JPS61104236A - Pressure sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is based on the effect of pressure? It has a pressure sensitive element (resistance element, thick film resistor, piezoresistive element or piezoelectric element) that changes the properties of the Jt element, and a carrier that supports the pressure sensitive element and its 1u air conductor, and is partitioned by a wall. The present invention relates to a pressure sensor for detecting the pressure of Ixffi, in particular for measuring the combustion pressure in diesel or gasoline engines or for measuring the pressure of a distribution pump for fuel supply.

rPrior Art] Such a pressure sensor is known from German Patent Application No. 31 25 640 and uses a carrier which supports a pressure-sensitive element, i.e. a membrane resistor, and which is arranged at the pressure space side end of the component. Contains. The carrier forms a bushing containing a sealing compound of insulating material, on which is a pressure-sensitive membrane resistor, and suitable electrical conductors are passed through this bushing. A problem with such pressure sensors is that the encapsulating compound does not have the necessary mechanical strength so that it can also be used as a carrier for the membrane resistor, and furthermore, it is difficult to connect the pressure sensitive element to the pressure medium without isolating it. It is not always desirable to provide the pressure-sensitive element directly adjacent, on the other hand, it is expensive and often It is also known to completely separate the pressure-sensitive element from the pressure medium by providing a breakable membrane structure, which membrane structure insulates the pressure-sensitive element from the pressure medium. However, in this case, apart from the membrane material itself,
Complex measures are required to permanently support and hold the membrane.

[Problem that the invention seeks to solve]

The problem underlying the invention is therefore to provide a pressure sensor which can be used for the detection of high pressures that are particularly inexpensive and dynamically acting, and which avoids effects or damage due to the effects of the pressure medium itself.

Means for Solving Problem C] In order to solve this problem, according to the present invention, the carrier forms a cavity in the form of a blind hole closed to the material in which the pressure is detected; Inside the chamber, a pressure-sensitive element is provided in contact with the bottom of the cavity from the inside.

〔Effect of the invention〕

In particular, the pressure sensor according to the invention does not suffer from substantial deflection or deformation under the action of the pressure medium.

Pressure detection can be carried out due to the elastic deformation that occurs as a whole of the entire front part of the body, and the pressure-sensitive element for detecting the effect of pressure is completely enclosed in the inner cavity of the carrier, which is isolated on its entire surface from the pressure medium. The structure and function of the pressure sensor are extremely durable and particularly durable.

Therefore, the pressure-sensitive element is accommodated and surrounded by a recess configured like a blind hole in the carrier, but since it is held fixedly against the bottom of the carrier, in any case it acts on the bottom of the carrier. The elastic deformation caused by the deformation of the wall portion with the bottom can be detected and converted into an electrical signal.

Advantageous developments and improvements of claim 1 are subject to the dependent claims. Of particular interest is an arrangement in the form of a screw passing through the wall surrounding the pressure medium, which screw itself accommodates a further insert for pressing a pressure-sensitive thick-film resistor or other pressure-sensitive element into its inner screw base. , this insert piece can preferably be screwed into the screw.

In particular, according to claims 17 to 21:
Pressure measurement is possible if the walls of the container or conduit are not thick enough to form a blind hole. This allows the pressure sensor to be used even in thin-walled containers or conduits.

In this way, the pressure sensor can be attached without changing the structure.

〔Example〕

An embodiment of the invention is shown in the drawing and will be described below.

According to the basic idea of the invention, the pressure-sensitive element is completely enclosed by the carrier part and placed adjacent to the medium in which the pressure or pressure change is to be measured, and the elasticity of the carrier in the transition region is utilized, so that the pressure-sensitive element 1 in the blind hole-like containment range of the carrier
′! ? 11rt, but also held fixed due to its deformability.

The drawing shows a part of the wall adjacent to the pressure medium! It is indicated by the reference numeral 14. The medium in which the pressure or pressure change is to be measured is shown at 6 below in the drawing. Other elements can also be used here, such as pins or possibly part of the wall 14 of the pressure vessel, as will be explained below.

In the embodiment shown in the drawings, the carrier 1 corresponds to the wall 14 of the pressure vessel.
The lower region of the carrier 1 which is in contact with the pressure medium 16 extends into the wall 14, at least until the bottom 4 of the carrier 1 is in contact with the pressure medium gI+6. In other words, if the carrier I is in any case a separate part, the hole 14a in the wall accommodating the carrier 1 must be constructed in such a way that tii.

The carrier 1 is preferably screwed into a receiving hole, so that this hole has an internal thread and the carrier itself has an external thread. There is a blind hole 17 terminating as flat as possible in the bottom 4 inside the carrier l, so that a bottom 4 remains with a predetermined thickness a, as shown in the drawing.

If desired, the lower part of the carrier l! beyond i\14 by a predetermined distance @b into the volume enclosed by the wall 14, so that the elasticity of the carrier l in the lower region is
Enhanced by large cantilevers.

From the inside, a pressure-sensitive element 6 adjoins the bottom 4 and thus the bottom of the blind hole 17, optionally or preferably after the interposition of a temporary 5 made of an elastic material (plastic or gold V4) which transmits the effect of pressure. As will be described later, the pressure sensitive element 6, which is a thick film resistor in the drawings, is pressed against the inner bottom surface or the intermediate plate 5, and in any case, it is pressed with a predetermined pressing force that does not change with pressure fluctuations. This pressing force is applied to the supporting, pressing or holding member 7.
is generated by This holding element is itself U-shaped and can be screwed at 18 into the upper internal thread of the deep hole 17 of the carrier l.

The thick-film resistor or generally the pressure-sensitive element 6 itself is provided on an insulating material 8 as an intermediate part made of glass, ceramic or plastic, for example printed in the case of thick-film resistors, the intermediate material 8 being provided with wires contained therein. It also accommodates penetrations and electrical connection pieces 9. For the mechanical edging, the intermediate material 8 can be surrounded by a metal ring 10 which rests downwards on the plate 5 or is slightly bent against it, so that the lower region of the carrier (bottom 4 and height b) The elastic deformation of the exposed wall) is unaffected and can only be detected by the pressure-sensitive element 6. In any case, the holding member 7 presses at least the elements 6 and 8, possibly together with the elements 9 and lO, against the plate 5 or the bottom 4, constantly applying a predetermined pressing force, and at the same time has the electrical connection piece 9 and The electrical connection piece 9 which is designed to accommodate 12 and which leads upward from the pressure-sensitive element 6 can be welded or soldered to the electrical connection piece +2 which leads to the outside in an intermediate region, for example at 13. .

The retaining element 7 is of cylindrical construction and makes it possible to fill its interior space II with elastic material after assembly, so that good strain relief of the connecting cable and adequate protection of the underlying components take place.

The functions of such a pressure sensor are as follows. When the carrier ivy is screwed into the hole 14a of the pressure vessel Iji 14,
The resulting pressure causes an elastic deformation of the bottom 4 of the carrier 1 and of the tube 9+5 in the pressure region while the carrier 1 is moving. This elastic deformation can exert a force on the pressure-sensitive element 6, which can be a membrane resistor or a quartz plate, and the effect of this force is used for force measurement. This is because the electrical properties of the pressure sensitive element 6 change accordingly.

It is clear that the pressure-sensitive element 6 must be kept free pressed against the bottom 4 (or the intermediate plate 5), which means the following. That is, the holding member 7, the metal ring 10. and the other parts involved in the generation of the pressing force for the pressure-sensitive element 6 are arranged at a distance from the inner wall of the carrier, so that the former does not move together with the latter or 4tE8: does not deform and in any case the forces acting are must be detected through the ay film resistance.

With such a carrier, preferably thread-like, in which a thread-like holding element is accommodated in its blind hole, a very simple and particularly durable construction of a pressure sensor is realized, which makes use of the deflection of the membrane to obtain the measurement result. There's no need. The total elastic deformation of the front part of the carrier 1 serves to generate the measurement signal, and even with a relatively large bottom thickness a, the pressure changes are relatively large, for example, and the elastic shortening of the carrier 1 in the area 15 of the annular wall holding the bottom 4 Even better measurement results can be obtained when this is also carried out.

Such pure elastic deformation is easier to use than membrane configurations in terms of strength and virtually never ages. Such pressure sensors are therefore preferably used for pressure measurements in distribution pumps of fuel injection systems and for combustion pressure measurements in diesel or gasoline engines.

As already mentioned above, in some cases the area of the wall 14 itself can be used as a carrier.

in this case! ! A blind hole is drilled into 214 from the outside, so that only a small bottom area remains from the top in the drawing. This bottom region guarantees sufficient strength for normal operation of the device, but also has sufficient elasticity to hold the retaining member 7 apart from the other elements 5.6.
．． When screwing together with 8 and 9 into this wall-side blind hole, the elastic deformation of the wall bottom can be used for pressure measurement and electric signal generation. Since there is no wall area projecting into the pressure space in this case, the remaining elastic deformation of the bottom can be used for pressure measurement. FIG. 2 shows a variant of the embodiment.

The same parts are again indicated by the same numbers. There is a scraped part 26 on the outer wall 25 of the 6ci holding member 7, and its area and carrier l
An insulating layer 28 is provided on the end surface 27 of the holding member 7 that is closer to the bottom 4 of the holding member 7 .

A pressure sensitive thick film resistor 29 and its connecting strip 30 are printed and baked onto this insulating layer. Second absolute @fjJ33
The thick-film resistor 29 and its connecting strip 30 are covered by the thick-film resistor 29 and its connecting strip 30 . This connecting strip rests on the bottom 4 of the carrier l for pressure transmission. Both insulating layers 28, 33 are made using known thick film technology. The anti-oxidant layer 28 is typically made of glass with a wafer-coated copper substrate. The same goes for the second insulating layer 33. Gau 81E Eha Puu 7 Chitsuku Mayo. Yo
t varnish is used. By applying thick film technology, pressure sensors can be manufactured very inexpensively. The electrical connection frame 12 is pulled out from the internal space 11 of the holding member 7 through the hole 34 and connected to the connection strip 3.
It is soldered to 0.

FIG. 3 shows a second modification of the embodiment. The end 35 of the holding element 7, which is closer to the bottom 4 of the carrier 1, is turned and has a short projection 36. As in the variant shown in FIG.
The lIJ 2B, 33 and the thick film resistor 29 are provided in a layered manner. The electrical connection piece 12 is introduced into the interior space I+ of the holding element 7 via the two holes 37,38. What should be noted in both variants is that the soldering points between the electrical connection piece I2 and the connection strip 3o are protected. This must not damage the screwing of the holding element 7 into the blind hole 2 of the carrier 1. The holding element 7 is arranged in a blind hole 2 of the carrier 1, protected from pressure spaces, so that the electrical connection piece 1
2 is placed in the hole 34, 37, 38 without being sealed.

FIG. 4 particularly shows an embodiment of a thin-walled carrier. Holding member 7a, for example, a nozzle holder, has a vertical hole 4) in the center of the dowel.
is configured. Parallel to this longitudinal hole 4) there is a small diameter hole 43 in the wall of the holding element 7a. This hole 43
is provided as close as possible to the outer wall of the holding member 7a,
Helps guide pressure. The pressure sensitive element 6a is in contact with the wall of the holding member 7a within the range of the hole 43 on the outside of the holding member 7a. This pressure sensitive element can be constructed in the same manner as described in FIGS. 1, 2 and 3. The pressure sensitive element 6a is attached to the holding member 7a by a ring 44. Furthermore, the ring 44 is necessary to generate a reaction force when the pressure sensitive element 6a is pressed. Although not visible in FIG. 4, a slit can be cut in the ring 44 and fixedly attached to the holding member 7a by means of a tension screw. Furthermore, the ring 44 can be provided with a female thread so that it can be screwed onto the holding member 7a.

Of course, a different arrangement of the pressure-sensitive elements 6a on the ring 44 is also conceivable. It is also possible to screw the protrusion 45 of the pressure sensitive element 6a into the hole 46 of the gou 44, or to accommodate the pressure sensitive element 6a in a small recess provided inside the J+244.

A modification of the embodiment according to FIG. 4 is not shown in FIG. Here, a recess 47, for example, a cut-out portion, is formed in the outer wall of the holding member 7a, and the pressure-sensitive element 6a is provided in the recess 47. Thereby, the wall thickness between the pressure-sensitive element 6a and the pressure-guiding hole 43 can be reduced, and the pressure-sensitive element 6a can be attached to the holding member 7a. In this case, 1I44 is unnecessary.

However, 5144 further holds the pressure sensitive element 6a in place and protects it from mechanical damage.

The purchase according to FIGS. 4 and 5 is especially true for the injection valve pressure rB
It turned out to be very advantageous.

All features indicated in the description, the claims and the drawings are important for the invention individually or in any combination.

4 Description of the drawings Figure 1 is an elevational view with half cut away of the carrier which supports the pressure sensitive element and is fitted into the wall containing the pressure 11x material;
3 and 3 are respectively cross-sectional views of the river stone of a modification of the embodiment shown in FIG. 1, and FIGS. 4 and 5 are 11' of another embodiment, respectively. FIG.

l...Carrier, 4...bottom, 6.6a, 29...
Pressure sensitive element, 12... Electrical conductor (electrical connection piece), i6.
...Pressure medium, 17...Vacancy (blind hole), 2o...Pressure sensor, 43...Space.

Claims (1)

[Scope of Claims] 1. A pressure-sensitive element that changes electrical properties under the action of pressure, and a carrier that supports the pressure-sensitive element and its electrical conductor,
For the detection of pressure in a medium delimited by walls, the carrier (l) forms a cavity (17) in the form of a closed blind hole with respect to the medium whose pressure is to be detected, in which a pressure-sensitive A pressure sensor characterized in that the element (6) is provided in contact with the bottom of the cavity from the inside. 2. Pressure sensor according to claim 1, characterized in that the pressure-sensitive element is pressed from the inside against the carrier bottom (4) by means of a holding element (7). 3. An intermediate plate (5) made of an elastic material that transmits pressure between the inner surface of the bottom (4) of the carrier (1) and the pressure-sensitive element (6).
The pressure sensor according to claim 1 or 2, characterized in that the pressure sensor is provided with: 4 The pressure-sensitive element (6) is provided on an insulating intermediate material (glass, ceramic, plastic 8), pressed onto this in the case of a thick-film resistor, and the intermediate material (8) is provided with an electrical connection piece (8) to the pressure-sensitive element. 9) The pressure sensor according to claim 1, characterized in that it also accommodates a pressure sensor. 5. Pressure sensor according to claim 1, characterized in that the intermediate material (8) is mechanically bordered by a surrounding metal ring (10). 6. characterized in that the holding member (7) is screwed into the carrier (l) as much as possible to exert a predetermined pressing force on the pressure-sensitive element (6) via the intermediate material (8); A pressure sensor according to claim 2. 7 The holding member (7) and the metal ring (10) are made of one piece, and the intermediate material (8) with the electrical connection piece (9) and the pressure sensitive element (6) is directly attached to the lower end of the holding member (7). Pressure sensor according to claim 5, characterized in that it is attached. 8 The carrier (l) is arranged in such a way that the bottom part (4) of the carrier (l) deforms elastically under the applied pressure and this deformation influences the pressure-sensitive element (6) which is independently assisted and supported by the holding member. 3. Pressure sensor according to claim 2, characterized in that at least the bottom part (4) of the pressure sensor 10 is formed by a pressure sensor. 9 The carrier (l) is a threaded member, and the receiving hole (
Claim 1, characterized in that the carrier annular wall region (15), which is screwed into 14a) and projects inwardly into the pressure space, is also elastically deformed in addition to the bottom (4) of the carrier (l). Pressure sensor described in section. 10 that the holding element (7) is configured as a hollow screw that can be screwed into the blind hole (17) of the carrier (l), the inner cavity (11) of which is filled with elastic material after assembly and introduction of the electrical conductor; A pressure sensor according to claim 1, characterized in that: 11. A blind hole-like cavity closed to the pressure medium is formed by the wall (14) of the pressure vessel accommodating the pressure medium, into which the retaining member (7) is screwed with its upper part (externally). The pressure sensor according to claim 1, characterized in that: 12. The pressure sensor according to claim 1, characterized in that the holding member (7) is provided apart from the carrier (l) at least in the range of elastic deformation of the carrier (l). 13 The insulating intermediate material (28), the pressure-sensitive element (29) and the second insulating layer (33) are layered using thick film technology on the carrier (l
) of the retaining member (7) closer to the bottom (4) (
27), and the second insulating layer (33) is provided on the bottom (4).
The pressure sensor according to claim 4, characterized in that the pressure sensor is in contact with. 14. Claims characterized in that the electrical connection piece (12) for the pressure-sensitive element (29) is led into the cavity (11) of the holding element through the hole (34, 37, 38) 13th
Pressure sensor described in . 15 The outer wall (25) of the holding member (7) is formed with a recess (26), in the area of which the connection strip (30) of the pressure-sensitive element (29) and its electrical connection piece (12) are connected. 11. Pressure sensor according to claim 10, characterized in that they are connected to each other. 16 The end (35) of the holding element (7), which is closer to the bottom (4) of the carrier (l), has a protrusion (36) on which an insulating intermediate material (28) is applied in a layer using thick film technology. 11. Pressure sensor according to claim 10, characterized in that a pressure sensitive element (29) and a second insulating layer (33) are provided. 17 In a device that detects the pressure of a medium partitioned by walls, it has a pressure-sensitive element that changes electrical properties under the action of pressure, and a carrier that supports the pressure-sensitive element and its electrical conductor, and the carrier (7a) space for the medium whose pressure is detected (4
3), characterized in that the pressure sensitive element (6a) is provided in direct contact with the wall of the space (43) from the outside. 18. Pressure sensor according to claim 17, characterized in that the pressure-sensitive elements (6a) are arranged on the wall of the space (43) at as little distance as possible. 19. The pressure sensitive element (6a) is provided in a notch (47) formed in the wall of the space (43),
A pressure sensor according to claim 17. 20. Pressure sensor according to claim 17, characterized in that the pressure-sensitive element (6a) is mounted on the carrier (7a) by means of a mounting element (44). 21. Pressure sensor according to claim 17, characterized in that the carrier (7a) is part of an injection valve.