WO2009095326A1 - Force sensor - Google Patents

Force sensor Download PDF

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Publication number
WO2009095326A1
WO2009095326A1 PCT/EP2009/050530 EP2009050530W WO2009095326A1 WO 2009095326 A1 WO2009095326 A1 WO 2009095326A1 EP 2009050530 W EP2009050530 W EP 2009050530W WO 2009095326 A1 WO2009095326 A1 WO 2009095326A1
Authority
WO
WIPO (PCT)
Prior art keywords
force sensor
bending plate
force
characterized
preceding
Prior art date
Application number
PCT/EP2009/050530
Other languages
German (de)
French (fr)
Inventor
Norbert Koczwara
Original Assignee
Werner Turck Gmbh & Co. Kg
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
Priority to DE102008006475.0 priority Critical
Priority to DE102008006475 priority
Priority to DE200810037572 priority patent/DE102008037572A1/en
Priority to DE102008037572.1 priority
Application filed by Werner Turck Gmbh & Co. Kg filed Critical Werner Turck Gmbh & Co. Kg
Publication of WO2009095326A1 publication Critical patent/WO2009095326A1/en

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01LMEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00Measuring force or stress in general
    • G01L1/14Measuring force or stress in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
    • G01L1/142Measuring force or stress in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators using capacitors
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01LMEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00Measuring force or stress in general
    • G01L1/18Measuring force or stress in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01LMEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00Measuring force or stress in general
    • G01L1/20Measuring force or stress in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
    • G01L1/22Measuring force or stress in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
    • G01L1/2206Special supports with preselected places to mount the resistance strain gauges; Mounting of supports
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01LMEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00Measuring force or stress in general
    • G01L1/20Measuring force or stress in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
    • G01L1/22Measuring force or stress in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
    • G01L1/2206Special supports with preselected places to mount the resistance strain gauges; Mounting of supports
    • G01L1/2231Special supports with preselected places to mount the resistance strain gauges; Mounting of supports the supports being disc- or ring-shaped, adapted for measuring a force along a single direction

Abstract

The invention relates to a force sensor with a housing comprising force application sections at two housing sides facing away from one another.  A force sensor is proposed, comprising a circular disk-shaped elastically flexible bending plate (5), one edge of which is rigidly connected to a housing part (4) of the force sensor, a force application member (6) which engages perpendicular to the surface extent of the bending plate (5), and means (13, 15, 16) for measuring the deflection of the bending plate (5).

Description

force sensor

The invention relates to a force sensor with a housing which has at two spaced housing sides facing away force introduction sections up.

Force sensors are particularly needed in medical technology. In syringes, the piston is shifted from a slow running motor continuously into the cylinder to dispense doses the liquid located in the cylinder. In order to detect faults in time to be arranged, a force sensor between the piston and piston drive. Force sensors are used in addition also for pressure switch.

In the prior art pressure sensors are known. These pressure sensors besit- zen a monolithic ceramic body having a cup-shaped configuration. The bottom of the pot forms a flexure that flexes, depending on the applied pressure. A piezoelectric floor shows the US 4,594,898.

The invention has for its object to provide a simply constructed force sensor.

The object is achieved by the invention specified in the claims, each claim constitutes a separate solution of the problem.

First and foremost, a force sensor is provided with a flexurally elastic bending plate. This bending plate is fixedly connected to at least an edge portion with a housing part of the force sensor. The bending plate can bar-shaped or circular disc. It can be fully connected with its edge to the housing part. But it can also only with egg nem or two opposite edges of connectedness with the housing part be the. The following features are optional embodiments of the invention. To the center or any other portion of the flexure plate acts, optionally with the interposition of a plastic disc, a force introduction member. The force application member cooperates with a curved surface on the bending plate. Depending on the applied pressure, the bending plate bends. Means are provided to measure the deflection of the flexure. These means may be piezoresistive resistors, arranged in different places on the fuel introduction side facing away from the bending plate. It may be the same be applied by screen printing large or different-sized fields. This may be electrically interconnected in the form of a bridge circuit with each other. The resistors of such applied to the surface of the flexure fields vary depending bend. It is also provided to measure the deflection by means of strain gauges. Alternatively, the bending plate may also have a metal coating. This metal coating may form a second metal layer a capacitor. At a deflection of the bending plate, the distance between the two metal layers is changed, so that the capacitance of this capacitor changes. It is also possible to measure the deflection by reflection optical. The force application organ is in the simplest case a ball. A surface portion of the ball presses against the bending plate. The opposite portion of the ball protrudes through an opening of a housing cover and forming a force introduction zone. The bending plate can be part of a ceramic body. The ceramic body has a cup shape. The bending plate forms the bottom of the pot and is integral with the ZY-relieving portion of the ceramic body, respectively. It can especially be a monolithic ceramic body has an ABO 3-body. To avoid surface pressure maxima, is a plastic disc between force introduction surface of the ball and bending plate. The plastic disc is flexurally softer than the bending plate. In the housing, a circuit may be arranged for converting the values ​​supplied by the piezo- resistive transducers. The plastic disk is not necessary, if the force introduction member having a curved surface acted upon directly the center of the bending disk. The corresponding portion of the force introduction member may be formed soft. But it can also have a slightly curved surface corresponding to the curvature of the contour of the bending contour of the maximum deflected bending plate. Thus, the force application zone of the contour line of the bent by bending plate hugs and thus increased with increasing force initiated the contact surface and thus keeps the surface pressure at a low level. The force application member may be a stamp or a steel ball.

The bending plate may be a circular disc. It is then preferably connected to the surrounding housing part with its entire periphery. This connection may be the same material. In a further development of the invention it is provided that the bending plate is a bending beam. This is preferably fixedly connected only with two opposite ends with the housing. The bending beam preferably has a substantially rectangular outline contour ge in, so that two opposite rectangular sides, which are in particular the narrow sides, are connected to the housing part. Both these junctions interconnecting rectangle sides are not connected to the housing part, so that the bending beam can bend freely. Also in this embodiment of the bending beam can be formed by the bottom of a cup-shaped opening. The two free edges of the bending beam can be formed by a free cut. The cutout is preferably formed by two mutually parallel slots. In a further variant it is provided that the bending beam is connected flat with a circuit board which also carries other electronic circuit elements. The sensors for measuring the deflection of the bending beam, can be arranged on the board, the mitbiegt with the bending beam. Here, too, strain gauges are provided as measuring elements.

Embodiments of the invention are explained below with reference to accompanying drawings. Show it:

Fig. 1 in cross-section a first embodiment;

2 shows a section according to line II - II in FIG. 1;

Fig. 3 is a view according to a second embodiment of Fig. 1;

Fig. 4 is a representation according to a third embodiment of Fig. 1;

Figure 5 shows a fourth embodiment of the invention in a representation according to FIG. 3.

Fig. 6 is a bottom view according to arrow VI in Fig. 5 and

Fig. 7 is a plan view according to arrow VII in Fig. 5.

In the example shown in the Figure 1 embodiment sits inside of a plastic or other suitable material housing 1, a ceramic body 3. The ceramic body 3 is made of alumina and has a pot shape. The outer bottom of the ceramic body 3 is seated on an encircling step of the housing 1 in such a way that the thin-walled bowl bottom may sag. Within the cavity of the monolithic crystalline ceramic body 3 there is a plastic disc 8, which extends over the entire cylindrical bending plate 5 forming the bottom surface of the ceramic body. 3 The center of the plastic disc 8, which is flexurally softer than the bending plate 5 is acted upon by a curved surface. 7 In the example shown in the Figure 1 embodiment, the force application member 6 is a sphere. This rests in the cavity of the pot of the ceramic body 3, that is inside the cylinder section. 4 The plastic sheet 8 may also be smaller than the deflection plate 5. The plastic disc 8 then has a smaller diameter than the diameter of the diaphragm 5. In the edge region of the plastic disc 8 can also have one phase.

The housing 1 is provided with a cover 2, which has an opening in the center. 9 Through this opening protrudes a coupling surface of the steel ball 6. The projecting through the opening 9 portion forms a force introduction section 10th

The bottom of the housing 1, which faces the opening 9, also forms a force introduction section. 11

In a space between the bottom of the housing 1 and the bending plate 5, an electronic circuit is disposed on a circuit board 12th This is electrically conductively connected to a resistance device on the outer side of the bending plate. 5

As is apparent from Figure 2, a total of four resistance pads 13 are printed on the outer side of the bending plate. 5 The resistance surfaces 13 are made of a material which is applied in a pasty state. the material solidifies and has a piezo- sistive property in the solidified state. The thus manufactured resistors 13 change their resistance when the bending plate 5 bends. By a suitable circuit such as bridge circuit, the change in resistance, which, according to the flexing occurs can be measured. Temperature influences can be compensated.

The function of the embodiment shown in Figures 1 and 2 is as follows:

Applying a designated F force on the force application zone 10 of the ball 6, so an equal counter force F. arises causes This force that the curved surface 7 of the ball pushing 6 in the plastic disc 8 on the opposite force introduction zone. 11 The force is further introduced through the center in the bending plate. 5 The latter bends.

In the example shown in the Figure 3 embodiment of the force introduction member is designed differently. At the end of a shaft, a punch 14 is seated, which extends substantially over the entire cross section of the cavity of the ceramic body. 3 It has a flat curved bearing surface 7, with which the die 14 rests directly on the inside of the bending plate. 5 The curvature of the surface 7 is adapted to the curvature of cross-sectional contour of the bending plate 5, when it is maximally curved. This creates a minimized surface pressure in the application of force.

In the example shown in the Figure 3 embodiment, the bending plate 5 is also coated with a conductive layer 15 °. These are a metal layer.

One of the bending plate 5 spaced surface, in the embodiment, the bottom surface of the housing 1 is also coated with metal. This parallel to the coating 15 extending metal layer 16 forms a plate capacitor together with the layer 15 °. bending the plate 5 deflects so comparable to the capacitance of the plate capacitor changes. The change in capacitance can be measured in a known manner, for example by means of a resonant circuit.

In the example shown in the Figure 4 embodiment, an overload safety device is additionally provided. Here, the ceramic body 3 is not supported on a peripheral edge of the housing 1, but on spring elements 17 on the bottom of the housing. Is now applied a force on the ball apex 11 of the force introduction member 6, so not only the bending plate bends 5. Also, the spring elements 17 are rather compressed, which is accompanied by a removal of the ceramic body 3 from the opening. 9 The ball 10 therefore emerges not only according to the bending of the bending plate 5 deeper into the opening 9, but also, according to the alternate movement of the entire ceramic body 3 against the spring elements 17. This is performed until the vertex of the ball 6 flush rests in the opening 9 , then be higher forces applied to the sensor, they will be introduced directly into the housing 1, so that the maximum stress of the bending plate 5 is limited.

In the example shown in Figures 5 and 7 embodiment, the bending plate 5 is different from non-circular shaped in the previously described embodiments, and connected with all its circular edge with the cylindrical body. 4 In the example illustrated in the figures 5 to 7 embodiment, the bending plate 5 is rather formed by a bending beam. In this embodiment, the housing part 4, which forms the cavity in which the punch 14 is disposed, rectangular gestal- tet. The bottom of this cavity is also formed here from the bending plate. 5 The bending plate 5 has a substantially rectangular cross section. The two opposite narrow sides of the bending plate 5 1 5 are fixedly connected to the housing part. 4 The transverse thereto rectangular sides 5 'of the bending plate 5, however, are not connected to the housing part. 4 These free edges 5 "of the bending plate 5 are formed by free cuts 18th Also in this embodiment, the material of the housing 4 and integrally connected to the housing 4 bending plate 5 is made of a ceramic hybrid. The cut-outs 18, which extend substantially over the entire longitudinal extension of the bottom of the cavity of the housing 4 are preferably made after fabricating the housing 4 formed by the sealing layer hybrids. This can be done by cutting, for example. With a laser beam.

As is further apparent from Figure 5, the ceramic housing 4 is embedded in a plastic housing 1, which also forms the cover. 2 The lid 2 has an opening 9 through which protrudes the force introduction member 10 which is fixedly connected to the plunger 14 as well.

The figure 7 it can be seen that the force introduction member 10 is wider than the bending plate. 5

The bending plate 5 and the cavity forming the housing 4 forming ceramic body is so bonded to a circuit board 19 that the deflection of the bending beam 5 leads to a partial deflection of the board 19th To this end, the outwardly facing surface of the bending beam 5 is connected flat with the top of the board 19th The circuit board 19 also has cutouts which are located at the site of cut-outs 18 and are slightly larger.

On the side facing away from the bending beam 5, the plate 19 carries a strain gauge bridge. This is arranged between the two slots and able to convert the deflection of the circuit board 19 in electrical properties. a circuit 20 which is also arranged on the circuit board is used to evaluate these electrical values. Also in the example shown in the figures 5 to 7 embodiment is a force sensor used in the monitoring of an automatic infusion device. There syringes are motor-driven to inject a drug over a long period at a constant flow rate for example. Two different disturbances, among others: the pressure in the hose towards the infusion needle is decreasing, for example because the supply is exhausted, or the pressure increases, for example because there is clogging or the hose is kinked. Both faults can be monitored by one of the previously registered loading arrangements. Monitoring is performed by the tube is led to the injection needle through a monitoring unit.

All disclosed features are essential to the invention (to himself). In the disclosure of the application barung The disclosure content of the associated / accompanying priority documents is hereby included (copy of the prior application) in full, also for the purpose of incorporating features of these documents in claims of the present application.

Claims

1. force sensor with a bending elastic circular disc-shaped bending plate
(5), which is connected to at least one edge portion secured to a housing part (4) of the force sensor, engaging with a perpendicular to the surface extension of the bending plate (5) force introduction member (6) and means (13, 15, 16) for measuring the deflection the bending plate (5).
2. A force sensor according to claim 1 or in particular according thereto, characterized in that the bending plate (5) is a uniform material with a housing part (4).
3. A force sensor according to one or more of the preceding claims or in particular according thereto, characterized in that the housing part (4) together with the bending plate (5) comprises a ceramic body (3) in particular of AI2O3 formed.
4. A force sensor according to one or more of the preceding claims or in particular according thereto, characterized in that the force introduction member (6) with a rounded portion (7) on the bending plate (5) engages.
5. A force sensor according to one or more of the preceding claims or in particular according thereto, characterized in that the force introduction member (6) engages in a housing of the part (4) formed cavity.
6. A force sensor according to one or more of the preceding claims or in particular according thereto, characterized in that the rounded portion (7) is formed of a spherical surface.
7. Force sensor according to one or more of the preceding claims or in particular according thereto, characterized in that the contour of the curved surface (7) of the contour line a deflected maximum
Bending plate (5) is approximated.
8. A force sensor according to one or more of the preceding claims or in particular according thereto, characterized in that the edge of Biegplatte (5) entirely with the housing part (4) and in particular runs on a circular line.
9. force sensor according to one or more of the preceding claims or in particular according thereto, characterized in that the bending plate (5) only on two opposite edges on the housing part
(4) is fixed.
10. Force sensor according to one or more of the preceding claims or in particular according thereto, characterized in that the bending plate (5) is located between two open cuts (18) extending bending beam.
11. Force sensor according to one or more of the preceding claims or in particular according thereto, characterized by an introduction organ between the force (6) and the bending plate (5) arranged disc (8) which is flexurally softer than the bending plate (5).
12. Force sensor according to one or more of the preceding claims or in particular according thereto, characterized in that the disc (8) used a in the cavity of the housing (4), the bottom zumin- least partially covering plastic washer (8).
13. Force sensor according to one or more of the preceding claims or in particular according thereto, characterized in that the means for measuring the deflection of the bending plate (5) are piezoresistors.
14. Force sensor according to one or more of the preceding claims or in particular according thereto, characterized in that the means for measuring the deflection of the bending plate (5) strain gage (13).
15. Force sensor according to one or more of the preceding claims or in particular according thereto, characterized in that the bending plate (5) is a metal coating (15) comprises part of a Plattenkondensa- tors (15, 16).
16. Force sensor according to one or more of the preceding claims or in particular according thereto, characterized by a by a spring element (17) formed overload protection device, wherein the spring element (17) is arranged in the force path of the force sensor and the maximum displacement travel of the force introduction member (6) is limited.
17. Force sensor according to one or more of the preceding claims or in particular according thereto, characterized in that a force trans- portion (10) of the force introduction member (6) through an opening (9) of the housing (2) extending through and flush when it reaches the limit force in the plane of the housing opening (9).
18. Force sensor according to one or more of the preceding claims or in particular according thereto, characterized in (6) is that the transmission of force organ (6) in a pot opening of the housing (4) inset steel ball with a force introduction section (10) by a housing opening (9) protrudes.
arranged 19th force sensor according to one or more of the preceding claims or in particular according thereto, characterized by an on the force introduction member (6) opposite the bending plate (5), with the bending plate (5) surface associated board (19), which (the center comprising 13) for measuring the deflection and WEL addition che an electronic circuit elements (20).
PCT/EP2009/050530 2008-01-29 2009-01-19 Force sensor WO2009095326A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
DE102008006475.0 2008-01-29
DE102008006475 2008-01-29
DE200810037572 DE102008037572A1 (en) 2008-01-29 2008-11-21 force sensor
DE102008037572.1 2008-11-21

Publications (1)

Publication Number Publication Date
WO2009095326A1 true WO2009095326A1 (en) 2009-08-06

Family

ID=40822273

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2009/050530 WO2009095326A1 (en) 2008-01-29 2009-01-19 Force sensor

Country Status (2)

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DE (1) DE102008037572A1 (en)
WO (1) WO2009095326A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2713148A1 (en) * 2012-09-27 2014-04-02 Honeywell International Inc. Mechanically coupled force sensor on flexible platform assembly structure
DE102017121347A1 (en) 2017-09-14 2019-03-14 Turck Holding Gmbh Hose pressure sensor for a peristaltic pump arrangement

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9869598B1 (en) * 2016-06-24 2018-01-16 Honeywell International Inc. Low cost small force sensor

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4454771A (en) * 1980-11-07 1984-06-19 Hitachi, Ltd. Load cell
DE4103856A1 (en) * 1991-02-08 1992-08-13 Pfister Messtechnik Force or pressure measurement arrangement of easily varied design - has modular construction of plates, at least one having annular ring and gap contg. elastomeric force transfer material
US5760313A (en) * 1997-03-05 1998-06-02 Honeywell Inc. Force sensor with multiple piece actuation system
US6491647B1 (en) * 1998-09-23 2002-12-10 Active Signal Technologies, Inc. Physiological sensing device
US20040083825A1 (en) * 2002-11-05 2004-05-06 Tanita Corporation Diaphragm type load detection sensor, load detection unit and electronic scale using same
US20040181312A1 (en) * 2003-03-13 2004-09-16 Akito Miura Robot apparatus and load sensor
US7082844B1 (en) * 2005-02-16 2006-08-01 Cts Corporation Strain sensor having improved accuracy
US20070251328A1 (en) * 2006-04-26 2007-11-01 Honeywell International Inc. Force sensor package and method of forming same

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2141231B (en) 1983-06-07 1986-08-06 Gen Electric Co Plc Force sensors

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4454771A (en) * 1980-11-07 1984-06-19 Hitachi, Ltd. Load cell
DE4103856A1 (en) * 1991-02-08 1992-08-13 Pfister Messtechnik Force or pressure measurement arrangement of easily varied design - has modular construction of plates, at least one having annular ring and gap contg. elastomeric force transfer material
US5760313A (en) * 1997-03-05 1998-06-02 Honeywell Inc. Force sensor with multiple piece actuation system
US6491647B1 (en) * 1998-09-23 2002-12-10 Active Signal Technologies, Inc. Physiological sensing device
US20040083825A1 (en) * 2002-11-05 2004-05-06 Tanita Corporation Diaphragm type load detection sensor, load detection unit and electronic scale using same
US20040181312A1 (en) * 2003-03-13 2004-09-16 Akito Miura Robot apparatus and load sensor
US7082844B1 (en) * 2005-02-16 2006-08-01 Cts Corporation Strain sensor having improved accuracy
US20070251328A1 (en) * 2006-04-26 2007-11-01 Honeywell International Inc. Force sensor package and method of forming same

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2713148A1 (en) * 2012-09-27 2014-04-02 Honeywell International Inc. Mechanically coupled force sensor on flexible platform assembly structure
DE102017121347A1 (en) 2017-09-14 2019-03-14 Turck Holding Gmbh Hose pressure sensor for a peristaltic pump arrangement

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