EP1721135A1 - Force-sensing device - Google Patents

Force-sensing device

Info

Publication number
EP1721135A1
EP1721135A1 EP05707831A EP05707831A EP1721135A1 EP 1721135 A1 EP1721135 A1 EP 1721135A1 EP 05707831 A EP05707831 A EP 05707831A EP 05707831 A EP05707831 A EP 05707831A EP 1721135 A1 EP1721135 A1 EP 1721135A1
Authority
EP
European Patent Office
Prior art keywords
measuring device
force measuring
rigid housing
housing
spring elements
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05707831A
Other languages
German (de)
French (fr)
Inventor
Oliver Menke
Franz Stadler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Continental Automotive GmbH
Original Assignee
Siemens AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Publication of EP1721135A1 publication Critical patent/EP1721135A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
    • G01G19/40—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight
    • G01G19/413—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means
    • G01G19/414—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means using electronic computing means only
    • G01G19/4142—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means using electronic computing means only for controlling activation of safety devices, e.g. airbag systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
    • G01G19/40—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight
    • G01G19/413—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means
    • G01G19/414—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means using electronic computing means only
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
    • G01G19/40—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight

Definitions

  • the invention relates to a force measuring device.
  • the force measuring device has a one-piece housing made of metal, with upper and lower rigid housing parts which are resiliently movable relative to one another.
  • a deflection sensor is mounted between the two rigid housing parts, which can detect the deflection of the two rigid housing parts relative to one another and can transmit this as an electrical signal.
  • the housing of the force measuring device can be made in one piece and made of spring metal, with rigid housing parts (220) and (222) and spring means (232, 234) that hold the rigid housing parts (220, 222) (FIG. 4 and column 8, rows) 18 to 27).
  • a deflection sensor is arranged between the two rigid housing parts (220, 222), for example an inductive deflection sensor (190, 192, 194, 196, 198) (FIG. 3), which detects a deflection of the rigid housing parts (220, 222) and into one Can convert measurement signal that provides information about the force acting on the force measuring device.
  • German published patent application DE 101 45 370 A1 discloses a similar force measuring device made of a one-piece metal housing (FIG. 4b and column 6, paragraph [0059]), but with a different sensor principle.
  • the known force measuring devices In order to be able to use them in a motor vehicle, the known force measuring devices have to be made very small, on the one hand, to take into account the limited installation space between a vehicle seat and the vehicle chassis, and, on the other hand, have to be extremely dimensionally stable over the entire service life of a vehicle, usually at least 15 years to avoid systematic incorrect measurements of the deflection sensor over time.
  • these two requirements for the known force measuring devices are contradictory and seem to be incompatible with one another:
  • a very solid and rather large housing speaks for the force measuring device for a permanently dimensionally stable housing that can withstand the very heavy weight loads of up to 1.2 t during operation of a motor vehicle ,
  • a small installation space rather requires a filigree, small housing.
  • the object of the present invention is to create a force measuring device with a permanently dimensionally stable, hysteresis-free housing, which is at the same time very small and can be easily manufactured.
  • the object is achieved by a force measuring device according to claim 1.
  • the force measuring device comprises a one-piece housing made of metal.
  • the housing comprises an upper rigid housing part and a lower rigid housing part which are connected to one another via U-shaped spring elements and which can be moved resiliently against one another under the action of a force along an axis of movement.
  • the spring elements are arranged symmetrically with respect to one another with respect to a cut surface parallel to the movement axis.
  • a deflection sensor for detecting the relative movement of the two rigid housing parts relative to one another is mounted between the upper and lower rigid housing parts.
  • the housing is manufactured using metal injection molding (MIM) technology.
  • MIM metal injection molding
  • MIM technology also known as powder metal injection molding, mixes and granulates fine metal powder with primary binders, creating a feedstock.
  • the feedstock is melted in an injection molding machine and injected into the molded part in a mold. After cooling, the components are removed as so-called green compacts.
  • the binder is then removed from the green compacts in an oven expelled.
  • the binderless components are now called brown parts and are then sintered in a high-temperature furnace.
  • MIM technology combines the freedom of shape of plastic injection molding with powder metallurgy.
  • the MIM process therefore offers the possibility of cost-effectively producing large quantities of highly integrated metal parts with complex geometries and with high precision.
  • the one-piece design of the housing according to the invention makes it possible to avoid previously complex joining processes between different components of the housing, as a result of which - as a result of the reduced number of joining edges - hysteresis phenomena in the force measuring device according to the invention can be considerably reduced.
  • FIG. 1 shows an exemplary embodiment for a force measuring device (1) according to the invention in cross section
  • FIG. 2 shows the force measuring device according to FIG. 1 in a perspective view
  • 3 shows the force measuring device according to FIG. 1 in a top view
  • FIG. 4 shows the force measuring device from FIG. 1 in a cross-sectional illustration along the sectional area AA.
  • Figure 1 shows an advantageous development of a power device 1 according to the invention, consisting of a one-piece housing 2, which is made in metal injection molding (MIM) technology.
  • the housing has an upper housing part 25 and a lower housing part 26, which are rigid in comparison to the U-shaped spring elements 21 and 22 connecting these two housing parts 25, 26, so that these two rigid housing parts 25 and 26 are indeed one another can move towards or away from each other under the influence of a weight, but ideally do not deform themselves.
  • MIM metal injection molding
  • a deflection sensor 6 is attached, which can detect a relative movement of the two housing parts 25, 26 relative to one another and convert it into an electrical signal, which is led to evaluation electronics via a plug connection (not shown) via a plug 5, or is further processed in an evaluation electronics within the connector 5.
  • This signal is fed to an occupant protection device, also not shown, and is available there as information about the weight acting on the force measuring device 1, on the basis of which an occupant restraint device is triggered in an adapted manner, if necessary.
  • each of the spring elements tapers continuously starting from the upper rigid housing part 25 until it reaches a minimum wall thickness d at the beginning of the bend to the U-loop. From this point, the wall thickness increases again around the apex of the U-loop, decreases again after the loop winding and remains constant until the transition into the lower rigid housing part 26. Since the sectional area AA represents a plane of symmetry of the spring element, the course of the wall thickness is d along the spring element is equal to that of the spring element 22.
  • the housing 1 shown as two integral components behind each of the two spring loops 21 and 22 shown each has a fastening tab 4, by means of which the force measuring device 1 is connected to the vehicle chassis by means of two screws 7.
  • Other fastening means could be used instead of screws, for example rivets or the like.
  • FIG. 2 shows the force measuring device of Figure 1 in perspective. It can be seen that again a further pair of U-shaped spring elements 24 and 25 are arranged symmetrically around the two rigid housing parts 25 and 26 behind the two fastening means 4 with the associated screws 1.
  • the four spring loops 21, 22, 23, 24 shown can be made so narrow that the fastening points of the force measuring device 1 are arranged within the same base area can be taken up by the entire housing 2 including spring elements 21, 22, 23 and 24.
  • This base area is shown again in plan view in FIG. 4.
  • FIG. 4 shows a cross section through the housing 2 of the force measuring device 1 along the section line AA in FIG were.
  • each of the two overload protection elements 8 and 9 are firmly connected to the upper rigid housing part 25, for example by means of a screw connection.
  • the diameter of each of the two overload protection elements 8 and 9 increases in steps and is spaced from the lower rigid housing part 26 by an approximately constant narrow air gap.
  • the two overload protection elements 8 and 9 emerge from the housing 2 as soon as a force acts on the force introduction means 3 in the direction of the lower rigid housing part 26.
  • a further deflection of the two rigid housing parts 25 and 26 to one another, with a further increased force effect, is only prevented when the two overload protection elements 8 and 9 have emerged from the housing 2 to such an extent that they encounter resistance from the vehicle chassis.
  • the two rigid housing parts 25 and 26 are deflected relative to one another until the gap between the lower rigid housing part 26 and the step in each of the two overload protection elements is closed.

Abstract

The invention relates to a force sensing device (1) comprising a single-component metal housing (2). Said housing (2) comprises an upper rigid housing part (25) and a lower rigid housing part (26) that are interconnected by means of U-shaped spring elements (21, 22, 23, 24) and can be elastically displaced along a displacement axis (60) in relation to each other by the action of a force. The spring elements (21, 22, 23, 24) are symmetrically arranged in relation to a section (AA) parallel to the displacement axis (60). A deflection sensor (6) is arranged between the upper and lower rigid housing parts (25, 26), for detecting the relative displacement of the two rigid housing parts (25, 26) in relation to each other. According to the invention, the housing (2) is produced using metal injection molding (MIM) technology.

Description

Beschreibungdescription
KraftmessvorrichtungForce measuring device
Die Erfindung betrifft eine Kraftmessvorrichtung. Die Kraftmessvorrichtung weist ein einstückig gefertigtes Gehäuse aus Metall auf, mit oberen und unteren starren Gehäuseteilen, die zueinander federnd bewegbar sind. Zwischen die beiden starren Gehäuseteile ist ein Auslenksensor angebracht, der die Aus- lenkung der beiden starren Gehäuseteile zueinander erfassen und als elektrisches Signal weitergeben kann.The invention relates to a force measuring device. The force measuring device has a one-piece housing made of metal, with upper and lower rigid housing parts which are resiliently movable relative to one another. A deflection sensor is mounted between the two rigid housing parts, which can detect the deflection of the two rigid housing parts relative to one another and can transmit this as an electrical signal.
Im Bereich des Insassenschutzes in Kraftfahrzeugen wird es in den letzten Jahren immer wichtiger die Auslösung von Insas- senrückhaltemitteln, beispielsweise Frontairbags, Seitenair- bags, Knieairbags, Vorhangairbags, etc. an gegebenenfalls im Entfaltungsbereich der Insassenrückhaltemittel befindliche Fahrzeuginsassen anzupassen oder sogar gänzlich zu unterdrücken, um einerseits spätere Reparaturkosten nach einer unnö- tigen Auslösung, beispielsweise bei einem nicht belegtenIn the field of occupant protection in motor vehicles, it has become increasingly important in recent years to adapt or even completely suppress the triggering of occupant restraint devices, for example front airbags, side airbags, knee airbags, curtain airbags, etc., to vehicle occupants possibly located in the deployment area of the occupant restraint means on the one hand, later repair costs after an unnecessary triggering, for example in the case of an unused
Fahrzeugsitz zu sparen, und andererseits um bestimmte Personengruppen nicht durch ein ungeeignetes Auslöseverhalten des Insassenrückhaltemittels zusätzlich zu gefährden, beispielsweise Kinder oder sehr kleine Erwachsene. Es ist also nicht nur wichtig, die Anwesenheit einer Person auf einem Kraftfahrzeugsitz festzustellen, sondern darüber hinaus sogar klassifizierende Eigenschaften der Person, beispielsweise das Körpergewicht. Zu nennen ist in diesem Zusammenhang die Crash-Norm FMVSS208, deren Einhaltung immer mehr von Fahr- zeugherstellern gefordert wird und die eine Klassifizierung einer Person nach einem Gewicht festschreibt, um im Falle einer Kollision die Ansteuerung eines Insassenrückhaltemittels ggf. in bekannter Weise an die erkannte Person anzupassen.To save vehicle seat, and on the other hand in order not to further endanger certain groups of people by inappropriate triggering behavior of the occupant restraint, for example children or very small adults. It is therefore not only important to determine the presence of a person in a motor vehicle seat, but also to have classifying properties of the person, for example the body weight. Worth mentioning in this context is the crash standard FMVSS208, compliance with which vehicle manufacturers are increasingly demanding and which stipulates the classification of a person by weight so that, in the event of a collision, the activation of an occupant restraint may be recognized in a known manner Adapt person.
Aus der Druckschrift DE 100 04 484 AI ist es bekannt, zum Erkennen des Gewichts einer Person auf einem Kraftfahrzeugsitz Kraftmessvorrichtungen zwischen dem Fahrzeugsitz und dem Fahrzeugchassis anzuordnen. Dabei kann das Gehäuse der Kraftmessvorrichtung einstückig und aus Federmetall gefertigt sein, mit starren Gehäuseteilen (220) und (222) und Federmitteln (232, 234), die die starren Gehäuseteile (220, 222) (Fi- gur 4 und Spalte 8, Zeilen 18 bis 27) verbinden. Zwischen den beiden starren Gehäuseteilen (220, 222) ist ein Auslenksensor angeordnet, beispielsweise ein induktiver Auslenksensor (190, 192, 194, 196, 198) (Figur 3), der eine Auslenkung der starren Gehäuseteile (220, 222) feststellen und in ein Messsignal umwandeln kann, das Aufschluss über die auf die Kraftmessvorrichtung wirkende Kraft gibt.From the document DE 100 04 484 AI it is known to detect the weight of a person on a motor vehicle seat force measuring devices between the vehicle seat and Arrange vehicle chassis. The housing of the force measuring device can be made in one piece and made of spring metal, with rigid housing parts (220) and (222) and spring means (232, 234) that hold the rigid housing parts (220, 222) (FIG. 4 and column 8, rows) 18 to 27). A deflection sensor is arranged between the two rigid housing parts (220, 222), for example an inductive deflection sensor (190, 192, 194, 196, 198) (FIG. 3), which detects a deflection of the rigid housing parts (220, 222) and into one Can convert measurement signal that provides information about the force acting on the force measuring device.
Die deutsche Offenlegungsschrift DE 101 45 370 AI offenbart eine ähnliche Kraftmessvorrichtung aus einem einstückigen Me- tallgehäuse (Figur 4b und Spalte 6, Absatz [0059]), allerdings mit einem unterschiedlichen Sensorprinzip.German published patent application DE 101 45 370 A1 discloses a similar force measuring device made of a one-piece metal housing (FIG. 4b and column 6, paragraph [0059]), but with a different sensor principle.
Die bekannten Kraftmessvorrichtungen müssen, um sie nutzbringend in einem Kraftfahrzeug einsetzen zu können, zum einen sehr klein gefertigt werden, um den beschränkten Bauraum zwischen einem Fahrzeugsitz und dem Fahrzeugchassis Rechnung zu tragen, und zum anderen äußerst formstabil über die gesamte Lebensdauer eines Fahrzeugs sein, üblicherweise mindestens 15 Jahre, um systematische Fehlmessungen des Auslenksensors im Laufe der Zeit möglichst zu vermeiden. Diese beiden Anforderungen an die bekannten Kraftmessvorrichtungen sind jedoch widerstreitend und scheinen unvereinbar miteinander: Für ein dauerhaft formstabiles Gehäuse, das den im Betrieb eines Kraftfahrzeugs sehr großen Gewichtsbelastungen von bis zu 1,2 t standhält, spricht ein sehr massives und eher großes Gehäuse für die Kraftmessvorrichtung. Ein kleiner Bauraum erfordert eher ein filigranes, kleines Gehäuse.In order to be able to use them in a motor vehicle, the known force measuring devices have to be made very small, on the one hand, to take into account the limited installation space between a vehicle seat and the vehicle chassis, and, on the other hand, have to be extremely dimensionally stable over the entire service life of a vehicle, usually at least 15 years to avoid systematic incorrect measurements of the deflection sensor over time. However, these two requirements for the known force measuring devices are contradictory and seem to be incompatible with one another: A very solid and rather large housing speaks for the force measuring device for a permanently dimensionally stable housing that can withstand the very heavy weight loads of up to 1.2 t during operation of a motor vehicle , A small installation space rather requires a filigree, small housing.
Aufgabe der vorliegenden Erfindung ist es, eine Kraftmessvor- richtung mit einem dauerhaft formstabilen, möglichst hysteresefreien Gehäuse zu schaffen, das gleichzeitig sehr klein ist und einfach gefertigt werden kann. Die Aufgabe wird gelöst durch eine Kraftmessvorrichtung gemäß Anspruch 1.The object of the present invention is to create a force measuring device with a permanently dimensionally stable, hysteresis-free housing, which is at the same time very small and can be easily manufactured. The object is achieved by a force measuring device according to claim 1.
Vorteilhafte Ausführungsformen sind in den Unteransprüchen angegeben, wobei jede beliebige sinnvolle Kombination von Merkmalen der Unteransprüche mit dem Hauptanspruch unter Schutz gestellt werden sollen.Advantageous embodiments are specified in the subclaims, any meaningful combination of features of the subclaims with the main claim to be protected.
Die erfindungsgemäße Kraftmessvorrichtung umfasst ein einstückiges Gehäuse aus Metall. Das Gehäuse umfasst einen oberen starren Gehäuseteil und einen unteren starren Gehäuseteil, die über U-förmige Federelemente miteinander verbunden sind und die unter Einwirken einer Kraft entlang einer Bewegungs- achse federnd gegeneinander bewegbar sind. Die Federelemente sind bezüglich einer Schnittfläche parallel zur Bewegungsachse symmetrisch zueinander angeordnet. Zwischen den oberen und unteren starren Gehäuseteilen ist ein Auslenksensor zur Erfassung der Relativbewegung der beiden starren Gehäuseteile zueinander angebracht. Erfindungsgemäß ist das Gehäuse in Metal Injection Molding (MIM) Technologie gefertigt.The force measuring device according to the invention comprises a one-piece housing made of metal. The housing comprises an upper rigid housing part and a lower rigid housing part which are connected to one another via U-shaped spring elements and which can be moved resiliently against one another under the action of a force along an axis of movement. The spring elements are arranged symmetrically with respect to one another with respect to a cut surface parallel to the movement axis. A deflection sensor for detecting the relative movement of the two rigid housing parts relative to one another is mounted between the upper and lower rigid housing parts. According to the invention, the housing is manufactured using metal injection molding (MIM) technology.
Die Verwendung der MIM Technologie ist bislang nur aus anderen technischen Bereichen bekannt, hingewiesen sei hier bei- spielsweise auf eine Veröffentlichung der Fa. Hans Schweiger GmbH, die am 03.März.2004 auf der Internetseite http: //www. formapulvis . com/Index. htm aufrufbar war, in der der MIM Herstellungsprozess für verschiedene Anwendungsgebiete beschrieben wird.So far, the use of MIM technology is only known from other technical areas, for example, a publication by Hans Schweiger GmbH, which was published on March 03, 2004 on the website http: // www. formapulvis. com / index. htm was available, in which the MIM manufacturing process is described for different areas of application.
Bei der MIM Technik, auch bekannt als Pulvermetallspritzgießen, wird feines Metallpulver mit primären Bindern gemischt und granuliert, es entsteht ein sogenannter Feedstock. Der Feedstock wird in einer Spritzgießmaschine aufgeschmolzen und in einem Werkzeug zum Formteil gespritzt. Nach der Abkühlung werden die Bauteile als sogenannte Grünlinge entnommen. Anschließend wird der Binder in einem Ofen aus den Grünlingen ausgetrieben. Die binderlosen Bauteile heißen jetzt Braunlinge und werden anschließend in einem Hochtemperaturofen gesintert.MIM technology, also known as powder metal injection molding, mixes and granulates fine metal powder with primary binders, creating a feedstock. The feedstock is melted in an injection molding machine and injected into the molded part in a mold. After cooling, the components are removed as so-called green compacts. The binder is then removed from the green compacts in an oven expelled. The binderless components are now called brown parts and are then sintered in a high-temperature furnace.
Die MIM Technik verbindet dabei die Formgebungsfreiheit des KunststoffSpritzgießens mit der Pulvermetallurgie. Das MIM- Verfahren bietet deshalb die Möglichkeit, hochintegrierte Metallteile mit komplexen Geometrien und in hoher Präzision in großen Stückzahlen kostengünstig herzustellen.MIM technology combines the freedom of shape of plastic injection molding with powder metallurgy. The MIM process therefore offers the possibility of cost-effectively producing large quantities of highly integrated metal parts with complex geometries and with high precision.
Mit dem MIM-Verfahren ist es deshalb möglich, Gehäusewandungen mit sehr exakte Dicken herzustellen und somit sehr exakt berechnete Form- und Dickenverläufe in einem Metallgehäuse einer erfindungsgemäßen Kraftmessvorrichtung zu erreichen. Dadurch kann ein sehr kleines federndes Gehäuse hergestellt werden, so dass dennoch bei einer geforderten maximalen Nennbelastung von beispielsweise 150 kg auf die Kraftmessvorrichtungen eine maximale innere Spannung von 350 Newton/mm2 an keiner Stelle im Gehäuse überschritten wird und gleichzeitig eine Auslenkung der starren Gehäuseteile zueinander von mindestens 1 μm pro kg auflastenden Gewichts erreicht wird.With the MIM method it is therefore possible to produce housing walls with very exact thicknesses and thus to achieve very precisely calculated shape and thickness profiles in a metal housing of a force measuring device according to the invention. As a result, a very small resilient housing can be produced, so that with a required maximum nominal load of, for example, 150 kg on the force measuring devices, a maximum internal tension of 350 Newton / mm 2 is not exceeded at any point in the housing and at the same time a deflection of the rigid housing parts relative to one another of at least 1 μm per kg of load weight.
Außerdem ist es durch die Einstückigkeit des erfindungsgemäßen Gehäuses möglich, bislang aufwändige Fügeprozesse zwi- sehen verschiedenen Bestandteilen des Gehäuses zu vermeiden, wodurch - in Folge der reduzierten Anzahl von Fügekanten - Hysterese-Erscheinungen bei der erfindungsgemäßen Kraftmessvorrichtung erheblich reduziert werden können.In addition, the one-piece design of the housing according to the invention makes it possible to avoid previously complex joining processes between different components of the housing, as a result of which - as a result of the reduced number of joining edges - hysteresis phenomena in the force measuring device according to the invention can be considerably reduced.
Vorteilhafte A sführungsformen von erfindungsgemäßen Vorrichtungen sind in der nachfolgenden Figurenbeschreibung enthalten. Es zeigen:Advantageous embodiments of devices according to the invention are contained in the following description of the figures. Show it:
Figur 1 ein Ausführungsbeispiel für eine erfindungsgemäße Kraftmessvorrichtung (1) im Querschnitt,FIG. 1 shows an exemplary embodiment for a force measuring device (1) according to the invention in cross section,
Figur 2 die Kraftmessvorrichtung gemäß Figur 1 in perspektivischer Darstellung, Figur 3 die Kraftmessvorrichtung gemäß Figur 1 in Draufsicht und Figur 4 die Kraftmessvorrichtung aus Figur 1 in Querschnittsdarstellung entlang der Schnittfläche A-A.FIG. 2 shows the force measuring device according to FIG. 1 in a perspective view, 3 shows the force measuring device according to FIG. 1 in a top view and FIG. 4 shows the force measuring device from FIG. 1 in a cross-sectional illustration along the sectional area AA.
Figur 1 zeigt eine vorteilhafte Weiterbildung einer erfindungsgemäßen Kraftvorrichtung 1, bestehend aus einem einstückigen Gehäuse 2, das in Metal Injection Molding (MIM) Technologie gefertigt ist. Das Gehäuse weist einen oberen Gehäu- seteil 25 und einen unteren Gehäuseteil 26 auf, die im Vergleich zu den diese beiden Gehäuseteile 25, 26 verbindenden U-förmigen Federelementen 21 und 22 starr ausgebildet sind, so dass diese beiden starren Gehäuseteile 25 und 26 sich zwar unter Einwirken einer Gewichtskraft zueinander hin- oder von- einander wegbewegen können, sich jedoch selbst idealerweise nicht verformen. Zwischen den beiden starren Gehäuseteilen 25 und 26 ist ein Auslenksensor 6 angebracht, der eine Relativbewegung der beiden Gehäuseteile 25, 26 zueinander erfassen und in ein elektrisches Signal wandeln kann, das über eine nicht gezeigte Kabelverbindung über einen Stecker 5 zu einer Auswerteelektronik geführt wird, oder in einer Auswerteelektronik innerhalb des Steckers 5 weiterverarbeitet wird. Dieses Signal wird einer ebenfalls nicht gezeigten Insassenschutzvorrichtung zugeführt und steht dort als Information über das auf die Kraftmessvorrichtung 1 wirkende Gewicht zur Verfügung, aufgrund derer ein Insassenrückhaltemittel gegebenenfalls adaptiert ausgelöst wird.Figure 1 shows an advantageous development of a power device 1 according to the invention, consisting of a one-piece housing 2, which is made in metal injection molding (MIM) technology. The housing has an upper housing part 25 and a lower housing part 26, which are rigid in comparison to the U-shaped spring elements 21 and 22 connecting these two housing parts 25, 26, so that these two rigid housing parts 25 and 26 are indeed one another can move towards or away from each other under the influence of a weight, but ideally do not deform themselves. Between the two rigid housing parts 25 and 26, a deflection sensor 6 is attached, which can detect a relative movement of the two housing parts 25, 26 relative to one another and convert it into an electrical signal, which is led to evaluation electronics via a plug connection (not shown) via a plug 5, or is further processed in an evaluation electronics within the connector 5. This signal is fed to an occupant protection device, also not shown, and is available there as information about the weight acting on the force measuring device 1, on the basis of which an occupant restraint device is triggered in an adapted manner, if necessary.
Im Sinne der eingangs erwähnten wünschenswerten geringen me- chanischen Spannungen im Gehäuse 22, selbst unter Einwirken einer Kraft, die über ein Krafteinleitmittel 3 von einem Kraftfahrzeugsitz auf das obere starre Gehäuseteil 25 und somit auf die Kraftmessvorrichtung 1 aufgebracht wird, bilden die Schenkel der beiden Federelemente 22 und 21 einen spitz- ten Winkel Ct. Weiterhin im Sinne einer weitgehend gleichmäßigen Spannungsverteilung im ganzen Gehäuse 2 der Kraftmessvorrichtung 1 verjüngt sich jedes der Federelemente ausgehend von dem oberen starren Gehäuseteil 25 kontinuierlich bis es beim Beginn der Biegung zur U-Schlaufe eine geringste Wanddicke d erreicht. Ab diesem Punkt nimmt die Wandstärke um den Scheitelpunkt der U-Schlaufe wieder zu, verringert sich nach der Schlaufenwindung wieder und bleibt konstant bis zum Übergang in das untere starre Gehäuseteil 26. Da die Schnittfläche AA eine Symmetrieebene des Federelements darstellt, ist der Verlauf der Wanddicke d entlang des Federelements gleich dem des Federelements 22.In the sense of the desirable low mechanical tensions in the housing 22 mentioned at the outset, even under the action of a force which is applied to the upper rigid housing part 25 and thus to the force measuring device 1 from a motor vehicle seat via a force introduction means 3, form the legs of the two spring elements 22 and 21 an acute angle Ct. Furthermore, in the sense of a largely uniform tension distribution in the entire housing 2 of the force measuring device 1, each of the spring elements tapers continuously starting from the upper rigid housing part 25 until it reaches a minimum wall thickness d at the beginning of the bend to the U-loop. From this point, the wall thickness increases again around the apex of the U-loop, decreases again after the loop winding and remains constant until the transition into the lower rigid housing part 26. Since the sectional area AA represents a plane of symmetry of the spring element, the course of the wall thickness is d along the spring element is equal to that of the spring element 22.
Weiterhin weist das dargestellte Gehäuse 1 als zwei integrale Bestandteile hinter jeder der beiden dargestellten Federschlaufen 21 und 22 jeweils eine Befestigungslasche 4 auf, mit Hilfe derer die Kraftmessvorrichtung 1 über zwei Schrauben 7 mit dem Fahrzeugchassis verbunden sind. An der Stelle von Schrauben könnten auch andere Befestigungsmittel verwen- det werden, beispielsweise Nieten oder ähnliches.Furthermore, the housing 1 shown as two integral components behind each of the two spring loops 21 and 22 shown each has a fastening tab 4, by means of which the force measuring device 1 is connected to the vehicle chassis by means of two screws 7. Other fastening means could be used instead of screws, for example rivets or the like.
Figur 2 zeigt die Kraftmessvorrichtung der Figur 1 in perspektivischer Darstellung. Man erkennt, dass wiederum hinter den beiden Befestigungsmitteln 4 mit den zugehörigen Schrau- ben 1 ein weiteres Paar von U-förmigen Federelementen 24 und 25 symmetrisch um die beiden starren Gehäuseteile 25 und 26 angeordnet sind. Anhand dieser Darstellung ist besonders deutlich erkennbar, wie mit Hilfe der Möglichkeit zu einer sehr filigranen Ausgestaltung des Gehäuses 2 die vier darge- stellten Federschlaufen 21, 22, 23, 24 so schmal gefertigt sein können, dass die Befestigungspunkte der Kraftmessvorrichtung 1 innerhalb derselben Grundfläche angeordnet sein können, die vom gesamten Gehäuse 2 samt Federelementen 21, 22, 23 und 24 eingenommen wird. Diese Grundfläche wird in Fi- gur 4 nochmals in Draufsicht gezeigt. Figur 4 zeigt einen Querschnitt durch das Gehäuse 2 der Kraftmessvorrichtung 1 entlang der Schnittlinie A-A der Figur 1. Anhand dieser Querschnittsdarstellung soll die Wirkungsweise von zusätzlichen Überlastschutzelementen 8, 9 erläutert werden, die bereits in den beiden Figuren 2 und 3 in Draufsicht des Gehäuses 2 dargestellt waren. Die beiden Überlastschutzelemente 8. 9 sind mit dem oberen starren Gehäuseteil 25 fest verbunden, beispielsweise mittels einer Schraubverbindung. In Richtung zum unteren starren Gehäuseteil 26 hin nimmt der Durchmesser jeder der beiden Überlastschutzelemente 8 und 9 stufenförmig zu und ist zum unteren starren Gehäuseteil 26 hin durch einen etwa gleichbleibenden schmalen Luftspalt beabstandet.Figure 2 shows the force measuring device of Figure 1 in perspective. It can be seen that again a further pair of U-shaped spring elements 24 and 25 are arranged symmetrically around the two rigid housing parts 25 and 26 behind the two fastening means 4 with the associated screws 1. On the basis of this illustration it can be seen particularly clearly how, with the aid of the possibility of a very delicate design of the housing 2, the four spring loops 21, 22, 23, 24 shown can be made so narrow that the fastening points of the force measuring device 1 are arranged within the same base area can be taken up by the entire housing 2 including spring elements 21, 22, 23 and 24. This base area is shown again in plan view in FIG. 4. FIG. 4 shows a cross section through the housing 2 of the force measuring device 1 along the section line AA in FIG were. The two overload protection elements 8. 9 are firmly connected to the upper rigid housing part 25, for example by means of a screw connection. In the direction of the lower rigid housing part 26, the diameter of each of the two overload protection elements 8 and 9 increases in steps and is spaced from the lower rigid housing part 26 by an approximately constant narrow air gap.
Auf diese Weise treten die beiden Überlastschutzelemente 8 und 9 aus dem Gehäuse 2 heraus sobald eine Kraft über das Krafteinleitmittel 3 in Richtung des unteren starren Gehäuseteils 26 einwirkt. Eine weitere Auslenkung der beiden starren Gehäuseteile 25 und 26 zueinander, bei einer weiter erhöhten Kraftwirkung wird erst dann verhindert, wenn die beiden Überlastschutzelemente 8 und 9 so weit aus dem Gehäuse 2 hervorgetreten sind, dass sie auf einen Widerstand durch das Fahrzeugchassis treffen. Bei einer Krafteinwirkung in umgekehrter Richtung erfolgt eine Auslenkung der beiden starren Gehäuse- teile 25 und 26 zueinander solange bis der Spalt zwischen dem unteren starren Gehäuseteil 26 und der Stufe in jedem der beiden Überlastschutzelemente geschlossen ist. In this way, the two overload protection elements 8 and 9 emerge from the housing 2 as soon as a force acts on the force introduction means 3 in the direction of the lower rigid housing part 26. A further deflection of the two rigid housing parts 25 and 26 to one another, with a further increased force effect, is only prevented when the two overload protection elements 8 and 9 have emerged from the housing 2 to such an extent that they encounter resistance from the vehicle chassis. When force is applied in the opposite direction, the two rigid housing parts 25 and 26 are deflected relative to one another until the gap between the lower rigid housing part 26 and the step in each of the two overload protection elements is closed.

Claims

Patentansprüche claims
1. Kraftmessvorrichtung (1) - mit einem einstückigen Gehäuse aus Metall, bestehend aus einem oberen starren Gehäuseteil (25) und einem unteren starren Gehäuseteil (26) , die über U-förmige Federelemente (21, 22, 23, 24) miteinander verbunden sind und die unter Einwirken einer Kraft entlang einer Bewegungsachse (60) federnd gegeneinander bewegbar sind, wobei die Federele- mente (21, 22, 23, 24) bezüglich einer Schnittfläche (AA) parallel zur Bewegungsachse (60) symmetrisch zueinander angeordnet sind, und - mit einem Auslenksensor (6) zwischen den oberen und unteren starren Gehäuseteilen (25, 26) zur Erfassung deren Re- lativbewegung zueinander, dadurch gekennzeichnet, dass das Gehäuse (2) in Metal Injection Molding (MIM) Technologie gefertigt ist.1. Force measuring device (1) - with a one-piece housing made of metal, consisting of an upper rigid housing part (25) and a lower rigid housing part (26), which are connected to one another via U-shaped spring elements (21, 22, 23, 24) and which can be moved resiliently against one another under the action of a force along a movement axis (60), the spring elements (21, 22, 23, 24) being arranged symmetrically with respect to one another with respect to a cutting surface (AA) parallel to the movement axis (60), and - with a deflection sensor (6) between the upper and lower rigid housing parts (25, 26) for detecting their relative movement to one another, characterized in that the housing (2) is manufactured using metal injection molding (MIM) technology.
2. Kraftmessvorrichtung (1) nach Anspruch 1, dadurch gekenn- zeichnet, dass die beiden Schenkel der Federelemente (21, 22, 23, 24) jeweils einen spitzen Winkel ( ) einschließen.2. Force measuring device (1) according to claim 1, characterized in that the two legs of the spring elements (21, 22, 23, 24) each form an acute angle ().
3. Kraftmessvorrichtung (1) nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Wandstärke (d) eines Federelementes ' (21, 22, 23, 24) ausgehend von dem oberen- starren Gehäuseteil (25) zunächst abnimmt und anschließend, zum Scheitelpunkt der Federschlaufe (21, 22, 23, 24) hin wieder zunimmt.3. Force measuring device (1) according to claim 1 or 2, characterized in that the wall thickness (d) of a spring element '(21, 22, 23, 24) starting from the upper rigid housing part (25) first decreases and then, to the apex the spring loop (21, 22, 23, 24) increases again.
4. Kraftmessvorrichtung nach einem der vorherigen Ansprüche, dadurch gekennzeichnet, dass das Gehäuse (2) mindestens vier U-förmige Federelemente (21, 22, 23, 24) aufweist, wobei jeweils zwei Federelemente (24, 21, 23, 22) in die selbe Richtung, von der Schnittfläche (AA) fortweisen. 4. Force measuring device according to one of the preceding claims, characterized in that the housing (2) has at least four U-shaped spring elements (21, 22, 23, 24), two spring elements (24, 21, 23, 22) each in the same direction, away from the cut surface (AA).
5. Kraftmessvorrichtung (1) nach Anspruch 4, dadurch gekennzeichnet, dass der untere starre Gehäuseteil (26) eine Befestigungslasche (4) zwischen zwei in die selbe Richtung von der Schnittfläche (AA) fortweisenden Federschlaufen (21, 24, 22, 23) aufweist, mit welchen die Kraftmessvorrichtung (1) mit Hilfe von geeigneten Befestigungsmitteln (7) , insbesondere Schrauben (7), starr mit dem Fahrzeug Chassis verbindbar ist, 5. force measuring device (1) according to claim 4, characterized in that the lower rigid housing part (26) has a fastening tab (4) between two in the same direction from the Has cut surface (AA) with spring loops (21, 24, 22, 23), with which the force measuring device (1) can be rigidly connected to the vehicle chassis with the aid of suitable fastening means (7), in particular screws (7),
EP05707831A 2004-03-03 2005-01-24 Force-sensing device Withdrawn EP1721135A1 (en)

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DE102004010367A DE102004010367A1 (en) 2004-03-03 2004-03-03 Force measuring device
PCT/EP2005/050286 WO2005085777A1 (en) 2004-03-03 2005-01-24 Force-sensing device

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KR20060132986A (en) 2006-12-22
US7402763B2 (en) 2008-07-22
DE102004010367A1 (en) 2005-09-29
US20070180930A1 (en) 2007-08-09

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