WO2008034890A2

WO2008034890A2 - Device for detecting a force and/or a torque

Info

Publication number: WO2008034890A2
Application number: PCT/EP2007/060011
Authority: WO
Inventors: Frank Grunwald
Original assignee: Continental Automotive Gmbh
Priority date: 2006-09-22
Filing date: 2007-09-21
Publication date: 2008-03-27
Also published as: WO2008034890A3; DE102006044779A1; DE102006044779B4

Abstract

The invention relates to a device for detecting a force and/or a torque, said device comprising an elastic element that can be deformed by the action of a force and/or a torque and surrounds an inner region, and a sensor for detecting a deformation of the element, caused by the force or the torque, forming electrical signals. The sensor is arranged in the inner region of the elastic element. The elastic element comprises at least one electroconductive structure which at least partially shields the sensor from electrical fields emanating from the region around the elastic element.

Description

description

Device for detecting a force and / or a torque

The present invention relates to a device for detecting a force and / or a torque, in particular for use in motor vehicles.

Devices of the type mentioned serve forces and

To detect torques between two coupling points of the device and in particular to form electrical signals that reflect the force or torque between the coupling points. For this purpose, corresponding devices according to the prior art have electrical or electronic devices for the conversion of forces, torques, displacements or movements in the signals.

In many applications of such devices, especially for example in motor vehicles, however, these are exposed to more or less strong, static or dynamic, electrical and / or magnetic fields from their environment that affect the signal formation and / or the signals of the respective device; in extreme cases, the signals may no longer be suitable for further meaningful processing.

The said devices are therefore often shielded by additional electrical films or sheets. However, these additional foils or sheets require an increased effort in the manufacture of the devices and increase the complexity of the device.

The present invention is therefore based on the object, a device for detecting a force and / or a

To create torque that is easy to manufacture and counter- is insensitive to the influence of external electrical and preferably also magnetic fields.

The object is achieved by a device for detecting a force and / or a torque with an elastic element, which is deformable by the force or the torque, and which surrounds an inner region, and a sensor for detecting a by the force or the Torque generated deformation of the element to form electrical signals, wherein the sensor is disposed in the inner region of the elastic element and the elastic element has at least one electrically conductive structure, the sensor against electric fields from the area around the elastic element at least partially shielded.

The basic structure of the device according to the invention therefore initially comprises the elastic element, which is deformed by the engaging force or the applied torque. The force or the torque acts between two Ankoppel- points that may lie directly in the elastic element or at least with respect to the direction of the force or the torque action firmly connected to the elastic element coupling elements.

For detecting the deformation of the sensor is used, which may preferably be a sensor with at least one electrical or electronic component; the sensor may preferably also have at least one signal processing circuit and / or at least one first stage of evaluation electronics for processing signals of the component. The sensor does not need to be directly connected to the elastic element, it is also possible to transmit the deformation by means of corresponding, connected to the elastic element coupling elements to the sensor. An essential idea of the invention is now to use the elastic element simultaneously for two functions, namely once for the implementation of the force or the torque in a detectable by the sensor deformation and the other to shield the sensor against at least electric fields.

For this purpose, the elastic element or, more precisely, the electrically conductive structure therein is preferably shaped in such a way that it forms an electric field, at least partially shielding, with respect to the electrical shielding. The structure or element may therefore in particular have holes, apertures, slots or similar intermediate spaces which do not significantly impair the shielding for a given purpose. The structure is formed depending on the type and size of the expected fields to be shielded and a predetermined maximum residual field strength at the location of the sensor.

Preferably, the structure is designed such that an impairment of signals generated by the sensor can be effected by predetermined for a given application electric fields only within a predetermined tolerance range.

Thus, a particularly simple construction of the device is achieved, which simultaneously leads to a greatly reduced sensitivity to electric fields acting in the environment of the device.

Since an additional shield can be omitted, the device requires a smaller overall space than known devices.

In principle, the device only has to have a shielding against electric fields, since this also affects the action of time-varying electromagnetic fields is reduced. However, the elastic element preferably comprises at least one soft-magnetic structure which at least partially shields the sensor against magnetic fields from the area around the elastic element. This structure can in principle be provided separately from the electrically conductive structure.

Preferably, however, contains the at least one electrically conductive structure soft magnetic material, so that the sensor is at least partially shielded from magnetic fields from the area around the elastic element. This embodiment has the advantage that a single structure is sufficient to at least partially shield dynamic, and in particular also static, both electrical and magnetic fields.

In both cases, the design of the structures is carried out according to the design of the electrically conductive structure.

In principle, the electrically conductive structure can be configured as desired. For example, it is conceivable that the elastic element consists of plastic, are introduced into the electrically conductive regions, for example of an electrically conductive plastic or graphite. Preferably, however, at least the electrically conductive

Structure of metal, more preferably of a soft magnetic metal. Such a device can have a particularly long life with a suitable choice of the metal and provide a very good shielding.

The elastic element may in principle be shaped in any way, as long as it fulfills the above two functions. It proves to be very advantageous if the elastic element comprises, as an electrically conductive structure, a spring which is formed from an electrically conductive spring material wound around the inner region. By selecting the type of spring and the spring constant of the spring, the be adapted in a very simple manner to a desired detection range for the forces or torques.

In particular, the elastic element may comprise a screw or coil spring made of metal as an electrically conductive structure. This embodiment has the advantage that on the one hand in many cases, a suitable spring is already available and does not need to be specially manufactured, and on the other hand, a very good shielding, in particular by selecting the pitch, can be achieved.

A particularly good shielding is achieved if the electrically conductive structure has meshes. The structure can then act electrically like a Faraday cage.

Particularly preferably, the elastic element comprises, as an electrically conductive structure, an elastically resilient basket with meshes of metallic material. Such a construction of the structure allows, in particular, that the basket also assumes the function of the elastic element, the elastic element consisting essentially of the basket. Such a basket has the further advantage that it can be stamped from a sheet and thus easily manufactured.

The sensor can in principle be of any desired design, provided it is suitable for detecting the deformation. For example, it can directly detect a deformation of the elastic element, as is conceivable, for example, in the case of a capacitive sensor. Preferably, however, the sensor comprises two relatively movable parts which are connected to portions of the elastic member which are moved relative to each other in a force or torque to be detected by deformation of the elastic member. This advantageously allows the use of different types of sensors and at the same time a very free design of the elastic element. At least one of the sections it may in particular be one of the coupling points.

The parts can be connected directly to the sections of the elastic element. Preferably, however, at least one of the parts of the sensor is held on a first holder which is connected to an engagement point on the elastic element. The connection can be formed directly or indirectly. This has the advantage that the parts of the sensor need not meet any special requirements for the attachment. In particular, the other part of the sensor can also be held at a second holder connected to a different point of engagement which is moved when the elastic element is deformed relative to the first point of application, the two holders being movable relative to one another and being deformed by deformation of the elastic element to be detected force or a torque to be detected are movable.

Particularly preferably, the coupling points between which the force or the torque acts formed on the holders. This has the advantage that the coupling can be made much more free.

Between the acting force or the acting torque and the deformation of the elastic element or relative movement of the holder to each other is preferably a fixed quantitative relationship. Therefore, the holders are particularly preferably subject to forced movement in their relative movement, so that the holders perform a predetermined movement relative to one another when the elastic element is deformed by a force to be detected or a torque to be detected. This ensures that only forces and torques are detected in a desired direction.

The forced operation can be realized, for example, by guiding the holders on a guide device are such that the holders perform a predetermined movement relative to each other in a deformation of the elastic member by a force to be detected or a torque to be detected. This enables a precise detection of the relative movement or relative position of the parts relative to one another.

Alternatively, the holders can be guided into or into each other and, in particular, designed so that the holders perform a predetermined movement relative to one another during a deformation of the elastic element by a force to be detected or a torque to be detected. This also allows an accurate detection of the relative movement or relative position of the parts to each other. This embodiment has the further advantage that an additional guide device is not absolutely necessary.

As sensors, any sensors may be considered, in particular those which operate without contact, i. whose two parts do not need to be touched during acquisition. In the apparatus, the sensor may comprise, in particular as a first part a magnet and as a second part a magnetic field sensor for detecting the field of the magnet, a change in the field of the magnet or the magnetic flux excited by the magnet or the flux change produced. As a magnetic field sensor is in particular a Hall sensor into consideration.

In particular, for detecting a torque, it proves to be advantageous if the sensor as a first part of a magnet and as a second part sensitive to directions of the magnetic field of the magnet sensor element, preferably a magnetoresistive sensor element comprises. Such sensor elements offer the advantage that direction-changing movements of the magnet, such as can occur during the detection of the torque, can be particularly sensitive and therefore accurate. In order to enable the best possible shielding even with large fields, in the device, the elastic element has a connection region, via which the electrically conductive structure is connectable to a ground potential.

The invention therefore also relates to a vehicle electrical system having a device according to the invention for detecting a force or a torque and a ground line which is connected to the connection region of the device.

The invention will be further explained by way of example with reference to the drawings. Show it:

1 is a schematic representation of a device for detecting a force,

Fig. 2 is a schematic representation of another device for detecting a force, and

Fig. 3 is a schematic representation of a device for detecting a torque.

In Fig. 1, a force detecting device 1 comprises an elastic member 2 surrounding an inner portion 3 and a two-piece sensor 6 supported on holders 4 and 5 for detecting deformation of the elastic member 2 generated by the force to form of electrical signals. The sensor 6 is arranged in the inner region 3 of the elastic element 2.

The elastic element 2 is in this embodiment, a coil spring made of a soft magnetic, electrically conductive spring steel. The pitch of the coil spring is chosen so that this, unlike in the schematic drawing tion, has the largest possible number of turns. The spring constant is chosen as a function of the maximum size of the forces to be detected so that a predetermined elastic change in length of the coil spring does not exceed a predetermined maximum value with effect of the maximum force.

In the space 3 enclosed by the elastic element, there are the two holders 4 and 5, which on the one hand have coupling points 7 and 8, to which external elements for power transmission can be coupled. On the other hand, each of the holders 4 and 5 is connected to another end of the elastic see element 2 as a point, so that a

Relative movement of the holder 4 and 5 along the screw axis of the elastic element to a deformation, here more accurate compression or expansion of the elastic element 2, in, in this example, preferably linear, dependence on the force leads. The holders therefore also serve as coupling elements.

The cylindrical in their basic form holder 4 and 5 are along the screw axis linearly guided by a guide, not shown, for example, a coaxial with the screw axis passing through a corresponding guide bore in the holders 4 and 5 extending rod.

The holders 4 and 5 are identical except for receptacles for parts of the sensor 6 and have at the mutually facing ends recesses 9 and 9 ', so that the ends each form only halves of a cylinder and are complementary to each other, so that the holders 4 and 5 are movable relative to each other. In this case, the end of each holder is arranged in the recess of the other holder and the flat opposite surfaces of the holder extend at least approximately parallel to each other.

The sensor 6 is designed as a two-part, non-contact sensor, and comprises a Hall sensor 10 as a magnetic field sensor and a permanent magnet as the second part

11. The Hall sensor 10 and the magnet 11 are in shots 12 and 13 in the holder 4 and 5 in the parallel to each other extending surfaces of the ends of the holder 4 and 5 in the region of the recesses 9 and 9 'arranged that the dipole of the magnet 11 parallel to the direction of the relative movement of the holder 4 and 5 and the screw axis of the elastic EIe- element 2 extends and a movement of the magnet 11 relative to the Hall sensor 10 can be detected by this.

In this exemplary embodiment, the Hall sensor 10 already has an evaluation device which processes and amplifies signals of a Hall element of the Hall sensor 10. Signals of the sensor 6 can be detected via a guided in the holder 4 signal line.

When a force is exerted between the holders 4 and 5, they are deformed, with deformation of the elastic element 2, which

Coil spring, moved relative to each other. The amount of movement is determined by the elastic properties of the elastic element 2. The movement corresponding to the force is detected by the sensor 6, which then emits corresponding detection signals.

The elastic element 2, which has an electrically conductive and soft magnetic structure or more precisely, in this example the helical spring, forms a kind of cage which shields both electrical and magnetic static or dynamic fields with respect to the interior 3 and thus to the sensor 5. The sensor is preferably arranged in the direction of the axis of the coil spring in the middle third. This results in a particularly compact design with good shielding.

A particularly good shielding results when the electrically conductive structure, that is, here the coil spring 2 is connected via a connection region or ground connection 14 to a ground line, for example, to a motor vehicle electrical system of a motor vehicle. A second exemplary embodiment in FIG. 2 differs from the first exemplary embodiment only in that the elastic element 2 in the form of a helical spring is now replaced by an elastic element 16 made of a cylindrical basket punched from a soft magnetic metal sheet, and an arrangement of stitches 17 comprises. These meshes allow a particularly good shielding of electrical and magnetic fields.

Preferably, the stitches are formed so that in

Direction of the force to be detected each meandering structures without kinks result. Thus, a particularly good elastic behavior can be achieved.

All other parts are unchanged from the first embodiment.

A third embodiment in Fig. 3 differs from the first embodiment in that now the device for detecting a torque is formed.

For this purpose, similar to the first exemplary embodiment, in their basic form cylindrical holders 4 'and 5' are arranged in the inner region 3 of the elastic element 2 and fixedly connected to the ends or coupling points of the elastic element 2. Unlike the first embodiment, however, the holders 4 'and 5' are rotatably supported relative to one another about their coaxial cylinder axes by means of a journal 15, so that they are only rotatably rotatable relative to one another.

Instead of the Hall sensor 10, a sensitive to the direction of the magnetic field of the magnet 11 sensor element 18 is now used, in the example, a suitably oriented magnetoresistive element, now in a receptacle 12 'in the holder 5' facing end face in the vicinity the circumference of the holder 4 'is held. The magnet 11 is located in a receptacle 13 'in a corresponding position in the holder 5'. The magnet 11 is held so that the dipole now runs parallel to a tangent to the circumference of the holder 9 '. The magnetoresistive sensor element 18 is oriented in its receptacle in such a way that it can detect the change in the direction of the magnetic field caused by rotation of the holders 4 'and 5' relative to one another and output a corresponding detection signal.

When torque is transmitted to one of the holders while the other is fixedly mounted, this torque results in rotation of the holders relative to each other, which in turn deforms the elastic element 2 in response to the torque. The size of the rotation, which is dependent on the magnitude of the torque, is detected by means of the sensor 6, which then outputs a corresponding detection signal.

Claims

claims

1. A device for detecting a force and / or a torque with - an elastic element (2; 16) which is deformable by the force or the torque, and which surrounds an inner region (3), and - a sensor (6) for detecting a deformation of the element (2; 16) generated by the force or the torque with the formation of electrical signals, wherein the sensor (6) in the inner region (3) of the elastic element (2; 16) is arranged and the elastic Element (2; 16) has at least one electrically conductive structure (2; 16) which at least partially shields the sensor (6) against electric fields from the area around the elastic element (2; 16).

2. Device according to claim 1, wherein the elastic element (2; 16) comprises at least one soft-magnetic structure (2; 16) which seals the sensor (6) against magnetic

Fields from the area around the elastic element (2; 16) at least partially shields.

3. Device according to claim 1 or claim 2, wherein the at least one electrically conductive structure (2; 16) contains soft magnetic material, so that the sensor (6) against magnetic fields from the area around the elastic element (2; 16) at least partially shielded.

4. Device according to one of the preceding claims, wherein the electrically conductive structure (2; 16) is made of metal.

5. Device according to one of the preceding claims, wherein the elastic element (2) as an electrically conductive structure comprises a spring (2), which consists of a to the Inner region (3) wound electrically conductive spring material is formed.

6. Device according to one of the preceding claims, wherein the elastic element (2) as electrically conductive

Structure comprises a screw or coil spring (2) made of metal.

7. Device according to one of the preceding claims, wherein the electrically conductive structure (16) mesh (17).

8. Device according to one of the preceding claims, in which the elastic element (16) as an electrically conductive structure (16) comprises an elastically resilient basket with meshes (17) of metallic material.

9. Device according to one of the preceding claims, wherein the sensor (6) comprises two relatively movable parts (10, 11, 18, 11) which are connected to portions of the elastic element (2; detecting force or torque action by deformation of the elastic member (2; 16) are moved relative to each other.

A device according to claim 9, wherein at least one of the parts (10; 18) of the sensor (6) is held on a first holder (4; 5) which is connected to an engagement point on the elastic element (2; 16) ,

11. The device according to claim 10, wherein the other part (11) of the sensor (6) on a second holder (4 ', 5') is held, wherein the two holders (4, 4 ', 5,5') movable relative to each other and by deformation of the elastic element (2; 16) by a to be detected

Force or a torque to be detected are movable.

12. The device according to claim 10, wherein the holders (4, 4 ', 5, 5') are subject to a positive guide (15), such that the holders (4, 4 ', 5, 5') undergo deformation of the elastic element (2; 16) perform a predetermined movement relative to each other by a force to be detected or a torque to be detected.

13. The apparatus of claim 11 or 1, wherein the holder on or are guided into each other.

14. Device according to one of the preceding claims, wherein the sensor as the first part of a magnet (11) and as a second part of a magnetic field sensor (10) for detecting the field of the magnet, a change of the field of the magnet or of the magnet excited by the magnet Flow or flow change generated.

15. Device according to one of the preceding claims, in particular for detecting a torque, wherein the sensor as a first part comprises a magnet (11) and as a second part sensitive to directions of the magnetic sensor element (18), preferably a magnetoresistive sensor element ,

16. Device according to one of the preceding claims, wherein the elastic element (2; 16) has a connection region (14) via which the electrically conductive structure (2; 16) can be connected to a ground potential.