KR20180071298A

KR20180071298A - Method for determining one or more fuel properties

Info

Publication number: KR20180071298A
Application number: KR1020187013686A
Authority: KR
Inventors: 마크-플로리안 펠만; 메틴 겡크바이
Original assignee: 로베르트 보쉬 게엠베하
Priority date: 2015-10-19
Filing date: 2016-10-11
Publication date: 2018-06-27
Also published as: WO2017067814A1; CN108138685A; DE102015220327A1

Abstract

The present invention relates to a method for determining at least one characteristic of a fuel in an injection system of an internal combustion engine, wherein the injection system comprises a first injector (10) and at least one second injector (10) The pressure profile in the region of the high-pressure supply line 15 of the first injector 10 is set to be higher than the pressure profile of the high-pressure supply line 15 of the first injector 10 in order to detect the operation of at least one of the two injectors 10 and accordingly determine one or more characteristics of the fuel, And evaluated.

Description

Method for determining one or more fuel properties

The present invention relates to a method for determining at least one characteristic of a fuel and to an apparatus for carrying out the method.

An injection system in an internal combustion engine is used to transfer fuel from the tank into the combustion chambers of the internal combustion engine, i.e., the cylinders, and to inject the fuel into the combustion chambers. In the case of a common rail injection system, the fuel is at a high pressure level by the high pressure pump. The pressurized fuel enters the tube line system, i.e., the rail, and the pressurized fuel is again supplied to the injectors for injection from the tube line system. The common rail injection principle is characterized by a complete separation of the pressure generation and the actual injection process. The actual injection is carried out through the driving of the injector, which is also referred to as a injection valve, for example, by driving using an electrical signal, i.e., a driving signal. Generally, it is divided into solenoid valve and piezo injection valve including piezo actuator according to the function principle.

Injectors, also referred to as injection valves, basically include a nozzle body and a nozzle needle. In the non-driven state, the nozzle needle is brought into close contact with its seat, and the fuel is not injected. When the nozzle needle is moved by driving, the injection valve is opened and fuel is injected. The nozzle needle is moved from the closed position to the needle turning point where the nozzle needle is moved farthest from its rest position at the time of needle opening and then moved to its rest position at the needle closing time . In this case, the driving period directly acts on the injection amount.

In addition, the injection quantity in the common rail system (CRS) depends on various fuel characteristics, which again depend on the type of fuel and the ambient conditions. For example, fuel properties are the viscosity of fuel grades, such as winter diesel, arctic diesel, bio diesel, mixed grades of various fuel grades, and are further temperature dependent. The effects of these characteristics on the amount may be insufficiently corrected or never corrected, for example, unless there is a possibility to determine important fuel properties through the sensor, for example, in the CRS.

From the German publication DE 10 2011 005 141 A1, a method for determining at least one characteristic of a fuel is known. In the case of the German publication, the closing period of the armature of the solenoid valve moved through the fuel is measured during at least one driving period. Based on the measured closure period, a factor representing one or more characteristics is calculated. The method is particularly used for determining the viscosity of the fuel.

Common rail injectors, including piezo actuators, are injectors whose pressure in the control chamber is varied by switching servo hydraulic valves. The control chamber is located just above the nozzle needle. In order to open the injector, the pressure in the control chamber is reduced until force equilibrium is achieved at the nozzle needle and the needle is opened, based on the perfusion of the exhaust and feed throttles. In this case, the switching valve unblocks the chamber behind the discharge throttle toward the low pressure region, whereby the control amount can be discharged from the control chamber into the low pressure portion via the discharge throttle. The control amount is released while the switching valve is open. See FIG. 1 for this.

In order to meet increasing emission emission and performance requirements, injector injector and injector functions must be kept as constant as possible over the immediate service life.

In this case, an important factor for achieving the above requirement is the determination of the amount of fuel injected through the CR injectors and the precision of the viewpoint, and the characteristics of the fuel. In order to be able to calculate the time of injection and the amount of fuel over the useful life, sensors are planned to be mounted on future common rail injectors to detect the time of "needle opening" and "needle closure"

German publication DE 10 2014 204 746 A1 describes a common rail injector which comprises an injector housing in which a high pressure chamber is formed in which a pressurized fuel can be supplied via a supply bore or a high pressure bore formed in the injector housing . On the outer surface of the injector, a sensor is provided which is capable of detecting a pressure drop in the high pressure bore as a result of the injection.

In the context of the prior art, a method according to claim 1 and an apparatus according to claim 10 are proposed. The embodiments are clearly set forth in the dependent claims and the following description.

The proposed method utilizes the elastic deformation in the gripping body in the region of the high pressure bore due to the pressure wave in the high pressure bore to determine the characteristics of the fuel used at the time of determination over the operating time during operation.

In this case, the pressure profile, particularly in the high pressure bore or high pressure supply line of the injector, is used for the detection of needle opening and needle closure of other injectors located in the system in the internal combustion engine, as a result of inferring the fuel characteristics. The deformation of the gripping body or line is used as a detection target variable. The sensors required for this purpose can be mounted on the gripping body or the supply line and need not be mounted anywhere in the high pressure and low pressure parts of the injector. Thereby, the operation of the other second injector is detected by the sensor on the first injector, and one or more characteristics are deduced over the detected operating time causing the delay. Since the time at which the other second injector is operated is a known matter, a delay or an operation time is derived from the time point at which the operation is detected at the first injector.

Through the detection and subsequent analysis of the time points of needle opening, inferences can be made about the characteristics of the fuel during operation over the operating time, in particular through the operating time to be calculated in this way. As a result, emission emission requirements and performance requirements can be adhered to. In addition, the supply of unfavorable fuel can also be detected.

The present invention proposes to determine or measure needle opening and / or needle closure of a plurality of neighboring injectors in an engine so as to be able to deduce fuel characteristics with the resulting information. Presently, for future CR injectors, including piezo actuators, separate sensors are provided for each injector to detect needle opening and needle closure of the injector. Corresponding functionality may also be implemented through the use of one or more injectors equipped with sensors.

The present method is also suitable for checking the functioning principle of a sensor provided on a high-pressure accumulator or rail of a jet system, that is, a so-called rail pressure sensor, and for validating the result. In this case, it is utilized that the pressure has a very large effect on the operating time. Accordingly, the detected operating time greatly depends on the pressure. The present method can also be used when there is a failure in the rail pressure sensor because the pressure and hence the rail pressure can also be indirectly determined through the evaluation of the operating time by the method of the present invention.

The proposed device is used for the execution of the method of the invention, for example integrated into the control device.

Further advantages and embodiments of the present invention are evident from the following description and the accompanying drawings.

As a matter of fact, the features referred to above and still to be described below can be used in combination with each other, as well as other combinations, or independently, without departing from the scope of the present invention.

1 is a view showing an embodiment of an injector for carrying out the method described.
Figure 2 is three graphs showing the profiles of the variables.
3 is a cross-sectional view showing the gripping body of the injector cut off.
Figure 4 is a graph showing profiles of measured variables.

The invention is schematically illustrated in the drawings in accordance with embodiments and is described in detail below with reference to the drawings.

1 shows an embodiment of an injector, indicated generally by the reference numeral 10, In the figure, the switching valve 12, the switching valve chamber 14, the throttle plate 16, the exhaust throttle 18, the supply throttle 20, the control chamber 22, the control chamber sleeve 24, 26 are shown.

Also shown in the figure is a high pressure supply line 15 which is guided by a high pressure bore 17 and a gripping body 19 is arranged in the region of the high pressure bore. On the gripping body 19, there is disposed a piezoelectric element 21 which records the deformation of the gripping body 19, in particular the deformation profile of the gripping body 19, while being used as a sensor.

In the case of the illustrated injector 10, through switching the servo hydraulic switching valve 12, the pressure in the control chamber 22 is varied. The control chamber 22 is located just above the nozzle needle 26. The pressure in the control chamber 22 on the basis of the flow of the exhaust throttle 18 and the supply throttle 20 is adjusted so as to open the nozzle needle while achieving force balance on the nozzle needle 26 . In this case, the switching valve 12 unblocks the chamber behind the exhaust throttle 18, which is directed to the low pressure region, whereby the control amount is controlled by the control chamber 22, via the exhaust throttle 18, Can be discharged. The control amount is discharged while the switching valve 12 is opened.

The opening of the switching valve 12 causes a pressure drop in the high-pressure supply line 15 and the high-pressure bore 17. The pressure drop in the high pressure bore 17 also causes the elastic deformation of the high pressure bore 17 and the elastic deformation of the gripping body 19 and this elastic deformation is measured through the piezoelectric element 21 used as the piezo sensor member And is transmitted to the control device 23 via the electric line 25.

In the case of the proposed method, from now on, the elastic deformation of the high pressure bore 17 and the elastic deformation of the gripping body 19 caused by the operation of the other injectors are also recorded and evaluated. Because the injectors are hydraulically connected to each other, the operation of one of the other injectors also acts on the pressure profile in the high-pressure supply line 15 of the other injectors. In this case, for example, a delay occurs due to the operation time. The delay is evaluated to yield one or more characteristics, e.g., viscosity.

Alternatively, or in addition thereto, a sensor, for example a piezo-electric element, may be arranged on the high-pressure supply line 15.

In Fig. 2, the signal profiles are shown in three graphs each over a corresponding time period. In the first graph 30, the profile of the drive voltage 32 over time is shown. In the second graph 40, the pressure profile 42 in the high pressure supply line over time is shown. In the third graph 50, the filtered voltage signal 52 on the input of the control device of the piezoelectric element arranged on the gripping body in the region of the high-pressure supply line is shown.

In the first graph 30, the driving period 34 is confirmed from the first point of time 35 to the second point of time 36 at which the driving of the injector is terminated. The point 38 on the profile 32 is indicative of the value of the drive voltage that is closed-loop controlled by the practice of the method described herein.

A pressure drop in the high pressure supply line occurs at the third time point (44) when the switching valve is opened and consequently the control amount is discharged. The pressure drop leads to a mechanical load relief of the gripping body on the circumference of the high pressure bore, i. E. On a polished section where the sensor is seated thereon. The load relief can lead to load reduction of the pre-pressurized piezoelectric element, for example, when the piezoelectric element is used as a sensor, and can be measured as a voltage change amount on the piezoelectric element.

When the nozzle needle is open, an additional pressure drop occurs in the high pressure line at the fourth time point (46). The pressure drop leads to an additional mechanical load relief of the gripping body on the periphery of the high pressure bore or on the polishing section where the sensor is seated thereon.

The load relief leads to an additional load relief of the pre-pressurized piezoelectric element and can be measured as the amount of change in voltage on the piezoelectric element. In this case, the fourth time point 46 may be defined and detected through a gradient change of the voltage change amount of the sensor.

At the needle closure, a pressure wave or pressure rise occurs in the high pressure bore at the fifth time point (48). The pressure rise leads to an additional preload of the sensor member and can be measured as the amount of voltage change on the sensor member.

Also, upon needle opening of the injector, a pressure drop occurs in the high pressure bores of other injectors in the common rail injection system, because the injectors are hydraulically connected via the rails and HD lines (HD: high pressure) to be. The pressure drop is shifted in time relative to the top dead center of the injecting injector, due to the relatively longer hydraulic section, reaching the other injectors. The computer unit of the CR system, which is accommodated, for example, in the proposed device, through a predetermined geometry of the injectors, the high-pressure line and the rail, and through the displacement of the viewpoint of the signal caused by the needle opening of the injector being driven, Using the information of the sensors and the cross-comparison of the information supplied by the sensor of the injector injector, it is possible to calculate actual fuel properties.

Through the injected geometry of the injectors, the high pressure line and the rail, and through the displacement of the point of view of the signal caused by the needle closure of the driven injector, the computer unit of the CR system is able to detect the information of the various sensors, The actual fuel characteristics can be calculated using a cross-comparison of the information supplied by the sensor of the injector.

In this case, it should be noted that parameters such as temperature, pressure and type of fuel (for example, diesel for summer, diesel for winter) affect the speed of sound waves. Through the time displacements and their variations during operation, the fuel properties can be determined.

Accordingly, the pressure increase can be detected by other injectors that include sensors on the high pressure bore to convert the deformation of the gripping body due to pressure rise into electrical variables and transmit the corresponding signal to the computer unit of the common rail injection system .

In Figure 3, the gripping body, indicated generally at 70, is cut away and shown in cross-section. The figure shows a high pressure bore 72, a piezoelectric element 74 used as a piezo sensor member, a bracing ring 76 formed as tightly as possible, and an expansion region 78 on the polishing section of the gripping body 70, Respectively.

The deformation of the high pressure bore 72 due to the pressure wave causes deformation of the gripping body 70, and this deformation is again recorded by the piezoelectric element 74. In this case, in particular the time-dependent profile of deformation is recorded and evaluated.

In Fig. 4, the signals of the sensors generated on the cylinders through the current supply of the injectors of the different cylinders are shown. This concerns the entire 4-cylinder engine.

In the figure, reference numeral 100 denotes a current supply of the cylinder 1, reference numeral 102 denotes a current supply of the cylinder 3, reference numeral 104 denotes a current supply of the cylinder 4, and reference numeral 106 denotes a current supply of the cylinder 2. Reference numeral 110 denotes current free-wheeling of the cylinder 1, reference numeral 112 denotes a current reflux of the cylinder 3, reference numeral 114 denotes a current reflux of the cylinder 4, 2 < / RTI >

The operation of needle opening and needle closure due to current supply and current reflux is also shown in further profiles. In this manner, the additional profiles include a pressure profile 130 on the first cylinder, a pressure profile 132 on the second cylinder, a pressure profile 134 on the third cylinder, and a pressure profile 136 on the fourth cylinder. Respectively.

The time delayed actions for pressure profiles 130, 132, 134 and 136 are also clearly identified.

Claims

A method for determining at least one characteristic of fuel in an injection system of an internal combustion engine, said injection system comprising a first injector (10) and at least one second injector (10), said at least one second injector The pressure profile within the region of the high-pressure supply line 15 of the first injector 10 is recorded and evaluated in order to detect at least one operation of the first injector 10 and thus determine at least one characteristic of the fuel, And determining the at least one characteristic of the fuel.

The method according to claim 1, wherein a deformation of the high-pressure supply line (15) of the first injector (10) is detected.

The method according to any one of claims 1 to 5, wherein deformation of the gripping bodies (19, 70) in the region of the high-pressure bores (17, 72) of the first injector (10) is detected.

4. A method according to claim 2 or 3, wherein deformation of the piezoelectric element (21, 74) is detected.

The method according to claim 1, wherein the pressure profile in the region of the high-pressure feed line of the first injector (10) is determined via a sensor detecting a pressure profile in the high-pressure accumulator (15) Way.

6. The method according to any one of claims 1 to 5, wherein the viscosity of the fuel is determined as a characteristic.

7. The method according to any one of claims 1 to 6, wherein the method is performed prior to cold start.

8. The method according to any one of claims 1 to 7, wherein the correction values for the driving period are calculated based on the determined at least one characteristic.

9. The method according to any one of claims 1 to 8, wherein the method is used to check the functioning principle of a pressure sensor provided on a high pressure accumulator of the injection system.

10. An apparatus for the execution of a method according to any one of claims 1 to 9, for determining at least one characteristic of a fuel in an injection system of an internal combustion engine, said injection system comprising a first injector (10) And at least one second injector (10) for detecting at least one of the at least one second injector (10) and for determining at least one characteristic of the fuel 1 injector (10) is configured to record and evaluate an in-zone pressure profile of the high-pressure feed line (15) of the fuel injector (10).