Pressure hose sensor

Abstract

A pressure hose sensor (1) comprising a hose body (2) which is closed at its end faces, wherein a pressure sensor (11) is arranged in the hose body (2), characterized in that the hose body (2) has at least one electrically conductive structure (8, 10) on its inner side (7, 9), which is structured such that when the pressure hose sensor (1) is disconnected, at least one electrical parameter of the conductive structure (8, 10) changes, wherein the electrical parameter can be detected by an evaluation unit (12), wherein the hose body (2) has a front side (5) and a rear side (6), wherein the front side (5) has a first conductive structure (8) and the rear side (6) has a second conductive structure (10), wherein the first conductive structure (8) and the second conductive structure (10) are electrically connected to one another,wherein the first conductive structure (8) and / or the second conductive structure (10) is formed as a meander structure (MS).,

Description

[0001] The invention relates to a pressure hose sensor according to the preamble of claim 1.

[0002] From DE 102 30 560 A1, it is known to integrate a pressure hose into a bumper of a motor vehicle. Such a pressure hose sensor can be used, for example, to activate active pedestrian protection systems. Such a pressure hose sensor comprises a hose body that is closed at its end faces, with a pressure sensor arranged within the hose body. If pressure is applied to the pressure hose at any point, the sensor detects this pressure increase. A disadvantage is that hose defects such as pinches, cuts, or leaks cannot be diagnosed.

[0003] From DE 197 31 178 C1 a hose line for flammable and non-flammable substances hazardous to water is known, comprising at least two hose layers, between which at least one electrical conductor is arranged, wherein the electrical conductor either has a continuous cross-section of less than 0.5 mm 2 and is made of a brittle material or has a cross-section of more than 0.5 mm 2 and is provided with predetermined breaking points at specific intervals, which break at a certain overstretching, at least in the longitudinal direction of the hose. It is further provided that the electrical conductor is a wire laid in sinusoidal loops with a small amplitude in at least one narrow zone arranged parallel to the hose's longitudinal axis.

[0004] EP 0 185 650 B1 discloses a hose, in particular a hydraulic hose, in whose wall a reinforcement is embedded. The reinforcement comprises at least one electrical measuring wire, the ends of which extend from the wall to electrical connections. The resistance of the measuring wire varies depending on the mechanical forces acting on it. It is further provided that the measuring wire runs helically within the wall or that the measuring wire runs in a zigzag manner around the circumference in the longitudinal direction of a hose section.

[0005] DE 199 36 076 A1 discloses a finite, flexible pressure hose, consisting of at least one first hose wall located between the outer and inner circumferences of the hose, in which at least one forward and one return electrical conductor is integrated over the effective length of the hose. The conductors are connected at the ends of the pressure hose to form an open or closed conductor loop. In this case, if the pressure hose is defective, e.g., a break at the connection points or a tear in the hose wall caused by overstretching, the current flow in the electrical conductor is interrupted.

[0006] A generic pressure hose sensor is known from DE 101 14 465 A1.

[0007] DE 691 01 771 T2 discloses a device for detecting a pinch and / or a tear of a resistive connection. The device consists of a tube having two electrically resistive inner surfaces arranged opposite each other and electrically insulated from each other. When the connection is pinched, the tube deforms, and the two surfaces come into electrical contact with each other.

[0008] A tubular switch is known from US 6 166 338 A.

[0009] WO 2003 / 042008 A2 relates to an airbag device for a vehicle, in particular for a motor vehicle with an airbag that is inflated with gas by a filling device. On the side of the airbag moving toward the occupant, there is a sensor element formed by intersecting sensor strips that detect pressure changes. The sensor strips respond to local pressure changes and transmit this sensed pressure change as a sensor signal to a control device. In response to this sensor signal, the amount of gas delivered by the filling device can be controlled, thus controlling the inflation characteristics of the airbag. Furthermore, a sensor for spatially and / or time-resolved force or pressure measurement is claimed.The sensor has resistance elements which form a matrix-like grid with rows and columns of spaced-apart contact areas of the resistance elements, wherein an electrical resistance at a contact area of ​​two resistance elements depends on the force or pressure load of the contact area. The invention is based on the technical problem of creating a pressure hose sensor which has an improved diagnosability of defects.

[0010] The solution to the technical problem results from the subject matter having the features of claim 1. Further advantageous embodiments of the invention result from the subclaims.

[0011] For this purpose, the pressure hose sensor comprises a hose body that is closed at its end faces, with a pressure sensor arranged in the hose body. The hose body has at least one electrically conductive structure on its inside that is structured in such a way that when the pressure hose is clamped off, at least one electrical parameter of the conductive structure changes, with the electrical parameter being detectable by an evaluation unit. In this case, clamping is understood to mean, in particular, a crushing of the hose body, in which the interior of the hose body is divided into two sub-chambers. In this case, a pressure change in the sub-chamber where the pressure sensor is not arranged would no longer be detected. Due to the change in the electrical parameter, the evaluation unit detects this clamping and can diagnose and signal this as a fault.The evaluation unit can be located inside or outside the hose body. The parameter is a resistance value. For example, a conductor structure can be applied to the inside of the hose body that shorts out when disconnected, allowing the change in resistance to be detected.

[0012] The hose body further has a front side and a back side, with the front side having a first conductive structure and the back side having a second conductive structure. If the hose body is a hollow cylinder, for example, the front and back sides are each half-cylinders. It can also be provided that the front and back sides are first coated, glued, or printed with the conductive structures as individual parts and then joined together to form the hose body. Alternatively, the conductive structures can also be incorporated during the manufacturing process of a seamless hose body or into the existing hose body.

[0013] Furthermore, the first conductive structure and the second conductive structure are electrically connected to one another, since changes in resistance can be measured very easily and reliably. Therefore, the first conductive structure is preferably connected to the second conductive structure via a resistor. The resistor is preferably at least one order of magnitude (a factor of 10) greater than the resistance value of the first and / or second conductive structure. This causes a very large change in resistance upon disconnection, which is very easily detectable. The resistor can, for example, be applied to the inside of a closure part of one end face. However, it is also possible to design the resistor as a discrete component.

[0014] Furthermore, the at least one conductive structure, the first conductive structure, and / or the second conductive structure is designed as a meandering structure. This has the advantage, particularly when detecting resistance changes, that a short circuit is ensured regardless of the exact orientation of the pinch. A further advantage is that meandering structures increase the probability that cuts in the hose body will lead to a severing of the conductive structure, so that cuts adjacent to pinches are also detected.

[0015] In one embodiment, the pressure sensor is arranged on an end face of the hose body, which preferably also serves to seal the end face.

[0016] In a further embodiment, the first conductive structure is designed as a meander structure and the second conductive structure as a full-surface structure. The full-surface structure ensures reliable short-circuiting (regardless of the orientation of the clamp), with the meander structure on the front side detecting incisions. It is assumed that after installation of the pressure hose sensor, the rear side of the hose body is largely protected, so that incisions are not to be feared there. However, incisions are conceivable that miss the meander structure and thus do not lead to a severance. Likewise, leaks cannot be detected, for example, at the front ends.

[0017] Therefore, in another embodiment, the pressure hose sensor is filled above normal pressure. If a cut or leak then occurs, this is detected and signaled by the pressure drop at the pressure sensor. The signaling is performed, for example, by a control unit that receives data from the pressure sensor and / or the evaluation unit. The diagnostics in the control unit should be sufficiently tolerant of temperature fluctuations and pressure fluctuations due to different altitudes. For this purpose, the control unit can, for example, receive temperature and altitude data from other sensors and perform appropriate compensation calculations so that pressure fluctuations due to changes in temperature or altitude do not lead to incorrect results.

[0018] In another embodiment, the pressure tube sensor is filled with a gas (other than air). Suitable gases include CO2 or xenon.

[0019] In another embodiment, the evaluation unit is integrated into the pressure sensor, allowing for a very compact design. In this case, the pressure sensor and the evaluation unit can transmit their data to an external control unit, which then performs the actual diagnosis and, if necessary, signaling. However, it is also possible to perform the entire diagnosis in the integrated pressure sensor, which then only outputs a diagnostic signal externally.

[0020] The invention is explained in more detail below using a preferred embodiment. The figures show: Fig. 1 a perspective view of a pressure hose sensor, Fig. 2 a cross-sectional view of the pressure hose sensor, Fig. 3 a schematic representation of an inside of a front side of the hose body, Fig. 4 a schematic longitudinal section through the pressure hose sensor, Fig. 5a a schematic equivalent circuit diagram of the pressure hose sensor in the normal state and Fig. 5b a schematic equivalent circuit diagram of the pressure hose sensor with a clamp.

[0021] The pressure hose sensor 1 comprises a hose body 2, which in the simplest case is designed as a hollow cylinder or, in further embodiments, as an application-specific shaped hollow body. The hose body 2 is sealed gas-tight at both its end faces by a base 3 and a cover 4. The hose body 2 has a front side 5 and a rear side 6, each designed as a half cylinder (see Fig. 2). A first conductive structure 8 is applied to the inner side 7 of the front side 5, and a second conductive structure 10 is applied to the inner side 9 of the rear side 6. The first conductive structure 8 is designed as a meander structure MS (see Fig. 3), whereby the structure can vary depending on the technology, for example, it may not have any curves, but rather sharp edges. The second conductive structure 10 is designed as a conductive surface that covers the inside 9 of the rear side 6 completely or at least almost completely. The first conductive structure 8 has a resistor R1 and the second conductive structure 10 has a resistor R2. The first conductive structure 8 and the second conductive structure 10 are connected via a resistor R D electrically connected to each other. Preferably, R D >> R1, R2. Preferably, R D be at least an order of magnitude larger. The resistance R Dis preferably arranged on an inner side of the base 3. A pressure sensor 11 and an evaluation unit 12 are arranged on the inner side of the cover 4. It should be noted that the pressure sensor 11 and evaluation unit 12 can be designed as an integrated unit. Furthermore, they can in principle also be designed such that they form the cover 4 itself. The pressure sensor 11 measures the pressure P1 inside the pressure hose sensor 1. The evaluation unit 12 determines the resulting resistance R or a comparable value such as the current in order to deduce the resulting resistance R. It should be noted that the pressure hose sensor 1 is filled with a pressure P1 that is greater than the normal ambient air pressure P OThe pressure sensor 11 and the evaluation unit 12 are connected via one or more data lines to a control unit 13, which, depending on a diagnosis, controls a display unit 14 to signal a status or error.

[0022] The pressure hose sensor 1 according to the invention can be monitored for functionality by means of the data from the pressure sensor 11 or the evaluation unit 12, whereby pinching, leaks or cuts can be diagnosed, which will be explained below.

[0023] In the normal state, the pressure sensor 11 measures the filling pressure P1 of the pressure hose sensor 1 and the evaluation unit 12 measures the resistance R, which results from the series connection of R1, R2 and R DIf a force F is then exerted from the outside on the front side 5, the pressure inside the pressure hose sensor 1 increases to P1*. This external force F is thus detected by the pressure sensor 11 and transmitted to the control unit 13, so that, for example, an active pedestrian protection system is activated. If, for whatever reason, the pressure hose sensor 1 is disconnected, a pressure change in the part of the pressure hose sensor 1 that is disconnected from the pressure sensor 1 cannot be detected by the pressure sensor 11. However, the disconnection leads to the first conductive structure 8 and the second conductive structure 10 touching each other and the resistance R D short-circuit, which in Fig.5b is shown schematically. The resulting resistance R is then smaller than the series connection of R1 and R2 (neglecting contact resistances at the clamp). The evaluation unit 12 can accordingly transmit the resulting resistance R to the control unit 13, which can then signal the defect. A cut in the pressure hose sensor 1 causes the pressure P1 to decrease and approach the external ambient pressure P O This allows defects caused by leaks or cuts to be diagnosed and also signaled by control unit 13.

Claims

[1] Pressure hose sensor (1), comprising a hose body (2) which is closed at its end faces, wherein a pressure sensor (11) is arranged in the hose body (2), characterized byin that the hose body (2) has on its inner side (7, 9) at least one electrically conductive structure (8, 10) which is structured in such a way that when the pressure hose sensor (1) is disconnected at least one electrical parameter of the conductive structure (8, 10) changes, wherein the electrical parameter can be detected by an evaluation unit (12), wherein the hose body (2) has a front side (5) and a back side (6), wherein the front side (5) has a first conductive structure (8) and the back side (6) has a second conductive structure (10), wherein the first conductive structure (8) and the second conductive structure (10) are electrically connected to one another, wherein the first conductive structure (8) and / or the second conductive structure (10) is designed as a meander structure (MS). [2] Pressure hose sensor (1) according to claim 1, characterized by that the pressure sensor (11) is arranged on an end face of the hose body (2). [3] Pressure hose sensor (1) according to claim 1 or 2, characterized by that the first conductive structure (8) and the second conductive structure (10) are connected via a resistor (R D ) are connected to each other. [4] Pressure hose sensor (1) according to one of the preceding claims, characterized by that the first conductive structure (8) is designed as a meander structure (MS) and the second conductive structure (10) is designed as a full-surface structure. [5] Pressure hose sensor (1) according to one of the preceding claims, characterized by that the pressure hose sensor (1) is above the normal pressure (P O ) is filled. [6] Pressure hose sensor (1) according to claim 5, characterized by that the pressure hose sensor (1) is filled with a filling gas. [7] Pressure hose sensor (1) according to one of the preceding claims, characterized by that the evaluation unit (12) is integrated into the pressure sensor (11).

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