Arrangement for measuring a differential pressure

Abstract

Arrangement for measuring a differential pressure across a particulate filter assembly (1) with a particulate filter (20) within a pipe (12) arranged in a flow path (2) of exhaust gases from an internal combustion engine (3), the arrangement comprising: • a first conduit (5) connected at one end of the assembly to the flow path at an inlet (6) therefrom to the particulate filter assembly, • a second conduit (7) connected at one end of the assembly to the flow path at an outlet (8) therefrom to the particulate filter assembly, and • a pressure sensor (9) to which the pipes (5, 7) are connected and which is configured to measure a difference in the pressures in the flow path at the inlet and the outlet, wherein the pressure sensor (9) is configured to be arranged at a location along the particulate filter assembly (1), wherein both pipes are configured to protrude from the particulate filter assembly at this point, wherein the arrangement comprises at least one channel (11) opening into the flow path at one end of the particle filter assembly and extending on the outside of the tube (12) of the particle filter assembly to one of the pipes projecting from the particle filter assembly at a distance from said one end, while the channel is enclosed between the tube and a heat-insulating element (13) outside thereof, and wherein the channel (11) has an elongated cross-section with a width which has an arcuate extension in the circumferential direction with respect to the tube (12) of the particulate filter assembly and exceeds its height which extends radially with respect to a central axis of the tube of the particulate filter assembly.

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to an arrangement for measuring a differential pressure across a particulate filter assembly having a particulate filter within a pipe arranged in a flow path of exhaust gases from an internal combustion engine, the arrangement comprising a first pipe connected at one end of the arrangement to the flow path at an inlet therefrom to the particulate filter assembly, a second pipe connected at one end of the arrangement to the flow path at an outlet therefrom to the particulate filter assembly, and a pressure sensor to which the pipes are connected and which is configured to measure a difference in the pressures in the flow path at the inlet and the outlet.

[0002] The invention relates to such arrangements for measuring a differential pressure across a particulate filter assembly arranged in a flow path of exhaust gases from an internal combustion engine for any purpose, such as industrial applications in grinding machines and motor vehicles of all kinds, although the invention is particularly applicable to motor vehicles and preferably to wheeled commercial vehicles, such as lorries or trucks and buses. This is the reason why the invention is discussed primarily for this specific application, without being limited thereto. The reason for an arrangement for measuring a differential pressure across a particulate filter assembly is that after a certain period of operation of the internal combustion engine, the particulate filter assembly is so filled with particles that it must be regenerated by raising the temperature of the exhaust gases and burning the particles collected in the particulate filter assembly.The value of the mentioned differential pressure indicates when such regeneration must take place.

[0003] Depending on the length of the particulate filter assembly, the connections of the first and second pipes along the flow path may be too far apart to allow for proper drainage of the condensate, which can eventually cause the water to freeze and impede the function of the pressure sensor. This problem arises when the internal combustion engine is used in locations where low temperatures may prevail, particularly when the internal combustion engine is installed in a motor vehicle used in regions where cold climates may occur. BACKGROUND

[0004] EP 1 598 533 A2 discloses an arrangement according to the introduction, which has long pipes leading to a pressure sensor, which is subject to an inherent risk of clogging due to freezing water when the internal combustion engine is used with a particulate filter assembly in a cold environment. Therefore, the aim should be to achieve a compact installation of the differential pressure sensor and the particulate filter assembly to be monitored. However, if the particulate filter assembly is long, the pipes tend to have a slight gradient to keep the installation compact, which negatively impacts the condensate drainage behavior of the pipes.

[0005] DE 10 2015 226 573 A1 describes an exhaust gas purification system that prevents the airstream from directly impacting the differential pressure pipes and the water content in the differential pressure pipes from freezing.The exhaust gas purification system comprises a nearly cylindrical housing accommodating a DPF, a differential pressure sensor detecting a differential pressure of the DPF upstream and downstream, and a downstream differential pressure pipe connecting an exhaust passage near the DPF to the differential pressure sensor. The housing is divided along its outer side into halves welded together by extension pieces to form a unit. The downstream differential pressure pipe is arranged along the outer side of the housing and has a bend and an outer part which are exposed and are arranged on the outer side of the housing facing the rear of the vehicle and further towards the rear of the vehicle than the closer extension piece.

[0006] DE 103 24 165 A1 describes a particle filter system of a diesel engine-powered motor vehicle with at least one particle filter element which is accommodated in a filter housing which is introduced into the exhaust system of the motor vehicle via an exhaust gas inlet and an exhaust gas outlet, wherein means for regenerating the particle filter element are provided and the filter housing has a closed inner housing part containing the particle filter element, on which an outer housing part which at least partially surrounds the inner housing part in a shell-like manner is arranged in such a way that a pressure-tight air gap for thermal insulation remains between the inner housing part and the outer housing part. OVERVIEW OF THE INVENTION

[0007] The object of the present invention is to provide an arrangement of the type defined in the introduction which addresses the problems disclosed above.

[0008] This object is achieved according to the invention by providing such an arrangement with the features listed in the characterising part of the appended claim 1.

[0009] Thus, the pressure sensor is configured to be arranged at a location along the particulate filter assembly, wherein both pipes are configured to protrude from the particulate filter assembly at that location, and wherein the arrangement comprises at least one channel which opens into the flow path at one end of the particulate filter assembly and extends on the outside of the pipe of the particulate filter assembly to one of the pipes which protrude from the particulate filter assembly at a distance from that one end, while the channel is enclosed between the pipe and a heat-insulating element outside thereof.By having both pipes protrude from the particulate filter assembly at the same location, and at least one of them reaching the flow path upstream or downstream of the particulate filter assembly through such a channel, a compact installation of the particulate filter assembly and the pressure sensor is achieved, while at the same time allowing the use of short pipes to reach the pressure sensor. Such short pipes mean that condensate is less likely to freeze compared to longer pipes. A further significance is that such short pipes can be installed at a steeper slope than longer pipes, such as almost vertically if desired, resulting in good condensate drainage through the use of gravity.In addition, by arranging the duct on the outside of the hot exhaust gas pipe of the particulate filter assembly, enclosed between this pipe and a heat-insulating element outside it, this duct is kept warm and protected from the condensate water contained therein freezing.

[0010] According to one embodiment of the invention, the pressure sensor is configured to be located at a first of said ends of the particulate filter assembly, and the channel opens into said flow path at a second end of the particulate filter assembly opposite the first end, and this channel extends on the outside of the tube of the particulate filter assembly toward the first end to one of the conduits, while being enclosed outside thereof between the conduit and the heat-insulating element. Because the pressure sensor is located at one end of the particulate filter assembly and the two conduits protrude from the particulate filter assembly at this end, only a single said channel is required to achieve the object sought by the invention, which simplifies the design of the assembly.

[0011] According to a further embodiment of the invention, the pressure sensor is configured to be arranged at the inlet to the particulate filter assembly, and the channel extends from the outlet of the particulate filter assembly to the second conduit. This results in an advantageous arrangement of the differential pressure sensor.

[0012] According to a further embodiment of the invention, the pipes are configured such that they protrude from the particulate filter assembly in a direction that, when the particulate filter assembly is in its normal position, forms an angle of > 30° with a horizontal plane. Such a direction of extension of the pipes offers good opportunities for efficiently draining the condensate contained in the pipes. "Normal position" here refers to the position a particulate filter assembly arranged in a motor vehicle assumes when the vehicle is on a horizontal ground.

[0013] According to a further embodiment of the invention, the pipes are configured to protrude from the particulate filter assembly in a direction that, when the particulate filter assembly is in its normal position, forms an angle of 85°-95°, of substantially 90°, or of 90°, with a horizontal plane. Such an extension direction of the pipes is advantageous for the reasons just mentioned, and this is particularly the case when combined with another embodiment of the invention in which the pipes are configured to be arranged to protrude upward from the pipe of the particulate filter assembly, while forming the angle with a horizontal plane when the particulate filter assembly is in its normal position.In the case of an arrangement used in a motor vehicle, such a normal position is defined as the position assumed when the vehicle is on horizontal ground.

[0014] According to a further embodiment of the invention, the pipes are configured such that they protrude from the particulate filter assembly substantially parallel to one another or parallel to one another.

[0015] The channel has an elongated cross-section with a width that has an arcuate extension in the circumferential direction with respect to the tube of the particulate filter assembly and exceeds its height, which extends radially with respect to a central axis of the tube of the particulate filter assembly. Such a wide channel means that, if necessary, an increased amount of water can be contained within it before being drained or evaporated.

[0016] According to a further embodiment of the invention, the arrangement is configured to measure a differential pressure across a particulate filter assembly arranged in a flow path of exhaust gases from an internal combustion engine of a motor vehicle, which represents a particularly preferred use of an arrangement according to the present invention, in particular when the motor vehicle is to be used in a cold environment.

[0017] The invention also relates to the use of an arrangement for measuring a differential pressure across a particulate filter assembly in a motor vehicle, a vehicle particulate filter assembly and a motor vehicle provided with such an arrangement according to the appended claims directed thereto.

[0018] Further advantageous features and advantages of the present invention will become apparent from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] With reference to the accompanying drawings, a specific description of embodiments of the invention given as examples follows.

[0020] In the drawings: Fig. Figure 1 shows very schematically an internal combustion engine with an exhaust system provided with a particulate filter assembly on which an arrangement for measuring the differential pressure across this particulate filter assembly is to be arranged, Fig. Figure 2 is a partially sectional view of a part of a particulate filter assembly provided with an arrangement according to a first embodiment of the invention, and Fig. 3 is a cross-sectional view of the Fig. 2 shown embodiment at III-III, wherein the Fig. 2 symbolized pressure sensor is omitted, and Fig. 4 is a similar view to that of Fig. 2, which shows an arrangement according to a second embodiment of the invention. DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0021] Fig. Figure 1 is a highly simplified view showing how an arrangement for measuring differential pressure across a particulate filter assembly 1 having a particulate filter 20 may be arranged within a pipe arranged in a flow path 2 of exhaust gases from an internal combustion engine 3 in a motor vehicle 4. This arrangement comprises a first pipe 5 connected to the flow path at an inlet 6 thereof to the particulate filter assembly, a second pipe 7 connected to the flow path at an outlet 8 thereof from the particulate filter assembly, and a pressure sensor 9 to which the pipes 5, 7 are connected and which is configured to measure a difference in pressures in the flow path at the inlet 6 and the outlet 8.

[0022] The Fig. 2 and Fig. 3 show the structure of an arrangement of the Fig. 1 according to a first embodiment of the invention, in which the pressure sensor 9 is arranged at a location at a first end 10 of the particulate filter assembly, specifically at its inlet 6. The first conduit 5 and the second conduit 7 are short conduits, but may also be considerably longer than shown, for example twice as long, the conduits extending vertically from the particulate filter assembly to the pressure sensor, and accordingly both being arranged at the first end 10 of the particulate filter assembly. A channel 11 opens into the flow path at the outlet 8 from the particulate filter assembly at its second end 14 and extends on the outside of the tube of the particulate filter assembly to the second conduit 7, while being enclosed between the tube 12 of the particulate filter assembly and a heat-insulating element 13 outside thereof.This duct 11 has an elongated cross-section with a width that has an arcuate extension in the circumferential direction with respect to the pipe of the particulate filter assembly and exceeds its height, which extends radially with respect to the central axis of the pipe 12 of the particulate filter assembly. The pressure difference at the inlet 6 and the outlet 8 of the particulate filter assembly can thus be determined by connecting the two pipes 5, 7 to the pressure sensor 9. The limited length of these pipes and their vertical extension result in good drainage of condensate and a very low risk of this water freezing therein. Any condensate inside the duct is efficiently evaporated by the high temperatures prevailing there, as it is enclosed between the particulate filter assembly, which conducts the hot exhaust gases, and the heat-insulating element.Condensation water forming in the pipes is drained away or evaporated before freezing thanks to the slowly decreasing temperature of the porous medium 20 within the particulate filter assembly after the combustion engine is switched off.

[0023] Fig. Figure 4 shows the application of an arrangement according to a second embodiment of the invention to a particle filter assembly, this arrangement being different from that shown in Fig. 2 only in that the two pipes and the pressure sensor are located at the second end 14 of the particulate filter assembly, leading to a channel 11 connecting the first pipe 5 to the inlet 6 of the flow path to the particulate filter assembly.

[0024] The invention is of course in no way limited to the embodiments described above, since many possibilities for modification thereof will be obvious to a person skilled in the art without having to depart from the subject matter of the invention as defined in the appended claims.

Claims

[1] An arrangement for measuring a differential pressure across a particulate filter assembly (1) having a particulate filter (20) within a pipe (12) arranged in a flow path (2) of exhaust gases from an internal combustion engine (3), the arrangement comprising: • a first conduit (5) connected at one end of the assembly to the flow path at an inlet (6) therefrom to the particulate filter assembly, • a second conduit (7) connected at one end of the assembly to the flow path at an outlet (8) therefrom to the particulate filter assembly, and • a pressure sensor (9) to which the pipes (5, 7) are connected and which is configured to measure a difference in the pressures in the flow path at the inlet and the outlet, wherein the pressure sensor (9) is configured to be arranged at a location along the particulate filter assembly (1), wherein both pipes are configured to protrude from the particulate filter assembly at this point, wherein the arrangement comprises at least one channel (11) opening into the flow path at one end of the particle filter assembly and extending on the outside of the tube (12) of the particle filter assembly to one of the pipes projecting from the particle filter assembly at a distance from said one end, while the channel is enclosed between the tube and a heat-insulating element (13) outside thereof, and wherein the channel (11) has an elongated cross-section with a width which has an arcuate extension in the circumferential direction with respect to the tube (12) of the particulate filter assembly and exceeds its height which extends radially with respect to a central axis of the tube of the particulate filter assembly. [2] Arrangement according to claim 1, characterized byin that the pressure sensor (9) is configured to be arranged at the location at a first (10) of the ends of the particulate filter assembly, and in that the channel (11) opens into the flow path at a second end (14) of the particulate filter assembly, which is opposite to the first end, and this channel extends on the outside of the tube (12) of the particulate filter assembly towards the first end to one of the tubes, while being enclosed between the tube and the heat-insulating element (13) outside thereof. [3] Arrangement according to claim 2, characterized by that the pressure sensor (9) is configured to be arranged at the inlet (6) to the particulate filter assembly, and that the channel (11) extends from the outlet (8) of the particulate filter assembly to the second conduit (7). [4] Arrangement according to one of the preceding claims, characterized byin that the pipes (5, 7) are configured such that they protrude from the particle filter assembly in a direction which, in a state of a normal position assumed by the particle filter assembly, forms an angle > 30° with a horizontal plane. [5] Arrangement according to claim 4, characterized by in that the pipes (5, 7) are configured such that they protrude from the particulate filter assembly in a direction which, in a state of a normal position assumed by the particulate filter assembly, forms an angle of 85°-95°, of substantially 90° or of 90°, with a horizontal plane. [6] Arrangement according to claim 4 or 5, characterized byin that the pipes (5, 7) are configured to be arranged such that they protrude upwards from the pipe (12) of the particulate filter assembly while forming the angle with a horizontal plane in a state of a normal position assumed by the particulate filter assembly. [7] Arrangement according to one of the preceding claims, characterized by that the pipes (5, 7) are configured such that they protrude from the particle filter assembly substantially parallel to one another or parallel to one another. [8] Arrangement according to one of the preceding claims, characterized by in that it is configured to measure a differential pressure across a particle filter assembly (1) arranged in a flow path (2) of exhaust gases from an internal combustion engine (3) within a motor vehicle (4). [9] Use of an arrangement according to one of the preceding claims for measuring a differential pressure across a particle filter assembly (1) in a flow path (2) of exhaust gases of an internal combustion engine (3) in a motor vehicle (4). [10] Vehicle particulate filter assembly, characterized by that it is provided with an arrangement according to any one of claims 1-8. [11] Motor vehicle, in particular a heavy motor vehicle with wheels, such as a lorry or a bus, characterized by that it is provided with a particulate filter assembly comprising an arrangement according to any one of claims 1 to 8.

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