WO2011113166A2

WO2011113166A2 - Sensor having a deformation-decoupled clamping device

Info

Publication number: WO2011113166A2
Application number: PCT/CH2011/000048
Authority: WO
Inventors: Josef Glaser
Original assignee: Kistler Holding Ag
Priority date: 2010-03-18
Filing date: 2011-03-10
Publication date: 2011-09-22
Also published as: WO2011113166A3; CH702915A1

Abstract

The invention relates to sensor that has an axial orientation, comprising a housing (2), which has a measuring element (3) in a recess (11) and a clamping device (4) arranged radially outside of the housing (2) and having two opposite surfaces (5, 6) extending perpendicularly to the axial direction, and a clamping sleeve (8) for installing the clamping device (4) on a component (9). The clamping device (4) is supported at the first surface (5) thereof on a protrusion (10) of the component (9) in the installed state and is clamped at the second surface (6) thereof by the clamping sleeve (8), which is threaded with the component (9). According to the invention, the clamping device (4) has a tubular shape between the two surfaces (5, 6) and is arranged radially spaced apart from the component (9). In addition, the clamping device is connected to the housing (2) by a narrow web (7) only in the middle area of the clamping device so that the clamping device (4) transmits neither an axial nor a radial stress of the component (9) onto the housing (2) during use. Thus, a faulty measurement of the measuring element (3) is prevented.

Description

SENSOR WITH DEFORMING DECOUPLED SINGLE VOLTAGE DEVICE

Technical area

The invention relates to a sensor with an axial alignment comprising a housing with a measuring element in a recess and a radially outside the housing arranged clamping device with two opposite, transverse to the axial direction surfaces and a clamping sleeve for mounting the clamping device to a component, wherein the Clamping device is supported in the mounted state on its first surface on a shoulder of the component and on its second. Surface of the clamping sleeve, which is bolted to the component, is clamped.

State of the art

The sensors described here are used, for example, on structures which are subjected to strong deformations during the measurement. Examples are pressure sensors in cylinder heads of internal combustion engines. Deformations that act a- xial and / or radial of the structure on a housing of such a sensor, also deform the frontally arranged membrane of such a sensor and thereby distort the measurement.

Known solutions relate, for example, to decoupling of sensor housing and structure in the region of the sensor. As a result, only radial, but not axial deformations are decoupled. Other known. Solutions concern a reset of the sensor from the heat chamber. However, the thus created ^¬ pipe-shaped bore allows a pipe vibration, which • also have a disturbing effect on the measurement. From EP0395622 a shoulder-sealing pressure sensor is specified in a component. This takes on the sealing shoulder (level 6) on both axial and radial deformations acting on the membrane via the measuring element. Another disadvantage of such an arrangement is that in hot processes, the large surface of the front side of the housing is exposed to the heating. This can lead to overheating of the diaphragm as well as to the destruction of the sensor. In addition, the sensor is firmly clamped by the assembly between the sealing shoulder and a rear, chamfered clamping. Tensions, which act on the front Einspannschul ^¬ ter and / or on the adjoining the rear shoulder to ^¬ ordered thread from the component to the clamping area, are connected by this directly to the sensor housing, since this is rigidly connected to the clamping area.

In EP 1531323 an attachment for a pressure sensor is proposed, which is clamped directly radially outside the sensor ^¬ device towards the component by means of a seal, whereby a radial force is built up on the sensor element from the housing ago. This ensures that pressure ^¬ sensors are built with small overall diameters Kings ^¬ nen. Unfortunately, these are very sensitive to heat and, in particular because of the sealing elements made of rubber, ungeeig ^¬ net for measurements in hot environments such as combustion chambers. DE 4234290 also describes a pressure sensor with a seal acting on the front side, radially on the measuring device, which is used primarily in the foodstuffs sector, but is also unsuitable for use in hot areas.

Presentation of the invention

Object of the present invention is to provide a sensor with a clamping device mentioned above, which is used in hot areas, insensitive to axial and radial deformations of the component and is not disturbed by pipe vibrations.

The object is achieved according to the invention by the clamping device between the two surfaces of tubular design and is arranged radially spaced from the component through an annular gap. Your only connection to the housing forms a narrow web, which is mounted in the central region of the jig. The Einspannvorrich ^¬ tung thus transmits either an axial or a radial stress from the component to the housing and verhin ^¬ changed by an incorrect measurement of the measuring element in use.

In longitudinal section, the tubular clamping device with its centrally located web to the sensor housing on each side resembles a "T", which apart from the three free ends of the two lines are arranged without contact to other components the pipe ends, are the clamping components clamping sleeve and component, above the annular gap to the component out. At the bottom . Finally, the sensor housing is finally attached to the "T", the bridge. kung in the radial direction, since it is very thin relative to its axial length, so that hardly transfer forces from the pipe ends on the web.

Further embodiments according to the invention are specified in the subclaims.

Brief description of the drawings

The invention will be explained in more detail below with reference to the drawings. Show it

1 shows a sensor with a housing and a measuring element in a recess provided for this purpose;

Fig. 2 is a sensor of Figure 1 in the installed state of the prior art.

Fig. 3 is a front-sealing sensor in the installed state of the prior art;

4 is a screwed front sealing Sens ^' or in ^¬ built state according to the prior art;

5 shows an improved sealing shoulder sensor in a ^¬ assembled state according to the prior art.

Fig. 6 is an improved front-sealing sensor in the installed state of the prior art;

7 shows a front-sealing sensor according to the invention in the installed state; 8 shows a shoulder-sealing sensor according to the invention in the installed state;

9 shows a shoulder-sealing sensor according to the invention in the installed state with heat shield; Fig. 10a-f variants of the clamping devices.

Ways to carry out the invention

Fig. 1 shows a conventional sensor 1 with a housing 2 with a measuring element 3 in a Ausspa ^¬ tion provided therein 11. The housing 2 is constructed axially and front side with a membrane 14, behind which in this embodiment, a plunger 15 is mounted. This can transmit a frontal pressure acting on the diaphragm 14 pressure on the Messele- ment 3.

Usually, piezoelectric, piezoresistive or optical measuring elements 3 are used. The structure of FIG. 1 is only one possible, typical structure of a sensor 1. An ^¬ constructions are also common and also form the basis of the structures shown further.

FIGS. 2 to 6 form sensors 1 with clamping devices according to the prior art. In FIG. 2, a sensor 1 is shown in FIG. 1, which is turned ^¬ simply screwed in a component 9. Accessed from the mounting thread 16 both axial and radial deformations of the housing 2 for Messele ^¬ element 3. Fig. 3 shows an end-sealing sensor 1, which is not screwed directly as the sensor 1 in Fig. 2, but at a front paragraph 10 supported on the component 9. Is held the housing 2 at the back by means of a clamping sleeve 8, which is attached to a mounting thread 16 on the component 9.

In this arrangement, radial deformations pass from the component 9 via the shoulder 10 over very short distances to the measuring element, for example in the case of strong heating of the component 9. In addition, axial deformations when screwing in a clamping sleeve 8 provided for mounting compress the housing 2, which also occurs affects the measuring element 3 via the membrane 14.

FIG. 4 shows a further end-sealing sensor 1. In contrast to. Arrangement in Fig. 2 or 3, the housing 2 is configured on the front side in a tube, which is arranged radially ^¬ spaced from the component 9. As a result, radial deformations hardly reach the measuring element 3 via the shoulder 10. For this, axial deformations between the shoulder 10 and the mounting thread 16 compress the housing 1 in the area around the measuring element 3. The axial and radial deformations on the mounting thread 16 also have a short path on the measuring element 3.

A similar arrangement as in FIG. 3 is shown in FIG. 5, but as a shoulder-sealing sensor. In these sensors 1, the front region of the housing 2 is arranged without contact with the component 9. Since the housing part 2 is completely free in the area of the measuring element 3, the measuring element 3 is not affected by disturbing deformations. The disadvantage of such an arrangement is that in hot processes, the large, exposed to the heating surface of the face of the housing 2 and the membrane 14 to the overheating ^¬ wetting and may eventually lead to the destruction of the sensor. 1 6, this problem has been solved in that the sensor 1 has again been carried out in a front-end sealing manner, wherein the measuring element 3 is arranged in the housing 2 set far back. Again, the entire housing element 2 comprising the measuring element 3 is completely free and thus not affected by deformations. Mandatory here is the exempted large axial distance between the rear end of the mounting thread 16 and the membrane 14. In the long, prevailing in front of the membrane 14 channel 17 arise pipe vibrations, which in turn have a disturbing effect on the measurement. In addition, heat, which flows into the sensor 1, can be dissipated poorly.

It turns out that a new problem always occurs when trying to fix a problem.

The now described arrangements of sensors 1 according to the invention of FIGS. 7, 8 and 9 are now intended to eliminate all the problems listed above and not generate any new ones.

FIG. 7 shows a front-end sealing sensor 1 according to the invention. In turn, it comprises a housing 2 with a measuring element 3 in a recess 11 provided therein. The housing 2 has an axial construction and is closed at the front by a diaphragm 14, behind which a pressure stamp 15 is mounted in this embodiment. This may include a frontal acting on the diaphragm 14 pressure on the measuring element 3 übertra ^¬ gene, as shown in FIG. 1 by arrows. Other constructions are also possible. Radially outside the housing 2 is a clamping device 4>. arranged with two opposite, transverse to the axial direction surfaces 5, 6. For mounting a clamping sleeve 8 is provided, which clamps the clamping device 4 to a component 9 in the mounted state. In this case, the clamping device 4 is supported on its first surface 5 on a shoulder 10 of the component 9 and is pressed against its second surface. che 6 of the clamping sleeve 8, which is bolted to the component 9, clamped. The surface 6 corresponds in this arrangement no cutting surface, since this part of the jig 4 is connected to the clamping sleeve 8. However, the theoretical ¹ surface 6 defines the end of the clamping device ^'. 4

According to the invention, the clamping device 4 is tubular between the two surfaces 5, 6 and comprises two parts 4a, 4b, each of which must be axially much longer than its wall thickness. As a result, a radial force, which is introduced from the component 9 via one of the surfaces 5, 6 into the parts 4a, 4b of the clamping device, is not transmitted radially. In addition, the clamping device 4 is located towards a radial distance to the part 9, and with the common housing 2 only at its central portion by a schma ^¬ len web 7 is connected, so that the chuck 4 in use either an axial or a radial stress from the component 9 transmits to the housing 2. As a result, an incorrect measurement of the measuring element 3 is prevented. Decisive in this arrangement is that in the region of the web 7 and in the entire region of the clamping device 4, which extends axially on both sides of the web 7 over the long, tubular parts 4a, 4b, an annular gap 18 in the axial direction to the component .9 is provided , The housing 2 is preferably spaced except in the region of the web 7 and the cable guide 12 to all other components 4, 8, 9 are arranged.

Deformation can thus reach the housing 2 via the component 9 only at the end regions via the surfaces 5, 6 via the two parts of the clamping device 4a, 4b and via the web 7. The two parts of the clamping device 4a, 4b on both sides of the web 7 act as a spring, because they are designed long, in contrast to their radial wall thickness WE.

The axial length LE of the clamping device 4 should in the optimal case at least five times, preferably at least ten times as large as the wall thickness WE in the tubular region.

The wall thickness WE of the clamping device 4 in the tubular region 4a, 4b should preferably be at least three times, preferably at least five times, smaller than the wall thickness WG of the housing 2 in the region of the measuring element 3. This ensures that the clamping device 4 is much softer than the housing , whereby less radial forces are transferred.

The web 7 is axially comparatively short (LS) with respect to the axial length LA of the recess 11 in the housing 2 for the measuring element 3 and with respect to each of the tubular parts 4a, 4b of the clamping devices. The aspect ratio should be at least 1: 2, preferably at least 1: 4. This prevents axial distortions from the component 9 from being transmitted to the measuring element 3.

Preferably, the web 7 is integrally connected to the housing 2. But this is' not mandatory, because the bridge 1 can also be designed as a ring attached or attached.

In addition, the web 7 with one or both of the adjoining parts of the clamping device 4a, 4b may be integrally connected to one or both of the support surfaces 5, 6. In Fig. 7, the web 7 with the part 4a of the jig and the support surface 5 is integrally connected. Accordingly, the clamping sleeve 8 with the adjacent tubular part 4b of the clamping device integrally connected to its clamping surface 6.

It could also, as not shown here, both parts of the clamping device 4a, 4b with the web 7 in one piece and in any case this in turn be integrally connected to the housing 2.

As shown in Fig. 7, the web 7 is attached to the front end of the housing 2. Thus, the sensor 1 is a front-sealing sensor and the support surface 5 is the front-most front of the sensor 1.

FIG. 8 shows another embodiment of a sensor 1 according to the invention. In contrast to the embodiment in Fig. 7, this embodiment is shoulder-sealing. Its front region of the sensor housing 2 is surrounded by a gap axially outward, and the web 7 is set back from the front end of the housing 2.

Otherwise, this embodiment differs in Fig. 8 from that in Fig. 7, that the part 4a of the jig is a ring which is not connected to the web 7. Likewise, the part 4b of the clamping device could be designed with a clamping surface 6 as a ring and not be integrally connected to the clamping sleeve 8.

FIG. 9 shows a further arrangement of a shoulder-sealing sensor 1 according to the invention. This largely corresponds to the embodiment in Fig. 8, wherein the ring is designed as part 4a of the jig axially longer and protrudes frontally over the region of the housing 2. In the axial direction in front of the sensor 1, a heat shield 13 is also attached to reduce the heat input to the sensor. The arrangements according to the invention in FIGS. 7-9 are all distinguished by a deformation-decoupled clamping with a clamping device 4, which can transmit neither radial nor axial deformations or stresses. In particular, such sensors 1 according to the invention can be designed as pressure, force or acceleration sensors, preferably with piezoelectric measuring elements 3. Advantageously, these sensors 1 are heat-resistant for measuring processes in combustion chambers of internal combustion engines, in particular in cylinder heads.

Further advantages can be achieved by the clamping device 4 is provided with means 19, 20, 21, which increases their radial mobility. It therefore becomes radially softer and thus transmits less stress to the sensor. Examples are set forth in FIG. Fig. 10a shows the clamping device 4, without web 7, which would be mounted approximately centrally, in its original form.

FIGS. 10 b and c show two radially movable variants, where ^¬ the mobility is provided by internal annular gaps 19. In FIG. 10d, the radial mobility is achieved by means of two regions 20 designed to be tapered. The large bearing surfaces 5, 6 remain in these variants of FIG. 10 bd obtained. In FIGS. 10e and 10f, the abutment surface 5 and the clamping surface 6 are reduced by bends or rounded portions 21 of the bearing surfaces, as far as rolling versions with rounded surfaces 5, 6. These versions are particularly suitable for hard mounting locations.

All these variants can be combined with each other. By increasing the radial mobility of such clamping devices 4, they can be made shorter in order to still perform the same function of decoupling. LIST OF REFERENCE NUMBERS

1 sensor

2 housings

3. measuring element

4 clamping device

4a, 4b: tubular parts of the clamping device

5 First surface of the clamping device, supporting surface

6 Second surface of the clamping device, clamping surface

7, footbridge

8 clamping sleeve

9 component

10 paragraph

11 recess

12 cable guide

13 heat shield

14 membres

15 plunger

16 mounting thread

17 channel

18 annular gap

19 inside annular gap

20 Rejuvenation zone of the clamping device

21 Bending or rounding of the bearing surfaces

LE Axial length of the clamping device

LS Axial length of the bridge

LA Axial length of the recess

WE Wall thickness of the clamping device

WG wall thickness of the housing

Claims

claims

1. Sensor with an axial alignment comprising a housing (2) with a measuring element (3) in a recess (11) and a radially outside of the ^' housing (2) arranged clamping device (4) with two opposite, transverse to Axial direction extending surfaces (5, 6) and a clamping sleeve (8) for mounting the Einspannvor- direction (4) to a component (9), wherein the clamping device (4) in the mounted state on its first surface (5) on a paragraph ( 10) of the component (9) is supported and clamped on its second surface (6) ^' by the clamping sleeve (8), which is screwed to the component (9), characterized in that the clamping device (4) between the two surfaces (5, 6) is tubular and the component (9) arranged radially spaced by an annular gap (18) and a ^¬ zig in its central region by a narrow web (7) 'with the housing (2 ) connected is.

2. Sensor according to claim 1, characterized in that the axial length LE of the clamping device (4) at least five times, preferably at least ten times as large as the wall thickness WE in the tubular region.

3. Sensor according to claim 1 or 2, characterized in that the wall thickness WE of the clamping device (4) in the tubular portion (4a, 4b) at least three times, preferably at least five times smaller than the wall thickness WG of the housing (2) in the region of the measuring element (3).

4. Sensor according to one of the preceding claims, characterized in that the axial length LS of the web (7) at most half as large, preferably at most a four ^¬ tel is as large as the axial length LA of the recess (11) in the housing (2 ) for the measuring element (3).

5. Sensor according to one of the preceding claims, characterized in that the axial length LS of the web (7) at most half as large, preferably at most a four ^¬ tel is as large as the axial length of each of the rohrför- shaped parts 4a, 4b jigs.

6. Sensor according to one of the preceding claims, characterized in that the housing (2) except in the region of the web (7) and the cable guide (12) spaced from other components (4, 8, 9) is arranged.

7. Sensor according to one of the preceding claims, characterized in that the web (7) with the housing (2) is integrally connected.

8. Sensor according to one of the preceding claims, characterized in that the web (7) with one or both of the adjoining parts of the clamping device (4a, 4b) with one or both of the Abstützflachen (5, 6) is integrally connected.

9. Sensor according to one of the preceding claims, characterized in that the clamping sleeve (8) with the adjoining tubular part of the clamping device (4b) is integrally connected to its clamping surface (6).

10. Sensor according to one of the preceding claims, characterized in that the web (7) at the front end of the housing (2) is mounted to provide a front-sealing sensor. Sensor according to one of the preceding claims, characterized in that the web (7) is set back from the front end of the housing (2) ^' to provide a shoulder-sealing sensor.

Sensor according to one of the preceding claims, characterized in that in the axial direction in front of the sensor, a heat shield (13) is mounted in order to reduce the heat supply to the sensor.

Sensor according to one of the preceding claims, characterized in that the sensor is a pressure, force or acceleration sensor, in particular a piezoelectric sensor.

Sensor according to one of the preceding claims, characterized in that the sensor is heat-resistant ^{ausgestal ¬} tet for measuring operations in combustion chambers of internal combustion engines, in particular in cylinder heads.

Sensor according to one of the preceding claims, characterized in that the clamping device (4) has means (19, 20, 21) which increase the radial mobility of the clamping device.