Air filter test arrangement and method for operating the air filter test arrangement

Abstract

Air filter testing arrangement with an air intake duct (22) of an air intake system (20) of an internal combustion engine (10), an air filter (40) which is arranged in the air intake duct (22), and a testing device (52) which, in the event of maintenance, can be temporarily mounted on at least one fluidic connection point (24) of the air intake duct (22) and can be fluidically connected to the air intake duct (22), wherein the connection point (24) is arranged downstream of the air filter (40) in the flow direction of the air flowing through the air intake duct (22), and wherein the testing device (52) is designed to determine a differential pressure between the two air pressures upstream of the air filter (40) and downstream of the air filter (40).

Description

The invention relates to an air filter test arrangement for functionally testing an air filter arranged in an air intake duct of the internal combustion engine.It is generally known from the prior art that an air filter is arranged in an air intake duct of an internal combustion engine through which the air required for the combustion process in the cylinders of the internal combustion engine flows from the external environment to the inlet valves of the cylinders. The air filter serves to filter dirt particles out of the intake air, thereby at least partially preventing dirt from being entrained into the cylinders by the air flow.During operation of the internal combustion engine or of the motor vehicle, the air filter is contaminated by the dirt particles filtered out of the air. In the case of a predefined degree of contamination of the air filter, the air mass flow flowing through the air filter and thus flowing to the cylinders of the internal combustion engine is no longer sufficient for operation of the internal combustion engine, as a result of which engine damage is imminent in the worst case. In particular, when driving in mats or in sand, the risk of a high degree of contamination or of clogging of the air filter is particularly high.The air filters are usually maintained or replaced during maintenance work of the motor vehicles carried out at regular intervals, i.e. after a predefined running performance of the motor vehicle or after a predefined period of time, for example two years, without the requirement for the replacement being checked. This has the result that air filters which are still intact are also exchanged and maintained. Otherwise, it may occur that an air filter achieves a high degree of contamination of an air filter that is harmful to the operation of the internal combustion engine, as for example, as mentioned above during travel through sand or slush, already before the predefined changeover intervals.In order to reliably ensure operation of the internal combustion engine and reliably prevent damage to the internal combustion engine, permanent monitoring of the air filter can be carried out by at least one pressure sensor being permanently arranged on the air intake duct and a differential pressure between the air pressures in the flow direction of the air flowing to the cylinders being determined before and after the air filter on the basis of the pressure sensor. The pressure sensor is connected in terms of signals to an evaluation unit, wherein the sensor signals of the pressure sensor are permanently evaluated and the differential pressure is determined. As a result, the mode of operation of the air filter is monitored permanently and a warm message is output in the event of a blockage of the air filter.The disadvantage of this is that each motor vehicle must have at least one pressure sensor and one evaluation unit, which serve exclusively for monitoring the air filter. This increases the manufacturing effort and the assembly effort of the motor vehicle.Different designs of air filter test arrangements are known from EP 1 070 841 A2, WO 97 / 06 363 A1, CN 2 14 887 415 U, U.S. Pat. No. 4,162,660 A and U.S. Pat. No. 2020 / 0 360 849 A1.The object of the invention is to propose an air filter test arrangement, by means of which a functional test of the air filter can be carried out in a simple and cost-effective manner. It is another object of the present invention to provide an air filter inspection arrangement which indicates replacement or maintenance of the air filter to a worker performing maintenance of the motor vehicle.The object is achieved by the features of claims 1 or 3.The air filter test assembly includes an air intake passage of an internal combustion engine and an air filter disposed in the air intake passage.According to claim 1, the air filter test arrangement has a test device which, in the event of maintenance, can be temporarily mounted on at least one fluidic connection point of the air intake duct and can be fluidically connected to the air intake duct. The fluidic connection point is arranged behind the air filter in the flow direction of an air flowing through the air flow channel.In the flow direction upstream of the air filter, ambient pressure normally prevails, since the air is drawn in from the environment. The test device is designed in such a way that a differential pressure between the two air pressures in the flow direction upstream of the air filter and downstream of the air filter is determined. For this purpose, the test device is connected on the one hand via the fluidic connection point of the air intake duct to the region of the air intake duct behind the air filter and on the other hand is connected fluidically to the region of the air intake duct in front of the air filter. The region in front of the air filter can be a region of the air intake duct which can be connected to the test device via a further connection point, or can be the external environment. The fluidic connection point is normally closed in an air-tight or gas-tight manner.It is decisive that the test device is mounted at the connection point exclusively temporarily or according to requirements, in particular in a case of maintenance of the motor vehicle, for example after a predefined time period or after a predefined driving performance of the motor vehicle or during a drive under certain external conditions, in particular during drives on sand or slush, and the differential pressure between the air pressures before and after the air filter is determined. On the basis of the differential pressure determined, it can be determined whether an exchange of the air filter is actually required. The testing device thus forms a tool for testing the air filter for its mode of operation.Such a test device can be used for different motor vehicles, wherein the motor vehicles only have to have one connection point or one connection piece.In this way, an air filter test arrangement can be provided, by means of which the differential pressure between the air pressures before and after the air filter can be determined as required and the requirement for an air filter change can thereby be determined in a simple and cost-effective manner.The test device is designed to display the determined differential pressure and / or a maintenance requirement of the air filter determined on the basis of the determined differential pressure. As a result, the differential pressure and / or the maintenance requirement is displayed directly on the test device temporarily mounted at the fluidic connection point. As a result, the worker who has mounted the test device to the connection point sees directly whether maintenance or replacement of the air filter is required. The test device has a differential pressure sensor with a digital display device.According to claim 3, the air filter test arrangement has a test device which is permanently mounted on the fluidic connection point of the air intake duct and is connected fluidically to the air intake duct. The test device comprises a display unit and is designed to determine a differential pressure between the two air pressures upstream of the air filter and downstream of the air filter in the flow direction and to display the differential pressure and / or a maintenance requirement of the air filter determined on the basis of the determined differential pressure. The test device has a differential pressure sensor with a digital display device.Because the test device has a display unit for displaying the differential pressure and / or the maintenance requirement required on the basis of the present differential pressure, an air filter that is no longer intact and possibly harmful for the operation of the internal combustion engine can be detected directly by the worker without having to separately connect a reading device or the like to the motor vehicle for this purpose. Based thereon, the worker can wait or replace the air filter, for example during a regular inspection, in which different operating means and filters are exchanged. In this way, maintenance can be facilitated.Alternatively, the test device has a housing with a first air connection and a second air connection, wherein the air connections are connected to one another via an air duct, wherein a translationally movable, spring-biased element is arranged in the air duct, which element separates the air duct into a region fluidically connected to the first air connection and a region fluidically connected to the second air connection, wherein the first air connection is fluidically connected to the air intake duct at the connection point and the second air connection is fluidically connected to the external environment, wherein the element or a display element which moves translationally with the element is visible from the outside and a marking for displaying the differential pressure or a requirement for a maintenance requirement is provided. In other words, a type of piston is arranged in the air duct, which piston is positioned as a function of air pressures acting on the piston and as a function of the spring force of the spring element connected to the piston, wherein the differential pressure and / or the maintenance requirement can be read directly by the position and the marking. This provides an analog display unit which is simple and cost-effective and does not require an electrical connection and an electronic evaluation unit. The first air connection is in particular fluidically connected to a connecting piece of the air intake duct arranged downstream of the air filter. The second air connection can likewise be fluidically connected to a connecting piece of the air intake duct, which connecting piece is arranged in front of the air filter. Alternatively, the second air connection can be fluidically connected to the external environment, i.e. not to the air intake duct, wherein the ambient pressure substantially corresponds to the air pressure upstream of the air filter.An exemplary embodiment of the invention is explained in more detail with reference to the drawings. FIG. 1 schematically shows an air filter test arrangement, and FIG. 2 schematically shows a further embodiment of a test device for an air filter test arrangement from FIG. 1.FIG. 1 shows an internal combustion engine 10, an associated air intake system 20 and an associated exhaust gas manifold 30. the internal combustion engine 10 has a plurality of cylinders 12, in which a combustion process takes place and in which a piston in each case moves. For carrying out the combustion processes, the internal combustion engine 10 has a plurality of fuel injectors, not shown, in FIG. 1, by means of which fuel can be injected into the cylinders 12 as required. In addition, the combustion process requires air which is guided through an air intake duct 22 of the air intake system 20 to the cylinders 12 and is introduced into the cylinders 12 as required via inlet valves, not shown in FIG. 1. After the combustion process, the exhaust gases produced in this case are discharged into the external environment via the exhaust system 30. The exhaust system 30 has a plurality of exhaust gas aftertreatment components 44 for pollutant reduction, in particular a catalytic converter and a particle filter, wherein only one of the exhaust gas aftertreatment components 44 is shown in FIG. 1.The air supplied to the cylinders 12 via the air intake duct 20 has a charge pressure which has been compressed by an exhaust gas turbocharger 32. Exhaust gas turbocharger 32 has a turbine wheel 321 situated in an exhaust gas duct of exhaust system 30, and a compressor wheel 322 situated in air intake duct 22. In operation of the internal combustion engine 10, the exhaust gases flow around the turbine wheel 321, thereby driving the turbine wheel 321. By having the compressor wheel 322 rotationally fixed to the turbine wheel 321, the compressor wheel 322 rotates together with the turbine wheel 321, thereby drawing in air from the outside environment and compressing it before flowing into the cylinders 12.In order to prevent dirt particles from flowing into the cylinders 12, an air filter 40 is arranged at an air inlet region of the air intake duct 22. During operation of the internal combustion engine 10, the air flowing through the air intake duct 22 initially flows through the air filter, as a result of which the dirt particles entrained by the air are filtered out. The air then flows through the exhaust gas turbocharger 30 and then flows into the cylinders 12.It is problematic that the air throughput through the air filter 40 can be reduced by the contamination of the air filter 40 in such a way that sufficient air cannot flow into the cylinders 12 for the operation of the internal combustion engine 10, which can result in an increased pollutant emission by the exhaust gases and possibly an engine damage. Otherwise, the air filter 40 is usually replaced or cleaned at regular maintenance intervals of the motor vehicle, regardless of whether the replacement or cleaning is required.In order to avoid the unnecessary replacement of the air filter 40 and in particular an operation of the internal combustion engine 10 with a strongly clogged air filter 40, a testing device 52 is arranged at a connection point 24 of the air intake unit 20 at which a connection piece 25 is provided. The test device 52 forms together with the air intake duct 22 an air filter test arrangement 50.The test device 52 can either be permanently fastened to the connector 25 or can be mounted on the connector 24 only when necessary, for example during a maintenance interval, wherein the connector 25 is closed, for example by a plug, when the test device 52 is removed. The test device permanently arranged on the connecting piece 25 necessarily has a display element 53.In a first embodiment shown in FIG. 1, the test device 52 is designed in the form of a differential pressure sensor with a digital display unit 53 which can be mounted on the connection point 24 as required or is permanently mounted on the connection point 24 in order to determine the differential pressure between the air pressures in the flow direction of an air flowing from the external environment to the internal combustion engine 10 before and after the air filter 40. In particular, the test device 52 is designed to fluidically connect to the air intake duct 22 at the connection point 24 and to determine the differential pressure between the ambient pressure and the air pressure downstream of the air filter 40 in the flow direction of the air flowing through the air intake duct 22. The differential pressure determined is displayed via the digital display unit 53, from which a person can conclude whether the air filter 40 has to be serviced or replaced. Alternatively, a maintenance requirement, which is determined based on the determined differential pressure, can be displayed directly via the digital display unit 53.In a second embodiment shown in FIG. 2, the test device 52 has a housing 54 with a first air connection 56 and a second air connection 58, wherein the air connections 56, 58 are connected to one another via an air duct 60. In this embodiment, the test device 52 can be permanently mounted on the connection point 24 or can be mounted on the connection point 24 as required. A translationally movable, spring-biased element 62 in the form of a piston is arranged in the air duct 60, wherein the air duct 60 is separated by the element 62 into a region 601 which is fluidically connected to the first air connection 56 and a region 602 which is fluidically connected to the second air connection 58. The first air connection 56 is fluidically connected to the air intake duct 22 via the connection piece 25. The second air connection 58 is fluidically connected to the external environment. A marking 66 is provided on an outer side of the housing 54 visible to a worker, wherein the housing 54 is transparent, for example by a pane 64, in the region of the marking 66. As a result, an analog display unit 55 is provided in a very simple manner.During an inspection of the motor vehicle, the factory can open the engine hood, for example, and, with a permanently mounted test device according to FIG. 2 and the internal combustion engine 10 running, sees immediately whether the air filter has to be serviced or replaced. Alternatively, in the case of a test device which is not permanently mounted on the air intake system 20, the worker can remove a plug from the connecting piece 25 and mount the test device 52 on the connecting piece 25. Subsequently, when the internal combustion engine 10 is running, the worker can see via the display unit 53, 55 whether the air filter 40 has to be serviced or changed.

Claims

Air filter test arrangement having an air intake duct (22) of an air intake system (20) of an internal combustion engine (10), an air filter (40) which is arranged in the air intake duct (22), and a test device (52) which, in the event of maintenance, can be temporarily mounted on at least one fluidic connection point (24) of the air intake duct (22) and can be fluidically connected to the air intake duct (22), wherein the connection point (24) is arranged behind the air filter (40) in the flow direction of the air flowing through the air intake duct (22), and wherein the test device (52) is designed to determine a differential pressure between the two air pressures in the flow direction upstream of the air filter (40) and downstream of the air filter (40), wherein the test device (52) is designed to display the determined differential pressure and / or a maintenance requirement of the air filter (40) determined on the basis of the determined differential pressure, wherein the test device (52) has a differential pressure sensor with a digital display unit (53).Air filter test arrangement having an air intake duct (22) of an air intake system (20) of an internal combustion engine (10), an air filter (40) which is arranged in the air intake duct (22), and a test device (52) which is permanently mounted on a fluidic connection point (24) of the air intake duct (22) and is fluidically connected to the air intake duct (22), wherein the fluidic connection point (24) is arranged behind the air filter (40) in the flow direction of the air flowing through the air intake duct (22), and wherein the test device has a display unit (55) and is designed to determine a differential pressure between the two air pressures in the flow direction upstream of the air filter (40) and downstream of the air filter (40) and to display the differential pressure and / or a maintenance requirement of the air filter (40) determined on the basis of the determined differential pressure, wherein the test device (52) has a differential pressure sensor with a digital display unit (53).Method for operating the air filter test arrangement according to Claim 1, having the following steps: - temporary mounting of the test device (52) on the fluidic connection point (24) of the air intake duct (22), - operating the internal combustion engine (10) in such a way that air flows via the air intake duct (22) via the air filter (40) to the internal combustion engine (40), - determination of the differential pressure by the test device (52) temporarily mounted on the fluidic connection point (24).Method for operating the air filter test arrangement according to Claim 2, having the following steps: - operating the internal combustion engine (10) in such a way that air flows via the air intake duct (22) via the air filter (40) to the internal combustion engine (10), - determining the differential pressure by the test device (52) mounted on the fluidic connection point (24), and - displaying the determined differential pressure and / or the maintenance requirement of the air filter (40).

Images