the device according to the invention is advantageously designed such that the fuel returned to the gas separator is recooled to above 35 ° C., preferably 40-50 ° C. Compared to known measuring devices, such an adjustment means an adjustment of the temperature level of the fuel quantity to be supplied to the injection pump to temperatures which are about 3 to 8 ° C. above the usual values, which results in a clear Improvement in performance and emissions behavior results. Furthermore, such a design requires less effort in the arrangement or design of the heat exchanger. In known devices, the placement of the heat exchanger has proven to be critical in some cases. At the same time, the increase in the temperature level means that the dial gauge or the transmitter is also operated at a relatively higher temperature, and since the viscosity of the fuel decreases at a higher temperature, correspondingly more sensitive transmitters can be used, making a more precise measurement possible.

A relatively sensitive sensor can be designed in such a way, as it corresponds to a preferred embodiment of the device according to the invention, that the sensor is designed as an eccentric piston pump, the number of revolutions of which is via a non-contact sensor, e.g. a magnet and a reed contact are supplied as pulses to an evaluation circuit, a simple evaluation circuit being able to be used in particular due to the contactless removal of pulses and impairments of the fuel flow being largely eliminated by the measuring device.

In the subject of DE-PS 29 32 014, a bottom valve has already been proposed in the unpressurized memory, which is actuated by a float inside the vessel. In particular, in the case of a high pressure difference between the unpressurized accumulator and the suction line of the downstream feed pump, such simple float valves can no longer be actuated easily, since the valve must open against the suction pressure in the suction line of the downstream feed pump. According to the invention it is therefore proposed, in order to increase operational safety, that the bottom valve is designed as a float valve in which the closing member is connected to the floating body via a lever transmission. While with float valves, which against a high Do not open the suction pressure properly anymore, there is a risk that the fuel that is circulated will not get into the suction line after the dial gauge, but will instead be led back into the tank via the gas line and thus be measured twice, the proposed lever transmission leads to a safe one open the valve, whereby the degassed fuel quantity is actually re-introduced into the circuit after the dial gauge.

In principle, the device according to the invention ensures a high degree of operational reliability even at low outside temperatures. However, in order to ensure safe operation of the internal combustion engine even if the fuel consumption is not measured in the event of a malfunction of the transmitter, the design is advantageously made such that the input and the output of the transmitter are connected to one another via an open by-pass line are connected, the input and the output of the sensor preferably being separated from one another by a partition provided with an opening, in which opening a releasable closing element is arranged. In these cases, it is sufficient to open the by-pass line in the event of a failure of the sensor, as a result of which the fuel flow from the tank to the injection pumps can be maintained and the advantages of a pressureless degassing while the temperature level is increased are maintained.

In order to reliably prevent the fuel fed into the intake line from the unpressurized accumulator from kicking back at high pressure differentials to the sensor arranged in the same component and thus spatially adjacent, the design is advantageously made such that the suction line of the feed pump connects to one is connected to the valve opening of the bottom valve aligned channel, and that the connecting line integrated in the housing from the transducer into the suction line in this channel near the bottom valve opens in a substantially radial direction, the risk of backward shear can be further reduced if the cross section of the connecting line is smaller than the cross section of the channel to which the suction line is connected. The cross-sectional ratio can easily take into account the fact that up to 75% of the fuel is circulated through the leakage oil line or the overflow line of the pump, in which case the cross-section of the connecting line is about 1/4 to 1 / 3 of the cross section of the channel to which the suction line is connected.

The device according to the invention is explained in more detail below with reference to exemplary embodiments schematically illustrated in the drawing. 1 shows a schematic representation of an internal combustion engine with the device according to the invention for determining the fuel flow rate; 2 shows a first embodiment of a device according to the invention for determining the fuel flow rate, and FIG. 3 shows a modified embodiment of a device according to the invention for determining the fuel flow rate in a more detailed illustration compared to FIG.

In FIG. 1, 1 denotes a device according to the invention for determining the fuel flow rate, which consists of a common component in which a sensor 2 and a gas separator 3 designed as a pressure-relieved memory are integrated. A feed pump 4 in the fuel line 5 conveys fuel from a storage container or tank 6 via a pre-filter 7 through the sensor 2 shown in more detail in FIGS. 2 and 3, the supply of fuel into the sensor being shown schematically by the arrows 8 and the feeding of fuel into line 5 from the sensor is indicated schematically by 9. The fuel delivered by the feed pump 4 enters a schematically indicated injection pump 10, wherein individual, not shown cylinders of the combustion engine associated injection nozzles are indicated with 11. A certain percentage of the fuel supplied by the feed pump 4 to the injection pump 10 is fed via a return line 12 to a heat exchanger 13 provided in the storage container or tank in the illustrated embodiment, with a relatively high cooling of the fuel returned from the injection pump 10 in the heat exchanger Fuel having temperature to temperatures between 40 and 50 ° C takes place. From the heat exchanger 13, the cooled fuel is fed via a line 14 to the gas separator 3 via a feed line 15, with a relative pressure relief for the gas accumulator 3 and for degassing of the gas pump, which is fed via the injection pump, depending on the type of engine used and the injection pump High gas content fuel, a degassing line 16 is connected to a connection 17 of the memory, the degassing line 16 opening into the reservoir or tank 6. As explained in more detail in the following figures, the gas separator or accumulator 3 has a bottom valve and the gas separator 3 is recirculated to the fuel circulated into the delivery channel 18 integrated in the common component 1, as indicated schematically by arrow 19 is.

In the illustration according to FIG. 2 it can be seen that the common component 1 for the device according to the invention enables a thermally conductive connection of the transmitter 2 or the dial gauge with the gas separator 3 designed as a pressure-relieved memory. The fuel sucked in via the feed pump, not shown, passes via the feed 8 into an eccentric piston pump 20, the piston 22 of which is rotatably mounted about an axis 21 for measuring the fuel quantity via a non-contact sensor, as is shown in more detail in FIG the Flow rate of the fuel allows. The output of the transducer is again designated 9 and opens into the channel 18 running in the bottom of the common component, to which the delivery line 5 connects. Immediately next to the transmitter, the gas separator is provided in the common component 1, to which the recirculated fuel which is cooled to temperatures of over 35 ° C., in particular between 40 and 50 ° C., is fed under pressure. The connection for the degassing line is again designated 17. A float valve is provided in the interior of the gas separator, with a float 23 allowing the schematically indicated valve cone 24 of the bottom valve 25 to be lifted off at a correspondingly high fill level, so that the fuel degassed in the gas separator 3 via the opening 19 to the common channel 18 Feed pump is supplied.

The fuel is recooled to temperatures above 35 ° C., in particular 40 to 50 ° C., these temperatures each being above the temperature of the fuel in the tank or storage container 6, to a temperature level which is optimal and economical Emission behavior of the internal combustion engine enables. Characterized in that the gas separator with the fuel located in a favorable temperature range is integrated in a thermally conductive manner with the transmitter or the dial gauge 2 directly in a common housing, the tank or reservoir, which is guided via the transmitter 2, is heated 6 drawn fuel to likewise optimal temperature and it is possible to dispense with additional heating of the fuel, in particular with these fuels, since when the injection pump is in operation, due to the high compression of the fuel, the fuel already reaches a very high temperature immediately after starting and the returned fuel , which can amount to up to 75% of the total amount of fuel delivered by the feed pump 4, has a sufficiently high temperature to the to heat common component 1 and thus the dial gauge or the transducer to temperatures of over 35 or over 40 ° C. in the shortest possible time. At such high temperatures of the fuel, even in the case of diesel fuel, no component failures occur, so that clogging or laying of filters, in particular, can be ruled out with certainty. It also ensures that a fuel temperature that is favorable for optimal engine performance can be set within a very short time after starting.

In the modified embodiment shown in FIG. 3, the transmitter 2 and the gas separator 3 are in turn integrated in the common component 1 in a thermally conductive manner. An eccentric piston pump 20 is again used as a sensor. The contactless sensor comprises a magnet 26, a reed contact 27 and the signals corresponding to the number of revolutions of the piston 22 and taken off via a reed contact are fed via lines 28 to a line connection 29 to an evaluation circuit (not shown in more detail).

The fuel drawn in via the feed pump (not shown in detail) passes through the prefilter 7, which is fixed to the common component 1, again via the input 8 into the eccentric piston pump 20 and is output to the common via the output 9 from the transmitter via a connecting line 30 seeds, provided in the bottom of the component 1 channel 18, to which the connection for the delivery line 5 opens. In the embodiment shown, the valve opening of the bottom valve 25 of the gas separator 3 opens flush into the channel 18 and this channel 18 has a larger diameter than the diameter of the connecting line 30, as a result of which the degassed fuel discharged from the gas separator 3 flows back Direction to the transmitter is reliably prevented and furthermore the fact is taken into account that in general one the amount of fuel supplied via the sensor 2 is passed in a circle.

In the embodiment shown in FIG. 3, a float valve is again provided, the valve closing member 31 formed by a ball being connected to a floating body 34 via a lever transmission 32 and 33. The pivot axis of the lever 33 on the housing of the gas separator 3 is denoted by 35 and the lever 32 is articulated on the lever 33 about the axis 36. With a corresponding increase in the fill level of the gas separator 3, the float reaches the position schematically indicated by 34 *, as a result of which the valve closing member 31 reaches the position 31 'indicated by the broken line and in this way fuel flows out of the gas separator 3 into the channel 18 and in

The fuel is returned to the gas separator 3 in the area of the cover of the gas separator in a different plane from the cut shown and is again indicated at 15, while the connection for the degassing line is again indicated at 17 Even if the bottom valve 25 jams or malfunctions, there can be no malfunctions in the internal combustion engine, since in this case the returned fuel is returned to the tank or storage container via the degassing line, so that the latter If there is only a multiple measurement of the fuel.

In order to ensure safe operation of the internal combustion engine even if there is a defect in the sensor, even if the amount of fuel consumed is not measured, an open by-pass line is provided between input 8 and output 9 of the sensor. In the embodiment shown, the connecting line 37 aligned with the connecting line 30 between the prefilter 7 and the input 8 of the Transducer switched on a partition from which a removable closing member 38, which may be in the form of a slide, for example, is removed when the transducer becomes defective, whereby a possibly occurring blockage of the fuel flow in the event of a defect in the transducer can be avoided. In this way, an interruption of the fuel flow from the tank 6 via the sensor and the common component 1 in the event of the sensor being damaged is avoided.

In order to avoid duplicate measurements, the returned fuel from the gas separator 3, as can be clearly seen in the exemplary embodiments, is in turn fed to the feed line to the feed pump after each transmitter 2. Instead of the heat exchanger provided directly in the tank in the exemplary embodiment in FIG. 1, another embodiment or arrangement of this heat exchanger can of course also be provided. With a direct arrangement of the heat exchanger in the tank, however, there is at the same time the possibility of preheating the fuel to a certain degree already in the tank at low temperatures, whereupon the sensor is raised to an optimum temperature level. In addition to heating the fuel as it passes through the sensor, the thermally conductive connection of the gas separator to the sensor ensures that the sensor operates in a relatively narrow temperature interval, so that after calibration has been carried out it is so tight Limited temperature interval, the display and measurement accuracy of the entire device can be increased without the aid of temperature compensation circuits or correspondingly complicated evaluation circuits, although the temperature of the fuel drawn from the fuel tank or tank 6 varies over a relatively wide temperature range in accordance with the external conditions can.

Claims

Claims:

1. Device for determining the fuel flow rate in internal combustion engines with a transmitter (2), via which fuel from the tank (6) is passed to a feed pump (4), fuel being injected under pressure into the internal combustion engine and pressurized fuel from a suction line of the feed pump (4) is returned after the measuring value transmitter (2), the furthermore the returned fuel before being fed into the suction line (5) of the feed pump (4) after recooling in a heat exchanger (13) via a gas separator (3) and the Gas separator (3) is designed as a pressure-relieved accumulator with a bottom valve (25) via a gas return line to the tank (6), characterized in that the gas separator (3) and the transmitter (2) are arranged in a common component in a thermally conductive manner are that the bottom valve (25) in a channel running in the bottom of the common component (18) opens, which connects the output of the sensor (2) to the suction line (5) of the feed pump (4), and that the heat exchanger (13) is dimensioned or regulated for the recooling of the fuel which is not injected and is circulated that the temperature of the fuel fed into the gas separator (3) is higher than the temperature of the fuel in the tank.

2. Device according to claim 1, characterized in that the fuel returned to the gas separator (3) is recooled to above 35 ° C, preferably 40-50 ° C.

3. Device according to claim 1 or 2, characterized gekennzeich¬ net that the transmitter (2) is designed as an eccentric piston pump (20), the number of revolutions via a contactless sensor, such as a magnet (26) and a reed contact ( 27), as pulses to an evaluation circuit.

4. Device according to claim 1, 2 or 3, characterized gekenn¬ characterized in that the bottom valve (25) is designed as a float valve, in which the closing member is connected to the floating body (34) via a lever transmission (32, 33).

5. Device according to one of claims 1 to 4, characterized in that the input (8) and the output (9) of the transmitter (2) are connected to one another via an apparent by-pass line (38).

6. Device according to claim 5, characterized in that the input (8) and the output (9) of the transmitter (2) are separated from each other by a partition provided with an opening, in which opening a releasable closing member (39) is arranged.

7. Device according to one of claims 1 to 6, characterized in that the suction line (5) of the feed pump (4) to one with the Ventilδffnung the bottom valve (25) cursing channel (18) is connected, and that in the housing Integrated connecting line (30) from the transmitter (2) opens into the suction line (5) in this channel (18) near the bottom valve (25) in a substantially radial direction.

8. Device according to claim 7, characterized in that the cross section of the connecting line (30) is smaller than the cross section of the channel (18) to which the suction line (5) is connected.