Exhaust gas sampling probe with hollow body

Description

[0001] The present invention relates to an exhaust gas sampling probe having a probe inlet, a probe outlet, and a gas channel connecting the probe inlet to the probe outlet. Furthermore, the present invention relates to the use of an exhaust gas sampling probe in an emissions measuring device and to an emissions measuring device having such an exhaust gas sampling probe.

[0002] Emission measuring instruments for measuring exhaust emissions, such as hydrocarbons (HC), carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), or particulate matter, for example from internal combustion engines or industrial processes, are well known. Emission measuring instruments are available in a wide variety of designs, with different measuring principles being applied depending on the model. One thing that many emission measuring instruments have in common, however, is that they each feature an exhaust gas sampling probe, which is used to sample exhaust gas from an exhaust stream. Typically, an exhaust gas to be analyzed flows within such an exhaust stream, which is partially or completely sampled and fed to an emission measuring instrument. The sampled exhaust gas can be processed in the emission measuring instrument as required (e.g., water separation, removal of volatile components, etc.).), diluted as needed (e.g., in a dilution tunnel), and / or fed to one or more measuring stages. Typically, the exhaust gas sampling probe is inserted directly into the exhaust pipe / exhaust of a combustion engine, a vehicle, or an industrial process and is firmly anchored, for example, by clamping, during the measurement process.

[0003] To ensure the proper and satisfactory operation of an emissions measuring device, a number of aspects must be taken into account. In this case, it is important to ensure that emissions measuring devices are designed to be robust against external influences that can affect an emissions measuring device and its components in the context of exhaust gas tests. High temperatures are a key external influence in this regard. The ingress of soot and soot particles into the gas duct of an emissions measuring device must also be highlighted in this context. An accumulation of soot or soot particles or other products of the combustion process can block a gas duct. In the worst case, soot particles, but also other particles or general foreign bodies, can lead to electrical short circuits in the emissions measuring device and thus damage electrical components located in the emissions measuring device.An important example of this is short circuits on a corona wire provided in the emission measuring device.

[0004] With regard to the effects of temperature and / or soot, but also other influences on an emissions measuring device, particular attention must be paid to the associated effects on the aforementioned exhaust gas sampling probes. Due to their typical positioning in an exhaust pipe / in an exhaust, exhaust gas sampling probes are particularly affected by temperature, soot, and other environmental influences. It is therefore desirable to design exhaust gas sampling probes in particular to be robust against environmental influences. This applies particularly to the area of ​​the probe inlet of an exhaust gas sampling probe, through which exhaust gas flows into the exhaust gas sampling probe. It is also advantageous to design entire exhaust gas sampling probes or individual components of exhaust gas sampling probes, e.g. components from the area of ​​the probe inlet, to be exchangeable and replaceable with spare parts.

[0005] Although problems associated with temperature and soot influences in emission measuring instruments are known, these aspects are only inadequately addressed in the state of the art.

[0006] For example, US 3,382,721 A and EP 2428790 A1 describe exhaust gas sampling probes with a clamping device for securing them to an exhaust pipe. In both documents, the exhaust gas sampling probes feature lateral inlet openings into the gas channels of the respective exhaust gas sampling probes, which are exposed unprotected to hot, soot-laden exhaust gas. Probe inlets equipped with lateral inlet openings represent particularly sensitive areas of exhaust gas sampling probes, which can be easily damaged, especially in workshop operation. Neither US 3,382,721 A nor EP 2428790 A1 provide options for protecting these areas or for replacing easily damaged components. Another exhaust gas sampling probe is described in document WO2015044256A1.

[0007] KR 101917244 B1 also describes an exhaust gas sampling probe for sampling exhaust gas from a vehicle exhaust. The focus of this document is on ensuring a specified distance from the inner wall of the exhaust. Therefore, KR 101917244 B1 does not address the effects of temperature and soot, nor the associated robustness considerations.

[0008] All of the exhaust gas sampling probes described in the cited documents therefore have disadvantages, particularly with regard to the important aspect of robustness. It is therefore an object of the present invention to provide an exhaust gas sampling probe that is improved, especially with regard to its robustness.

[0009] This object is achieved for an exhaust gas sampling probe mentioned at the outset by the features of the independent claims. The independent claims describe an exhaust gas sampling probe with a probe inlet, a probe outlet, and a gas channel connecting the probe inlet to the probe outlet. In particular, a tubular exhaust gas sampling probe is provided with a probe inlet arranged at a first axial end of the exhaust gas sampling probe, a probe outlet arranged at an opposite second axial end of the exhaust gas sampling probe, and a gas channel extending axially through the exhaust gas sampling probe and connecting the probe inlet to the probe outlet for sampling an exhaust gas that can flow from the probe inlet through the gas channel to the probe outlet. The independent claims further describe the use of an exhaust gas sampling probe according to the invention in an emissions measuring device and an emissions measuring device.

[0010] According to the invention, a hollow body is arranged at least partially, preferably completely, in the gas channel of the exhaust gas sampling probe, wherein the hollow body has a cavity surrounded by a lateral surface, at least one inlet opening into the cavity arranged in the lateral surface of the hollow body, at least one outlet opening arranged on a side of the hollow body facing the probe outlet and a fluid-tightly closed end face facing away from the probe outlet.According to the invention, a first hollow body section is formed on the hollow body between the closed end face and at least one inlet opening closest to the outlet opening, which first hollow body section runs along a longitudinal extent of the hollow body, the outer cross-sectional area of ​​which is defined by its lateral surface and oriented normal to the longitudinal extent of the hollow body being smaller than an inner cross-sectional area of ​​the gas channel in the region of the first hollow body section, so that in the region of the first hollow body section in the gas channel at least one gap is formed, which connects the probe inlet to the at least one inlet opening in a flow-through manner.According to the invention, a second hollow body section is formed along the longitudinal extent of the hollow body between the first hollow body section and the outlet opening, the outer cross-sectional area of ​​which, oriented perpendicular to the longitudinal extent of the hollow body, corresponds to the inner cross-sectional area of ​​the gas channel, so that a flow path through the exhaust gas sampling probe runs from the probe inlet through the at least one gap via the at least one inlet opening through the cavity of the hollow body via the at least one outlet opening to the probe outlet. Along the flow path, exhaust gas can flow through the exhaust gas sampling probe from the probe inlet through the at least one gap via the at least one inlet opening through the cavity of the hollow body via the at least one outlet opening to the probe outlet.

[0011] The described design of an exhaust gas sampling probe according to the invention enables, on the one hand, effective protection of the gas channel of the exhaust gas sampling probe and downstream measuring devices against potentially harmful particles, such as large soot particles. As will be explained in detail below, large and potentially harmful particles cannot, for several reasons, enter the cavity of the hollow body in an exhaust gas sampling probe according to the invention and thus cannot subsequently flow or move through the gas channel. In addition, the component which contributes significantly to this protection, namely the hollow body, is considerably better protected against external influences compared to exhaust gas sampling probes known from the prior art.Completely encased by the outer wall of the exhaust gas sampling probe, the hollow body is protected from external influences such as force, impacts, or shocks, particularly in the sometimes harsh workshop environment. The desired goal of increased robustness of an exhaust gas sampling probe is thus achieved.

[0012] In one variant of the invention, at least one sealing surface is formed on a side of the second hollow body section facing away from the probe inlet. When the hollow body is assembled, this sealing surface interacts with a corresponding sealing surface on the inner surface of the gas channel. This ensures that exhaust gas follows the described flow path through the inlet opening into the interior of the hollow body and further into the gas channel.

[0013] In a particularly advantageous manner, the hollow body is detachably arranged and / or can be arranged in the gas duct, preferably connected to the inner wall of the gas duct. This allows for a number of additional advantages. On the one hand, a hollow body can be removed from the exhaust gas sampling probe for cleaning purposes and reinserted into the exhaust gas sampling probe after cleaning. On the other hand, a detachable hollow body makes it possible to completely replace a potentially defective hollow body. The detachable arrangement can be achieved, for example, by screwing, locking, or clamping, although other solutions are also possible.

[0014] Based on the detachability of a hollow body, it is often advantageous to provide a tool holder on the side of the fluid-tight end face of the hollow body facing away from the outlet opening. This allows the described removal and reinsertion of a hollow body into an exhaust gas sampling probe to be carried out quickly and effectively using a tool, such as an Allen key.

[0015] Furthermore, a two-part or multi-part design of an exhaust gas sampling probe according to the invention is relevant in practice, comprising the hollow body, a probe tip forming the first axial end of the exhaust gas sampling probe, and a probe body axially adjoining the probe tip. In particular, the first axial end of the exhaust gas sampling probe, which has the probe inlet, can often be designed in a complex and detailed manner (e.g., by external coupling parts, support elements, the arrangement of a filter, etc.). Due to this complexity, it is often advantageous to manufacture this special area of ​​an exhaust gas sampling probe, usually referred to as the probe tip, separately. A probe tip can then be connected, for example, by pressing, welding, or screwing, to the part of the exhaust gas sampling probe that axially adjoins the probe tip and is usually referred to as the probe body.In typical cases, it is advantageous to arrange the hollow body according to the invention in the region of the first axial end of the exhaust gas sampling probe in order to prevent potentially harmful particles from entering the exhaust gas sampling probe right from the start. Therefore, a probe tip is particularly advantageously manufactured in such a way that a hollow body according to the invention can be arranged at least partially, preferably completely, within the probe tip.

[0016] In this case, a probe tip can advantageously also be designed as a coupling part of a connecting coupling. In particular, the probe tip is designed as the first or second coupling part of a connecting coupling. For self-testing and inspection purposes, an exhaust gas sampling probe can in such a case be connected to a self-test unit, which has a complementary coupling part for connection to the exhaust gas sampling probe. Especially in workshop operation, an exhaust gas sampling probe and a connectable emissions measuring device can be quickly, easily, and reliably connected to a self-test unit for testing. Such a self-test unit can, for example, be designed as part of an emissions measuring device.

[0017] In a further advantageous embodiment, at least one radially projecting support element is provided on the outer wall of an exhaust gas sampling probe according to the invention, preferably in the region of the probe tip. In particular, the support element can be designed to be circumferential, i.e., surrounding the probe tip. This makes it possible, for example, when the exhaust gas sampling probe is used in an exhaust pipe or exhaust, to always ensure a predetermined distance from the inner wall of the exhaust pipe or exhaust.

[0018] In a further variant of the invention, the radial cross-sectional area of ​​the gap substantially corresponds to the sum of the cross-sectional areas of the inlet openings provided in the outer surface of the hollow body. Preferably, a predetermined maximum deviation E max is specified between the radial cross-sectional area of ​​the gap and the sum of the cross-sectional areas of the inlet openings. In other words, the radial cross-sectional area of ​​the gap deviates by no more than a predetermined maximum deviation E max from the sum of the cross-sectional areas of the inlet openings provided in the outer surface of the hollow body. Preferably, the predetermined maximum deviation E max can be specified as a relative value of the sum of the cross-sectional areas of the inlet openings. The maximum deviation E max can correspond to a relative value of 30%, a relative value of 20%, or a relative value of 10%.

[0019] In this way, the pressure conditions in the area of ​​the first axial end of the exhaust gas sampling probe, which has the probe inlet, can be specifically influenced. Among other things, this can stabilize the operation of the exhaust gas sampling probe or a connected emissions measuring device in the event of transient pressure changes in the exhaust stream or in an exhaust pipe in which the exhaust gas sampling probe is located.

[0020] When designing an exhaust gas sampling probe according to the invention, the respective diameters of the inlet openings provided in the outer surface of the hollow body are each smaller than a predetermined maximum diameter D max . The maximum diameter D max can be in a value range from 10 µm to 100 mm, or in a value range from 100 µm to 10 mm, or in a value range from 500 µm to 10 mm, in order to effectively prevent the entry of large and potentially harmful soot particles.

[0021] To attach the exhaust gas sampling probe to an exhaust pipe, a fastening unit can be provided on the outer wall of the exhaust gas sampling probe, preferably in the area of ​​the probe outlet, for attaching the exhaust gas sampling probe to an exhaust pipe. This fastening unit can be designed, among other things, in the form of a spring clip. In particular, this can be an exhaust pipe of a vehicle or a stationary unit with an internal combustion engine or another power generation unit that emits corresponding exhaust gases.

[0022] An exhaust gas sampling probe according to the invention can be used to sample exhaust gas from an exhaust gas stream and feed it to an emissions measuring device. For this purpose, an exhaust line can be connected to an emissions measuring device, with the exhaust gas sampling probe being provided for sampling exhaust gas at the end of the exhaust line facing away from the emissions measuring device.

[0023] The present invention is described below with reference to the Figuren 1 bis 6 which show exemplary, schematic and non-limiting advantageous embodiments of the invention. Fig. 1 a schematic, perspective view of an exhaust gas sampling probe according to the invention, Fig. 2 a sectional view along a longitudinal extent of a part of an exhaust gas sampling probe according to the invention with a hollow body according to the invention, Fig. 3 a hollow body in perspective view, Fig. 4 a hollow body in a sectional view along a longitudinal extension of the hollow body, Fig. 5 the use of an exhaust gas sampling probe according to the invention for sampling exhaust gas from an exhaust of a vehicle and forwarding it to an emission measuring device, and Fig. 6 an exhaust gas sampling probe connected twice to an emissions measuring device.

[0024] Fig. 1 shows a schematic representation of an exhaust gas sampling probe 1 in accordance with the present invention. The illustrated exhaust gas sampling probe 1 is essentially tubular and has a probe inlet 201 arranged at a first axial end of the exhaust gas sampling probe 1 and a probe outlet 202 arranged at an opposite second axial end of the exhaust gas sampling probe 1. The probe inlet 201 is mechanically connected to the probe outlet 202 via a probe body 4, wherein the probe body 4 has a (in Fig. 1 not shown) in the axial direction, so that exhaust gas can flow into the exhaust gas sampling probe 1 via the probe inlet 201, flow through the exhaust gas sampling probe 1 through the gas channel 200 and finally leave the exhaust gas sampling probe 1 again through the probe outlet 202.

[0025] In other words, the exhaust gas sampling probe 1 is tubular with a probe inlet 201 arranged at a first axial end of the exhaust gas sampling probe 1, a probe outlet 202 arranged at a second axial end of the exhaust gas sampling probe 1, preferably opposite the first end, and a gas channel 200 extending axially through the interior of the exhaust gas sampling probe 1 and connecting the probe inlet 201 to the probe outlet 202 for sampling an exhaust gas that can flow from the probe inlet 201 through the gas channel 200 to the probe outlet 202.

[0026] The exhaust gas sampling probe 1 is preferably made of stainless steel to withstand chemically aggressive exhaust gas components and to prevent excessive cooling of the exhaust gas in the exhaust gas sampling probe 1. However, manufacturing from other materials is also conceivable.

[0027] As will be explained in detail below, in the present context, in particular the first axial end of the exhaust gas sampling probe 1, which has the probe inlet 201, can be designed in a complex and detailed manner (e.g., by means of external coupling parts, support elements, the arrangement of a filter, etc.). This special area of ​​an exhaust gas sampling probe 1 is in many cases, and thus also in the course of the following explanations, specifically referred to as probe tip 3. In the case of a one-piece design of an exhaust gas sampling probe 1, a probe tip 3 can form a one-piece mechanical body with the probe body 4 and can be permanently connected to the probe body 4. In the case of a multi-piece design of an exhaust gas sampling probe 1, a probe tip 3 can also represent a separate component from the probe body 4 and can be detachable (e.g., by screwing) or non-detachable (e.g.,by welding or pressing) to the probe body 4.

[0028] Furthermore, in Fig. 1 A fastening unit 5 for fastening the exhaust gas sampling probe 1 is shown, which is arranged in the region of the probe outlet 202. The fastening unit 5 can be designed, among other things, in the form of a spring clamp and serves to fix or clamp the exhaust gas sampling probe 1 at a selected location, such as on an exhaust pipe or on the exhaust of a vehicle. However, a design of the exhaust gas sampling probe 1 with a differently implemented fastening unit 5 is also conceivable, as is an exhaust gas sampling probe 1 without a fastening unit 5.

[0029] According to the above explanations, a Fig. 1 The exhaust gas sampling probe 1 shown can be inserted, for example, into an exhaust pipe, e.g. of a motor vehicle (motor vehicle), fixed by means of the fastening unit 5, receive the exhaust gas to be analyzed or examined through the probe inlet 201, guide the collected exhaust gas through the gas channel 200 provided in the probe body 4 through the exhaust gas sampling probe 1, and then output the exhaust gas again via the probe outlet 202. Starting from the probe outlet 202, the extracted exhaust gas can be passed on, in particular via a further exhaust line 6, to an emission measuring device 10, as in Fig. 5 is shown.

[0030] For a more detailed discussion of the invention, Fig. 2 The first axial end of the exhaust gas sampling probe 1 with the probe inlet 201 in a sectional view. The illustrated first axial end of the exhaust gas sampling probe 1 is constructed in several parts, i.e., a probe tip 3 is provided that is (initially) separate from the probe body 4. In this case, the probe body 4 and the probe tip 3 are permanently pressed together. In principle, however, other methods for connecting a probe tip 3 and a probe body 4 are also conceivable, such as welding, gluing, or soldering.

[0031] In the illustrated case, the outer wall of the probe tip 3 has a coupling part 111 of a connecting coupling at one axial end and a contour suitable for pressing with the probe body 4 at the other axial end. In this embodiment, a radially projecting support element 110 is located axially between them for positioning the exhaust gas sampling probe 1 in an exhaust pipe. The coupling part 111 and the support element 110 will be discussed separately later.

[0032] The probe body 4 encloses a gas channel 200 through which exhaust gas can flow in the axial direction from the probe inlet 201 to the probe outlet 202. In order not to interrupt the flow-through connection between the probe inlet 201 and the probe outlet 202, the gas channel 200 is in the Fig. 2 shown embodiment through the probe tip 3 to the probe inlet 201.

[0033] According to the invention, a hollow body 100 is arranged in the gas channel 200, in the embodiment shown in the section of the gas channel 200 enclosed by the probe tip 3. The longitudinal extension 100a of the hollow body essentially coincides with the longitudinal axis of the hollow body 4.

[0034] The exhaust gas sampling probe 1 shown is designed in several parts, with the hollow body 100, a probe tip 3 forming the first axial end of the exhaust gas sampling probe 1 and receiving the hollow body 100, and a probe body 4 adjoining the probe tip 3 in the axial direction.

[0035] In the illustrated embodiment, the hollow body 100 is arranged completely in the gas channel 200, but in variants it can also be only partially accommodated in the gas channel 200. The hollow body 100 has a cavity 108 formed in the interior of the hollow body 100 and surrounded by a lateral surface. The cavity 108 is connected to the surroundings of the hollow body 100 via several inlet openings 105 arranged in the lateral surface of the hollow body 100. On a side of the hollow body 100 facing the probe outlet 202, an outlet opening 104 is provided which connects the cavity 108 to the gas channel 200 in a way that allows flow through it. An end face 103 facing away from the probe outlet 202 is designed to be fluid-tight. In the Fig. 2 In the embodiment shown, the hollow body 100 is arranged within the probe tip 3. As mentioned, embodiments of an exhaust gas sampling probe 1 without a probe tip 3 are also conceivable within the scope of the invention. In such cases, the hollow body 100 can be arranged in a section of the gas channel 200 enclosed by the probe body 4.

[0036] In order to ensure a continuous flow path from the probe inlet 201 to the probe outlet 202 for the exhaust gas to be extracted, despite the hollow body 100 being arranged in the gas channel 200, the hollow body 100 is designed such that a first hollow body section 101 is formed between the closed end face 103 of the hollow body 100 and at least one inlet opening 105 in the lateral surface of the hollow body 100. If multiple inlet openings 105 are provided, the aforementioned one inlet opening 105 used to define the first hollow body section 101 is the inlet opening 105 closest to the outlet opening 104. The inlet opening 105 closest to the outlet opening 104 has the shortest axial distance from the outlet opening 104.The outer cross-sectional area of ​​the first axial hollow body section 101 oriented normal to a longitudinal extension 100a of the hollow body 100, which is defined by the lateral surface of the first axial hollow body section 101, is adapted to the geometry of the gas channel 200.

[0037] According to the invention, the outer cross-sectional area of ​​the first hollow body section 101, which is defined by the lateral surface of the first axial hollow body section 101, is selected to be smaller than an inner cross-sectional area of ​​the gas channel 200 in the region of the first hollow body section 101, said inner cross-sectional area running normal to the longitudinal extent 100a of the hollow body 100, so that at least one gap 106 is formed in the gas channel 200 in the region of the first hollow body section 101. While in the illustrated embodiment the gap 106 is designed as a circumferential annular gap, variants are also conceivable in which the gap 106 represents a ring segment or the gap 106 is implemented as one or more grooves in a direction parallel to the longitudinal extent 100a of the hollow body 100 in the lateral surface of the first hollow body section 101.The gap 106 is thus formed between the inner surface of the gas channel 200 and the outer surface of the hollow body 100, in particular of the first hollow body section 101, and extends at least from the probe inlet 201 to one inlet opening 105 or to several inlet openings 105.

[0038] The gap 106 creates a flow-through connection between the probe inlet 201 of the exhaust gas sampling probe 1 with at least one inlet opening 105 of the hollow body 100 to the probe outlet 202. In this way, the gas channel 200 is not completely closed by the hollow body 100.

[0039] In addition to the first hollow body section 101, Fig. 2 a second hollow body section 102 of the hollow body 100, which is formed along the longitudinal extent 100a of the hollow body 100 between the first hollow body section 101 and the outlet opening 104. The second hollow body section 102 is provided in the illustrated embodiment between the inlet opening(s) 105 located furthest away from the probe inlet 201 in the axial direction and the outlet opening 104 of the hollow body 100. The second hollow body section 102 can, as shown in the figures, cover the entire area between the first hollow body section 101 and the outlet opening 104, but can also extend over only a part of this area. As in the embodiment according to Fig. 2 As shown, the second hollow body section 102 can have a sealing surface 109 on its outer surface, which interacts with a corresponding sealing surface on the inner wall of the gas channel 200. In other words, a sealing surface 109 is formed on a side of the second hollow body section 102 facing away from the probe inlet 201, which sealing surface interacts with a corresponding sealing surface on the inner surface of the gas channel 200 when the hollow body 100 is mounted in the gas channel 200.

[0040] The corresponding sealing surfaces 109 can, for example, be a thread with which the hollow body 100 is screwed or can be screwed into the gas channel 200. Due to this feature, exhaust gas can only flow from the probe inlet 201 through the at least one gap 106 via the at least one inlet opening 105 through the cavity 108 of the hollow body 100 via the at least one outlet opening 104 to the probe outlet 202.

[0041] On the other hand, if the hollow body 100 and the inner wall of the gas channel touch each other at the end face in the region of the end face of the hollow body 100 facing away from the probe inlet 201, a sealing surface 109 can also be arranged in the region of an end face of the hollow body 100 facing away from the probe inlet 201. A sealing surface 109 arranged at the end face can be particularly advantageous for a hollow body 100 fixed in the gas channel 200 by means of a plug connection.

[0042] Fig. 2 shows such a solution, in which the gas channel 200 in the region of the probe tip 3, starting from the probe inlet 201, has a first section with a first diameter and a second section with a second diameter, wherein the second diameter is smaller than the first diameter and a particularly circumferential shoulder is formed at the transition from the first to the second section. The hollow body 100 is received in the first section. The circumferential shoulder, against which the end face of the hollow body 100 facing the probe outlet 202 rests with the outlet opening 104 in the assembled state of the hollow body 100, thus forms the sealing surface of the inner surface of the gas channel 200 that interacts with the sealing surface 109.

[0043] Likewise, sealing surfaces 109 can be provided both on the end face and on the lateral surface of the second axial hollow body section 102. However, one or more sealing surfaces 109 can also be provided exclusively on the lateral surface of the second axial hollow body section 102 or exclusively on the end face facing away from the probe inlet 201, each of which interacts with a matching sealing surface on the inner wall of the gas channel 200. Likewise, regions of the lateral surface of the second axial hollow body section 102 can be designed as protruding radial steps that form a sealing surface 109.

[0044] The provision of the described sealing surfaces 109 ensures that exhaust gas sampled with the exhaust gas sampling probe 1 can only flow along a flow path(s) that run through one of the inlet openings 105 in the outer surface of the hollow body 100. If the inlet openings 105 and / or the gap 106 are selected to be sufficiently small, this can effectively prevent potentially harmful soot particles, which, due to their size, could lead to blockages in the gas channel 200 or to damage in an emissions measuring device 10 that may be connected to the exhaust gas sampling probe 1, from entering the gas channel 200 at all. This effect can have a decisive impact on the service life of an emissions measuring device 10, but also on the service life of an associated exhaust gas sampling probe 1.

[0045] As explained in detail below, the aforementioned flow path(s) exhibit(s) some significant changes in direction or deflections. Larger soot particles or other foreign bodies are often unable to follow significant changes in direction or deflections at the flow velocities encountered in practice, among other things due to their mass moment of inertia. This type of deposition is also referred to as impaction. Such large soot particles can rebound from the closed end face 103 or collect in the gap 106. This also prevents soot particles from entering the gas channel 200.

[0046] In an advantageous manner, to determine the sizes of the respective inlet openings 105, the diameters of the inlet openings 105 can each be specified smaller than a predetermined maximum diameter D max . The maximum diameter D max can be specified in a value range from 10 µm to 100 mm, or in a value range from 100 µm to 10 mm, or in a value range from 500 µm to 10 mm, in order to ensure suitable sizes of the inlet openings 105 for different particle sizes, which can vary in different applications (trucks, cars, motorcycles).

[0047] In a comparable manner, the cross-sectional area of ​​the gap 106, which forms in the region of the first axial hollow body section 101 in the gas channel 200 between the inner wall of the gas channel 200 and the hollow body 100, can also be chosen to be sufficiently small in order to provide a barrier for large soot particles or other particles already at the probe inlet 201.

[0048] To specify the cross-sectional area of ​​the gap 106, the sum of the cross-sectional areas of the inlet openings 105 provided in the outer surface of the hollow body 100 can be determined. Based on this sum of the cross-sectional areas of the inlet openings 105 provided in the outer surface of the hollow body 100, a maximum deviation E max can be specified for the cross-sectional area of ​​the gap 106, by which the cross-sectional area of ​​the gap 106 may not deviate from the sum of the cross-sectional areas of the inlet openings 105 provided in the outer surface of the hollow body 100.

[0049] The specified maximum deviation E max can be specified as a relative value of the sum of the cross-sectional areas of the inlet openings 105 provided in the outer surface of the hollow body 100, whereby the maximum deviation E max can correspond to a relative value of 30%, or a relative value of 20%, or a relative value of 10%. By combining sufficiently small inlet openings 105 and a cross-sectional area of ​​the gap 106 suitably selected depending on the size of the inlet openings 105, the entry of excessively large and thus potentially damaging soot particles or other particles or general foreign bodies into the gas channel 200 can be prevented.

[0050] The separation of damaging soot particles or other particles or general foreign bodies can take place by form closure if soot particles or other particles or general foreign bodies cannot overcome the inlet openings 105 for geometric reasons. The separation of damaging soot particles or other particles or general foreign bodies can also take place by impaction. In this context, impaction is understood as a process in which, for example, soot particles cannot follow changes in direction of a gas flow due to their inertia. In the case of impaction, the inlet openings 105 and / or the gap 106 and / or the entire hollow body 100 can be designed such that inertia-based separation can take place for soot particles or other particles or general foreign bodies from a size of 0.5 µm to 1 mm.This design can be made depending on an expected / assumed / given exhaust gas flow, or depending on properties of an expected / assumed / given exhaust gas flow, such as its flow velocity, mass density, etc.

[0051] Ideally, the cross-sectional area of ​​the gap 106 and the sum of the cross-sectional areas of the inlet openings 105 provided in the outer surface of the hollow body 100 are identical or preferably do not differ from each other by more than a predetermined maximum deviation E max . This can, in particular, prevent the formation of large back pressures in the gap 106. Pressure fluctuations associated with (large) back pressures in the area of ​​the probe inlet 201 can, among other things, have a negative impact on the further analysis of the sampled exhaust gas in an emissions measuring device 10, which is effectively prevented by the equality of the aforementioned areas.

[0052] On the other hand, during suction operation of an exhaust gas sampling probe 1 or an emissions measuring device 10, certain pressure conditions or a specific pressure drop across the probe tip 3 can be ensured by appropriately matching the cross-sectional area of ​​the gap 106 to the sum of the cross-sectional areas of the inlet openings 105. Such matching of the cross-sectional areas can have a stabilizing effect, particularly with regard to transient pressure changes in an exhaust pipe in which the exhaust gas sampling probe 1 is arranged.

[0053] Furthermore, the Fig. 2 The hollow body 100 shown is detachably arranged and / or arrangeable in the gas channel 200 and, in the illustrated embodiment, is connected to the inner wall of the gas channel 200. In this specific case, the outer surface of the second hollow body section 102 is designed as an external thread. The corresponding section of the inner wall of the probe tip 3 is designed as a corresponding internal thread, so that the hollow body 100 can be screwed to the probe tip 3 and thus to the gas channel 200. The external thread provided on the hollow body 100 therefore forms the aforementioned first sealing surface 109, and the internal thread provided in the probe tip 3 or in the gas channel 200 forms the aforementioned opposite second sealing surface. In addition, the above-described shoulder in the gas channel 200 has a sealing effect.

[0054] A detachable connection between the hollow body 100 and the inner wall of the gas channel 200 is particularly advantageous with regard to the maintainability of an exhaust gas sampling probe 1. A detachable connection makes cleaning and replacing a hollow body 100 easy in the event of a defect or damage.

[0055] In order to be able to screw the hollow body 100 into the probe tip 3 and then loosen it again, a tool holder 107 is provided on the side of the fluid-tight end face 103 of the hollow body 100 facing away from the outlet opening 104. In this way, the hollow body 100 can be assembled and disassembled with little effort, particularly during maintenance, for example in order to clean the hollow body 100 or to replace the hollow body 100. A tool holder 107 is to be seen as an optional extension of the hollow body 100 according to the invention and is not absolutely necessary for the inventive protection of an emission measuring device 10 against excessively large particles. A tool holder 107 can be designed as a polygonal hole for receiving a polygonal wrench, e.g. as a square hole for receiving a square wrench or as a hexagonal hole for receiving a hexagonal wrench.

[0056] A recess as a tool holder 107 is provided, as shown in Fig. 2 shown, however, is not to be understood as a hole extending into the cavity 108 of the hollow body, which would result in the frontal closure of the front side 103 of the hollow body 100 being lost. Receptacles for other tools, such as wrenches, ring spanners, pipe wrenches, or socket wrenches, are also conceivable for implementing a tool holder 107. In the case of a non-detachable connection between the hollow body 100 and the probe tip 3 or probe body 4, or in the case of a plug-in connection between the hollow body 100 and the probe tip 3 or probe body 4, a tool holder 107 can also be dispensed with.

[0057] Possible flow conditions that can occur around a hollow body 100 according to the invention are further described in Fig. 3 shown. Fig. 3 On the one hand, it depicts the effect of a fluid-tightly sealed end face 103 of a hollow body 100. Flow paths converging frontally toward the sealed end face 103 of the hollow body 100 are deflected from the end face 103 and move first along the sealed end face 103 and then along the lateral surface of the hollow body 100 through the gap 106. The flow paths shown ultimately reach the cavity 108 inside the hollow body 100 via one or more inlet openings 105. Large soot particles cannot usually follow the aforementioned deflections of the flow paths at the flow velocities occurring in practice and consequently bounce off the end face 103. With regard to its effect on large soot particles, an end face 103 can therefore also be regarded as a baffle plate.

[0058] In addition to the first axial hollow body section 101 and the second axial hollow body section 102, Fig. 3 the outlet opening 104 is shown, which connects the cavity 108 to the gas channel 200 in a flow-through manner, so that exhaust gas can flow from the cavity 108 of the hollow body 100 via the at least one outlet opening 104 to the probe outlet 202. The outlet opening 104 extends over almost the entire cross-sectional area of ​​the end face of the hollow body 100 facing away from the probe inlet 201. One of the purposes of such a comparatively large outlet opening 104 is to minimize the flow resistance effective at the transition between the hollow body 100 and the gas channel 200. Also conceivable is a significantly smaller outlet opening 104, or several small outlet openings 104 distributed over the end face of the hollow body facing away from the probe inlet 201, in order to provide a further obstacle for any soot particles that may still remain in the exhaust gas at this point.

[0059] Fig. 4 shows flow conditions occurring in a hollow body 100 in the form of a sectional view with a section along a longitudinal extension 100a of the hollow body 100. The inner surface of the gas channel 200 is shown in dashed lines. In addition to the already discussed components of an exhaust gas sampling probe 1 according to the invention (first hollow body section 101, second hollow body section 102, closed end face 103, outlet opening 104, inlet openings 105, tool holder 107, cavity 108, sealing surfaces 109, probe inlet 201) is shown in Fig. 4 In particular, the effect of gap 106 is evident. All flow paths remaining from probe inlet 201 and toward probe outlet 202 run through gap 106.

[0060] How an exhaust gas sampling probe 1 according to the invention can be used in practice is described in Fig. 5 Specifically, Fig. 5 an emissions measuring device 10, to which an exhaust line 6 is connected. At the end of the exhaust line 6 facing away from the emissions measuring device 10, an exhaust gas sampling probe 1 according to the invention is connected for sampling exhaust gas. The exhaust gas sampling probe 1 is fixed to the exhaust of a vehicle by means of a fastening unit 5. The radially projecting support element 110 provided on the probe tip 3 ensures that the exhaust gas sampling probe 1 always maintains a predetermined distance from the inner wall of the exhaust and does not rest against the inner wall of the exhaust. Fig. 5 In the arrangement shown, exhaust gas can flow from the exhaust, via the exhaust gas sampling probe 1, into the exhaust line 6 up to the emission measuring device 10 in accordance with the preceding statements, in order to be examined or analyzed there.

[0061] In practice, it is necessary to subject an emission measuring device 10 to regular checks. This can be an adjustment, for example, by zeroing with a zero gas (pure gas without emission components, e.g., filtered ambient air) to set a zero point for the measurement, or by calibration with a calibration gas (gas with defined emission components). A leak test of the probe system (exhaust gas sampling probe 1 with the exhaust line 6 up to the emission measuring device 10) or of the entire gas path within the emission measuring device 10 must also usually be carried out regularly. Therefore, particularly in workshop operation and when used by maintenance personnel, it is advantageous if both the adjustment and the leak test are as simple to perform as possible.

[0062] In order to make such checks as simple as possible, an exhaust gas sampling probe 1 according to the invention can, in a particularly advantageous manner, have a probe tip 3 whose outer wall is designed as a coupling part 111 of a connecting coupling.

[0063] In an advantageous manner, a self-test unit 11 can additionally be provided in an emission measuring device 10 used in combination with the exhaust gas sampling probe 1, on which a coupling part of a connecting coupling corresponding to the coupling part 111 of the probe tip 3 is arranged, wherein the first coupling part 111 of the probe tip 3 can be connected to the second coupling part on the self-test unit 11 to carry out a self-test.

[0064] The probe tip 3 of the exhaust gas sampling probe 1 thus fulfills a dual function: on the one hand, the exhaust gas sampling, and on the other, a connection as part of the connecting coupling. This makes a self-test extremely easy to perform. Only the coupling part 111 of the probe tip 3 needs to be connected to the coupling part on the self-test unit 11. The self-test unit 11 has all other features required for performing a self-test, in particular a leak test and / or zeroing or calibration. No additional parts or components are required for the self-test.

[0065] An exhaust gas sampling probe 1 connected twice to an emission measuring device 10 according to the previous embodiments is shown in Fig. 6 shown. Fig. 6 also shows that the radially projecting support element 110, in addition to its actual function, also serves as a stop when installing the probe tip 3 in a coupling receptacle (in Fig. 6 on the emission measuring device 10).

Claims

1. Exhaust gas sampling probe (1) comprising a probe input (201), a probe output (202) and a gas channel (200) which connects the probe input (201) to the probe output (202), characterized in that a hollow body (100) is arranged at least partly, preferably completely, in the gas channel (200) of the exhaust gas sampling probe (1), the hollow body (100) having a cavity (108) which is surrounded by a lateral surface of the hollow body (100), at least one inlet opening (105) which is arranged in the lateral surface of the hollow body (100), at least one outlet opening (104) which is arranged on a side of the hollow body (100) facing the probe output (202), and a fluid-tight, sealed end face (103) which faces away from the probe output (202), in that a first hollow body portion (101) is formed on the hollow body (100) between the sealed end face (103) and at least one inlet opening (105) closest to the outlet opening (104), which first hollow body portion extends along a longitudinal extension (100a) of the hollow body (100) and of which first hollow body portion an outer cross-sectional area, which is defined by its lateral surface and oriented normally with respect to the longitudinal extension (100a) of the hollow body (100), is smaller than an inner cross-sectional area of the gas channel (200) in the region of the first axial hollow body portion (101), so that at least one gap (106) is formed in the region of the first hollow body portion (101) in the gas channel (200), which gap connects the probe input (201) to the at least one inlet opening (105) in a way that allows flow, and in that a second hollow body portion (102) is formed along the longitudinal extension (100a) of the hollow body (100) between the first hollow body portion (101) and the outlet opening (104), of which second hollow body portion an outer cross-sectional area, which is oriented normally with respect to the longitudinal extension (100a) of the hollow body (100), is designed to correspond to the inner cross-sectional area of the gas channel (200), so that a flow path through the exhaust gas sampling probe (1) extends from the probe input (201) through the at least one gap (106) via the at least one inlet opening (105) through the cavity (108) of the hollow body (100) via the at least one outlet opening (104) to the probe output (202).

2. Exhaust gas sampling probe (1) according to claim 1, characterized in that at least one sealing surface (109) is formed on a side of the second hollow body portion (102) facing away from the probe input (201), which sealing surface cooperates with a corresponding sealing surface of the inner surface of the gas channel (200) in the assembled state of the hollow body (100).

3. Exhaust gas sampling probe (1) according to claim 1 or 2, characterized in that the hollow body (100) is arranged and / or can be arranged detachably in the gas channel (200), the hollow body (100) preferably being connected to the inner wall of the gas channel (200).

4. Exhaust gas sampling probe (1) according to any of claims 1 to 3, characterized in that a tool holder (107) is provided on the side of the fluid-tight, sealed end face (103) of the hollow body (100) facing away from the outlet opening (104).

5. Exhaust gas sampling probe (1) according to any of claims 1 to 4, characterized in that the exhaust gas sampling probe (1) is designed in two or more parts, with the hollow body (100), a probe tip (3) which forms the first axial end of the exhaust gas sampling probe (1), and a probe body (4) which axially adjoins the probe tip (3).

6. Exhaust gas sampling probe (1) according to claim 5, characterized in that the hollow body (100) is arranged at least partly, preferably completely, within the probe tip (3).

7. Exhaust gas sampling probe (1) according to either of claims 5 or 6, characterized in that the probe tip (3) is designed as a coupling part (111) of a connecting coupling.

8. Exhaust gas sampling probe (1) according to any of claims 1 to 7, characterized in that at least one radially projecting support element (110) is provided on the outer wall of the exhaust gas sampling probe (1), preferably in the region of the probe tip (3).

9. Exhaust gas sampling probe (1) according to any of claims 1 to 8, characterized in that the radial cross-sectional area of the gap (106) substantially corresponds to the sum of the cross-sectional areas of the inlet openings (105) provided in the lateral surface of the hollow body (100), the radial cross-sectional area of the gap (106) preferably deviating by no more than a predetermined maximum deviation Emax from the sum of the cross-sectional areas of the inlet openings (105) provided in the lateral surface of the hollow body (100).

10. Exhaust gas sampling probe (1) according to claim 9, characterized in that the predetermined maximum deviation Emax is defined as a relative value of the sum of the cross-sectional areas of the inlet openings (105) provided in the lateral surface of the hollow body (100), the maximum deviation Emax corresponding to a relative value of 30%, or a relative value of 20%, or a relative value of 10%.

11. Exhaust gas sampling probe (1) according to any of the preceding claims, characterized in that each of the diameters of the inlet openings (105) provided in the lateral surface of the hollow body (100) are each smaller than a predetermined maximum diameter Dmax, the maximum diameter Dmax being in a value range of from 10 µm to 100 mm, or in a value range of from 100 µm to 10 mm, or in a value range of from 500 µm to 10 mm.

12. Exhaust gas sampling probe (1) according to any of the preceding claims, characterized in that an attachment unit (5) for attaching the exhaust gas sampling probe (1) to an exhaust gas pipe is provided on the outer wall of the exhaust gas sampling probe (1), preferably in the region of the probe output (202).

13. Use of an exhaust gas sampling probe (1) according to any of the preceding claims in an emission measuring apparatus (10), wherein an exhaust gas line (6) is joined to the emission measuring apparatus (10), and wherein the exhaust gas sampling probe (1) is connected or can be connected to the end of the exhaust gas line (6) facing away from the emission measuring apparatus (10).

14. Emission measuring apparatus (10) comprising at least one exhaust gas sampling probe (1) according to any of claims 1 to 12.