CONNECTING DEVICE FOR AN EXHAUST GAS MEASURING SYSTEM

Description

[0001] The invention relates to a connecting device for connecting an exhaust gas probe to an exhaust gas measuring device and to an exhaust gas measuring system with such a connecting device. State of the art

[0002] Testing and diagnostic procedures for internal combustion engines installed in vehicles often use measured variables that characterise the gas concentration of the emitted combustion gases.

[0003] In order to determine these measured values, exhaust gases are taken from the exhaust of the combustion engine using an exhaust gas probe and fed to an exhaust gas measuring device.

[0004] Particularly in vehicles with diesel engines, the exhaust gases contain not only gaseous components such as HC, CO, CO 2 , O 2 , NO x but also a relevant amount of solid components (particles), in particular soot particles, which lead to severe contamination of the measuring chamber of the exhaust gas measuring device.

[0005] Contamination of the measuring chamber results in incorrect measurement results and may make it necessary to replace the measuring cell installed in the measuring chamber.

[0006] Therefore, when measuring gases containing particles, such as those found in diesel engines in particular, special protective measures are required for the gas supply to the exhaust gas measuring device.

[0007] A gas supply system therefore usually includes several filter units that are attached to the measuring device.

[0008] EP 2 428 263 A1 discloses an exhaust gas measuring device comprising a filter hose system. The filter hose system has a filter equipped with a connection section and filter coupling sockets with two sets of openings for holding the connection section and a hose connection, respectively. Further measuring devices are known from US Pat. Nos. 5,490,868 A and 6,308,130 B1. Disclosure of the invention:

[0009] It is an object of the invention to provide an improved exhaust gas supply from an exhaust gas probe to an exhaust gas measuring device, in particular for supplying exhaust gases from a diesel engine. This is achieved by a connecting device according to claim 1 and a use according to claim 12.

[0010] According to the invention, a connecting device for connecting an exhaust gas probe to an exhaust gas measuring device comprises at least one high-efficiency particulate matter filter (HEPA fine filter) which is designed to filter out particles from an exhaust gas stream flowing through the connecting device from the exhaust gas probe to the exhaust gas measuring device.

[0011] Embodiments of the invention also include an exhaust gas measuring system comprising an exhaust gas measuring device, an exhaust gas probe and a connecting device according to the invention, wherein the connecting device connects the exhaust gas probe to the exhaust gas measuring device to enable exhaust gas flow from the exhaust gas probe to the exhaust gas measuring device.

[0012] The exhaust gas measuring device can be designed, in particular, for measuring exhaust gases from a gasoline engine. A connecting device according to the invention efficiently filters out the particles contained in the exhaust gases of an internal combustion engine, in particular a diesel engine. Therefore, an exhaust gas measuring device originally designed for measuring exhaust gases from a gasoline engine can also be used to measure exhaust gases from a diesel engine.

[0013] A HEPA fine filter removes even very small particles from the exhaust stream, preventing them from contaminating the exhaust gas analyzer. A HEPA filter is highly efficient and has a long service life. Therefore, the filter rarely needs to be replaced, reducing maintenance costs.

[0014] The integration of a filter element containing a HEPA fine filter ("HEPA fine filter element") into the connection device simplifies its handling. Furthermore, the stability of the connection device is improved and its service life is increased.

[0015] In one embodiment, the connecting device comprises three connecting segments, and the filter element is arranged between two connecting segments. This allows a filter element to be integrated into the connecting device in a simple and easily replaceable manner.

[0016] In one embodiment, the filter element has at least one extension piece, and at least one connecting segment of the connecting device is pushed onto the at least one extension piece. In this way, a filter element can be easily integrated into the connecting device such that the interface between the filter element and the connecting segment is gas-tight and mechanically stable, and the filter element can be easily replaced. The at least one extension piece can, in particular, be tubular.

[0017] In one embodiment, the filter element is designed as a so-called "in-line filter element." This means that the diameters of the attachments at the inlet and outlet of the filter element are selected so that the filter element can be inserted directly into one of the connecting segments of the connecting device. In particular, no screwed connections to the adjacent connecting segments are required. This significantly simplifies the installation and replacement of the filter elements.

[0018] In one embodiment, the connecting segment is designed as a hose segment, in particular as an elastic and movable hose segment. The hose segment can in particular be made of a material containing an elastomer, in particular a fluoroelastomer, for example VITON®.

[0019] Due to its flexibility, an elastic hose segment enables easy handling of the connecting device and a reliably gas-tight connection between the connecting segment and the filter element.

[0020] In one embodiment, at least one coarse filter element is additionally integrated into the connecting device. The at least one coarse filter element is arranged, in particular, upstream of the at least one HEPA fine filter element in the flow direction of the exhaust gases.

[0021] A coarse filter element arranged in front of the HEPA fine filter element in the flow direction of the exhaust gases prevents the HEPA fine filter element from becoming quickly contaminated and blocked by coarse particles.

[0022] The coarse filter element can be formed with a cost-effective paper filter.

[0023] The size of the fine filter element is chosen so that it is as small as possible and its dimensions correspond in particular to the dimensions of the coarse filter element.

[0024] In one embodiment, the length of the connecting segments of the connecting device is selected so that the HEPA fine filter element does not lie on the floor during practical operation and is thus well protected from damage.

[0025] In one embodiment, the connecting device comprises a coarse filter element, a first HEPA fine filter element, a longer connecting segment, and a second HEPA fine filter element in the direction of the exhaust gas flow. The first HEPA fine filter element, which is arranged upstream of the longer connecting segment in the direction of the exhaust gas flow, keeps the longer connecting segment largely free of particle deposits. This increases the service life of the longer connecting segment. The longer connecting segment can, in particular, have a length of several meters to allow convenient installation of the exhaust gas probe in and / or on the exhaust of an internal combustion engine.

[0026] In one embodiment, the filter efficiency of the HEPA fine filter is at least 99.9%. The effective filter diameter of the HEPA fine filter is selected in particular so that the HEPA fine filter filters out particles larger than 100 nm.

[0027] In one embodiment, the filters are designed for a maximum pressure difference of 10 mbar.

[0028] In one embodiment, the housing of the at least one filter element is made of a corrosion-resistant material, in particular a plastic material. In particular, all components of the exhaust gas measurement system that come into contact with the exhaust gases to be measured are free of metallic materials to prevent corrosion.

[0029] In one embodiment, the filter elements and filters are made of a material, e.g., a borosilicate microfiber with a Kynar (PCDF) binder, that prevents the accumulation and subsequent outward diffusion of gases to be measured, in particular HC, CO, CO 2 , O 2 , NO x . This prevents falsification of the measurement results due to the accumulation and subsequent outward diffusion of gaseous components of the exhaust gases to be measured.

[0030] In one embodiment, the housing of the filter element is at least partially transparent, so that contamination of the filter is visible from the outside.

[0031] In one embodiment, an at least partially transparent (fine) filter element is arranged directly upstream of the inlet of the exhaust gas measuring device. By visually monitoring the filter in the at least partially transparent filter element, conclusions can be drawn about the entire connection device. In particular, increasing contamination of the filter, which can be detected through the at least partially transparent housing, indicates that filters arranged upstream of the filter element in the flow direction are defective and / or exhausted.

[0032] In one embodiment, the at least one filter element has a gas-tight housing and is designed so that the exhaust gases flow through the filter from its outer side to its inner side. The particles trapped in the filter form a dark deposit on the filter, which is clearly visible from the outside. A visual inspection of the filter element therefore makes it easy to determine how dirty the filter is and whether it needs to be replaced.

[0033] In one embodiment, the at least one filter element comprises a filter that has a defined pressure difference depending on the flow velocity, whereby the pressure difference does not exceed an upper limit. The use of such a filter with a defined pressure difference leads to defined pressure and flow conditions in the connecting device, thereby improving the quality and reliability of the measurement results. Short description of the characters

[0034] An embodiment of the invention is described below with reference to the accompanying figures. Figure 1 shows a schematic view of an exhaust gas measuring system according to an embodiment of the invention. Figure 2 shows a schematic sectional view of a filter element as used in a connecting device according to an embodiment of the invention. Character description

[0035] Figure 1 shows a schematic view of an exhaust gas measuring system 2 according to an embodiment of the invention.

[0036] The exhaust gas measuring system 2 comprises an exhaust gas measuring device 6, an exhaust gas probe 4 which is designed to be arranged in or on an exhaust of a vehicle (not shown) with an internal combustion engine, and a connecting device 8 which connects the exhaust gas probe 4 to the exhaust gas measuring device 6 so that exhaust gases can flow from the exhaust gas probe 4 into the exhaust gas measuring device 6.

[0037] The connecting device 8 comprises a plurality of connecting segments 9a, 9b, 9c and filter elements 10, 12, each of which is arranged between two of the connecting segments 9a, 9b, 9c.

[0038] A first connecting segment 9a connects an outlet of the exhaust gas probe 4 with an inlet of a first filter element 10.

[0039] A second connecting segment 9b connects an output of the first filter element 10 to an input of a second filter element 12.

[0040] A third connecting segment 9c connects an output of the second filter element 12 with an input of the exhaust gas measuring device 6.

[0041] The second connecting segment 9b is typically the longest of the three connecting segments 9a, 9b, 9c. It can, in particular, have a length of several meters to allow convenient installation of the exhaust gas probe 4 in and / or on the exhaust of the internal combustion engine.

[0042] The first and third connecting segments 9a, 9c, however, can be significantly shorter and in particular have lengths of less than 1 m, e.g. lengths between 0.25 and 0.5 m.

[0043] The first filter element 10 is designed, in particular, as a coarse filter element 10 with a coarse filter to remove coarse particles from the exhaust gas stream. The coarse filter can, in particular, be designed as a cost-effective paper filter.

[0044] The second filter element 12 is designed in particular as a fine filter element 12 with a highly efficient particulate matter filter (HEPA fine filter) in order to filter out fine particles, in particular all particles having a diameter larger than 100 nm, from the exhaust gas stream.

[0045] The person skilled in the art will understand that the connecting device 8 may contain further filter elements 10, 12, in particular additional HEPA fine filter elements 12 and connecting segments 9a, 9b, 9c, in order to further increase the filtering effect of the connecting device 8. In particular, a third (not shown) filter element 10 may be arranged between the second filter element 12 and the exhaust gas measuring device 6. Figure 1 shown) filter element containing a second HEPA fine filter.

[0046] Figure 2shows a sectional view of a filter element 10, 12 according to an embodiment of the invention. This can be a first filter element (coarse filter element) 10 or a second filter element (fine filter element) 12. The first filter element 10 and the second filter element 12 of a connecting device 8 can have the same or different dimensions.

[0047] The filter element 10, 12 has a first, inlet-side attachment piece 14 and a second, outlet-side attachment piece 16.

[0048] The extension pieces 14, 16 are tubular, so that connecting segments 9a, 9b, 9c, in particular tubular connecting segments 9a, 9b, 9c, can be pushed onto the extension pieces 14, 16.

[0049] A cylindrical housing 18 is arranged between the coaxially formed extension pieces 14, 16. The axis of the cylindrical housing 18 is coaxial with the axes of the two tubular extension pieces 14, 16.

[0050] The housing can, for example, have a diameter D of 20 mm to 30 mm, in particular a diameter D of 25 mm, and a length L of 40 mm to 50 mm, in particular a length L of 45 mm. The extension pieces 14, 16 can each have a diameter d of 5 mm to 7 mm, in particular a diameter d of 6 mm, and a length I of approximately 20 mm.

[0051] A filter 20 is located in the housing 18. The filter 20 can be a coarse or fine filter, which is designed as a paper filter or as a HEPA filter.

[0052] The outer diameter of the extension pieces 14, 16 and the inner diameter of the connecting segments 9a, 9b, 9c (see Figure 1) are selected so that the connecting segments 9a, 9b, 9c sit tightly on the extension pieces 14, 16 and in particular a gas-tight connection between the connecting segments 9a, 9b, 9c and the extension pieces 14, 16 is ensured.

[0053] In this way, a stable and reliable gas-tight connection is created between the connecting segments 9a, 9b, 9c and the extension pieces 14, 16 without the need for tools and / or additional fastening elements.

[0054] The housings of the filter elements 10, 12 are gas-tight and in particular at least partially transparent, so that contamination of the filter 20 arranged in the respective filter element 10, 12 can be recognized from the outside.

[0055] The filter elements 10, 12 are designed in particular so that exhaust gases entering the filter element 10, 12 through the inlet-side attachment piece 14 flow from the outside to the inside through the filter 20.

[0056] Particles trapped in the filter 20 form a dark deposit that is visible from the outside through the at least partially transparent housing 18. By visually inspecting the filter element 10, 12, it is therefore easy to determine how heavily the filter 20 is contaminated and whether the filter 20 needs to be replaced.

[0057] A filter element 10, 12 with a transparent housing can be arranged, in particular, directly upstream of the exhaust gas measuring device 6. By visually inspecting a filter 20 arranged directly upstream of the exhaust gas measuring device 6, the condition of the entire connecting device 8 can be checked. Visible contamination of a filter 20 arranged directly upstream of the exhaust gas measuring device 6 indicates that the upstream filter elements 10, 12 are defective or worn out and should be checked and, if necessary, replaced.

[0058] The filter elements 10, 12, the filters 20 and the connecting segments 9a, 9b, 9c are preferably made of a metal-free material in order to avoid corrosion by the exhaust gases.

[0059] The filter elements 10, 12, the filters 20, and the connecting segments 9a, 9b, 9c are made, in particular, of a material that prevents the accumulation and subsequent outward diffusion of gases to be measured, in particular HC, CO, CO2, O2, and NOx. This prevents falsification of the measurement results due to the accumulation and subsequent outward diffusion of gaseous components of the exhaust gases to be measured.

[0060] To achieve this, the filters 20 can be made, for example, from a borosilicate microfiber with a Kynar (PCDF) binder

[0061] The filter 20 can, in particular, be designed to have a defined pressure difference that depends on the flow velocity and does not exceed a predetermined upper limit. The use of such a filter 20 results in defined pressure and flow conditions in the connecting device 8. This prevents the measurement results from being distorted by pressure and / or flow fluctuations in the connecting device 8. The quality and reliability of the measurement results are thus improved.

[0062] By selecting special filters 10, 12 and arranging them in the connecting device 8 between the exhaust gas probe 4 and the exhaust gas measuring device 6, many disadvantages of conventional exhaust gas measuring systems are avoided.

[0063] For example, the costs of the exhaust gas measuring system 2 can be significantly reduced and its maintenance intervals can be extended.

[0064] An exhaust gas measuring system 2 for measuring gas concentrations in a particle-laden exhaust gas stream according to embodiments of the invention can be used in particular in workshops.

[0065] An exhaust gas measurement system 2 according to embodiments of the invention enables gas measurements that fully comply with the requirements of international standards, such as OIML R 99. The exhaust gas measurement system 2 can therefore also be used in official inspections, for example, as part of the periodic vehicle inspection.

Claims

1. Connecting device (8) for connecting an exhaust-gas probe (4) to an exhaust-gas measuring apparatus (6) in order to allow an exhaust-gas flow from the exhaust-gas probe (4) to the exhaust-gas measuring apparatus (6), wherein the connecting device (8) comprises at least one filter element (10, 12) integrated into the connecting device (8), wherein at least one filter element (12) integrated into the connecting device (8) contains a HEPA fine filter (20), characterized in that the connecting device (8) comprises a plurality of connecting segments (9a, 9b, 9c) and filter elements (10, 12), wherein the filter elements (10, 12) are each arranged between two of the connecting segments (9a, 9b, 9c), wherein a second connecting segment (9b) connects an output of a first filter element (10) to an input of a second filter element (12) and is the longest of the three connecting segments (9a, 9b, 9c).

2. Connecting device (8) according to Claim 1, wherein the at least one filter element (10, 12) has at least one attachment piece (14, 16), and wherein at least one connecting segment (9a, 9b, 9c) is pushed onto the at least one attachment piece (14, 16).

3. Connecting device (8) according to either of the preceding claims, wherein the at least one connecting segment (9a, 9b, 9c) is a hose segment.

4. Connecting device (8) according to any of the preceding claims, wherein at least one filter element (10, 12) contains a paper filter.

5. Connecting device (8) according to any of the preceding claims, wherein the at least one filter element (10, 12) has a gas-tight and / or an at least partially transparent housing.

6. Connecting device (8) according to any of the preceding claims, wherein the at least one filter element (10, 12) is designed such that gas flows through the filter (20) from its outer side to its inner side.

7. Connecting device (8) according to any of the preceding claims, wherein the filter elements (10, 12) and filter (20) are produced from a metal-free material, in particular from a material which prevents accumulation and subsequent outdiffusion of the gases to be measured, in particular HC, CO, CO2, O2, NOx.

8. Connecting device (8) according to any of the preceding claims, wherein the at least one filter element (10, 12) has a filter (20), wherein the filter (20) has a defined pressure difference, which does not exceed an upper limit, depending on the flow rate.

9. Exhaust-gas measuring system having an exhaust-gas measuring apparatus (6), an exhaust-gas probe (4) and a connecting device (8) according to any of the preceding claims, wherein the connecting device (8) connects the exhaust-gas probe (4) to an input of the exhaust-gas measuring apparatus (6) in order to allow exhaust-gas flow from the exhaust-gas probe (4) into the exhaust-gas measuring apparatus (6).

10. Exhaust-gas measuring system (2) according to Claim 9, wherein a HEPA fine filter element (12) is arranged directly upstream of the input of the exhaust-gas measuring apparatus (6).

11. Exhaust-gas measuring system (2) according to Claim 9 or 10, wherein the exhaust-gas measuring apparatus (6) is designed to measure exhaust gases from a petrol engine.

12. Use of an exhaust-gas measuring system (2) according to any of Claims 9 to 11 for measuring exhaust gases from a diesel engine.