Abstract
An ultrasonic transducer for an ultrasonic flowmeter includes a piezoelectric transducer element arranged between first and second holding elements. The first holding element, the piezoelectric transducer element and the second holding element are arranged one behind the other along a longitudinal axis of the ultrasonic transducer. The pre-tensioning element is on the side of the first holding element facing away from the piezoelectric transducer element. A connecting element is on the side of the pre-tensioning element facing away from the first holding element. The connecting element serves to preload the pre-tensioning element and is connected to the second holding element. In the loaded state of the pre-tensioning element, a force acts on the first holding element and, via the connecting element, on the second holding element in such a way that the first holding element and the second holding element clamp the piezoelectric transducer element.
Claims
1. An ultrasonic transducer for an ultrasonic flowmeter, comprising: at least one piezoelectric transducer element; a first holding element; a second holding element; wherein the at least one piezoelectric transducer element is arranged between the first holding element and the second holding element; wherein the first holding element, the at least one piezoelectric transducer element and the second holding element are arranged one behind the other along a longitudinal axis of the ultrasonic transducer; wherein at least one pre-tensioning element is provided on the side of the first holding element facing away from the piezoelectric transducer element; wherein a connecting element is provided on the side of the pre-tensioning element facing away from the first holding element, wherein the connecting element serves to preload the pre-tensioning element and is connected to the second holding element; and wherein, in the loaded state of the pre-tensioning element, a force acts on the first holding element and, via the connecting element, on the second holding element in such a way that the first holding element and the second holding element clamp the at least one piezoelectric transducer element.
2. An ultrasonic transducer according to claim 1, wherein the pre-tensioning element is designed in the first holding element; and pre-tensioning element is implemented by a material reduction of the first holding element.
3. The ultrasonic transducer according to claim 1, wherein the pre-tensioning element is designed as a compression spring, disc spring, wave spring or plate spring.
4. The ultrasonic transducer according to claim 1, wherein at least one second pre-tensioning element is provided; wherein the first pre-tensioning element and the second pre-tensioning element are arranged adjacent to one another in the direction of the longitudinal axis of the ultrasonic transducer; and wherein the first pre-tensioning element and the second pre-tensioning element are designed identically.
5. The ultrasonic transducer according to claim 1, wherein the connecting element is implemented by a sleeve; and wherein the sleeve can be connected to the second holding element via additional fastening elements or the sleeve can be screwed onto the second holding element, so that the pre-tensioning element is brought into the loaded state by the latching or by the screwing on of the sleeve.
6. The ultrasonic transducer according to claim 1, wherein the connecting element is designed in a T-shape with a T-roof and a T-bar; wherein the T-shaped connecting element has a thread at end of the T-bar facing away from the T-roof; wherein the second holding element has a connecting-element receptacle with a corresponding mating thread; wherein the pre-tensioning element, the first holding element and the at least one piezoelectric transducer element each have a recess through which the T-bar of the T-shaped connecting element is passed; and wherein the pre-tensioning element is brought into the loaded state by screwing the T-shaped connecting element into the second holding element.
7. The ultrasonic transducer according to claim 1, wherein the connecting element is implemented by a connecting rod and a nut; wherein the connecting rod is connected to the second holding element; wherein the pre-tensioning element, the first holding element and the at least one piezoelectric transducer element each have a recess through which the connecting rod is passed; wherein, at an end facing away from the second holding element, the connecting rod has a thread onto which the nut can be screwed; and wherein the pre-tensioning element is brought into the loaded state by screwing the nut onto the connecting rod.
8. The ultrasonic transducer according to claim 7, wherein the connecting rod is welded to the second holding element or is designed integrally with the second holding element.
9. The ultrasonic transducer according to claim 7, wherein the connecting rod is detachably connected to the second holding element by a screw connection, a snap-in connection or a bayonet connection.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] In detail, there are now a large number of possibilities for designing and further developing the ultrasonic transducer according to the invention. In this regard, reference is made to the description of particularly preferred embodiments in conjunction with the drawings.
[0025] FIG. 1 illustrates an external view of a first variation of an ultrasonic transducer.
[0026] FIG. 2 illustrates a sectional view of the ultrasonic transducer shown in FIG. 1.
[0027] FIG. 3 illustrates a sectional view of the first holding element of the ultrasonic transducer shown in FIG. 2.
[0028] FIG. 4 illustrates a sectional view of a second variation of an ultrasonic transducer.
[0029] FIG. 5 illustrates a sectional view of a third variation of an ultrasonic transducer.
[0030] FIG. 6 illustrates a sectional view of a fourth variation of an ultrasonic transducer.
[0031] FIG. 7 illustrates a sectional view of a fifth variation of an ultrasonic transducer.
DETAILED DESCRIPTION
[0032] FIG. 1 shows an external view of an ultrasonic transducer 1 for an ultrasonic flowmeter. The ultrasonic transducer 1 has at least one piezoelectric transducer element 2. In the illustrated embodiment, the ultrasonic transducer 1 has a total of six piezoelectric transducer elements 2. In addition, the ultrasonic transducer 1 has a first holding element 3 and a second holding element 4, wherein the piezoelectric transducer elements 2 are arranged between the first holding element 3 and the second holding element 4. The first holding element 3, the piezoelectric transducer elements 2 and the second holding element 4 are arranged one behind the other along a longitudinal axis 5 of the ultrasonic transducer 2. On its side 6 facing away from the piezoelectric transducer elements 2, the first holding element 3 has a pre-tensioning element 7. On the side 8 of the pre-tensioning element 7 facing away from the first holding element 3, a connecting element 9 is provided. The connecting element 9 serves to load the pre-tensioning element 7 and is connected to the second holding element 4. The connection of the connecting element 9 and the second holding element 4 is not visible in FIG. 1, but is apparent in the sectional view through the ultrasonic transducer of FIG. 1 shown in FIG. 2.
[0033] FIG. 2 shows a sectional view through the ultrasonic transducer 1 of FIG. 1. The pre-tensioning element 7 is loaded by the connecting element 9. In the loaded state, which is shown in FIG. 2, a force F acts on the first holding element 3 and via the connecting element 9 on the second holding element 4 in such a way that the first holding element 3 and the second holding element 4 clamp the piezoelectric transducer elements 2. In FIG. 2, the acting forces are indicated by force arrows. Due to the fact that the pre-tensioning element 7 strives to go into its relaxed state, a force F acts on the connecting element 9. An opposite force F acts on the first holding element 3. The force acting on the connecting element 9 is transmitted to the second holding element 4 due to the connection of the connecting element 9 and the second holding element 4. In the area of the piezoelectric transducer elements 2, a force F thus acts on the second transducer element, which strives to pull the transducer element upwards, and an opposite force F acts on the second holding element 3, which strives to pull the holding element 3 downwards. Accordingly, the piezoelectric transducer elements 2 are clamped between the first holding element 3 and the second holding element 4.
[0034] In the illustrated embodiment of FIG. 2, the pre-tensioning element 7 is designed in the first holding element 3. The first holding element 3 of FIG. 2 is also shown in sectional view in FIG. 3. The first holding element 3 is cylindrical in overall shape. In its upper region, namely on the side 6 facing away from the piezoelectric transducer elements 2, the second holding element 4 has a material reduction. This implements a pre-tensioning element 7 in the form of a spring element. The wall thickness of the first holding element 3 is significantly reduced in the upper region 6, and the first holding element 3 is compressible in this upper region 6 in the longitudinal direction 5 of the ultrasonic transducer 1.
[0035] In the further figures, the pre-tensioning elements 7 are shown in alternative embodiments. In FIG. 7, for example, the pre-tensioning element 7 is implemented by a compression spring 11. In FIG. 5, the pre-tensioning element 7 is implemented as a disk spring 12. FIG. 6 shows an illustration in which the pre-tensioning element 7 is designed as a plate spring 13. FIG. 6 also shows that the ultrasonic transducer 1 has a second pre-tensioning element 14. This pre-tensioning element 14 is also implemented as a plate spring 13. The first pre-tensioning element 7 and the second pre-tensioning element 14 are arranged adjacent to each other, but spaced apart from each other, along the longitudinal axis 5 of the ultrasonic transducer 1.
[0036] The figures also show various designs of the connecting element 9. In the embodiment shown in FIG. 4, the connecting element 9 is implemented by a sleeve 15. The sleeve 15 is connected to the second holding element 4 via a screw connection 16. For this, an internal thread 17 is designed on the sleeve 15 and a corresponding external thread 18 is designed on the second holding element 4. The sleeve 15 is screwed onto the second holding element 4. Screwing on compresses the pre-tensioning element 7, which in the embodiment shown is implemented as a compression spring 11. In alternative embodiments not shown, the sleeve 15 can be snapped onto the second holding element or, for example, connected to the second holding element with additional fastening elements in the form of screws.
[0037] FIG. 5 shows a further embodiment of an ultrasonic transducer 1 with an alternative connecting element 9. In the embodiment shown, the connecting element 9 is implemented in a T-shape and has a T-roof 19 and a T-rod 20. At its end 21 facing away from the T-roof 19, a thread 22 is designed on the T-rod 20. The second holding element 4 has a connecting element receptacle 23 with a corresponding mating thread 24, so that the T-bar 20 can be screwed into the connecting element receptacle 23. Both the pre-tensioning element 7 and the first holding element 3 and the piezoelectric transducer elements 2 each have a recess 25 through which the T-bar 20 of the T-shaped connecting element 9 is passed. By screwing the T-shaped connecting element 9 into the second holding element 4, the pre-tensioning element 7 is brought into the loaded state.
[0038] Further embodiments of the connecting element 9 are implemented in FIG. 6 and FIG. 7. In FIG. 6 and also in FIG. 7, the connecting element 9 is implemented by a connecting rod 26 and a nut 27. The connecting rod 26 is connected to the second holding element 4. Also in this embodiment, the pre-tensioning element 7, the first holding element 3 and the piezoelectric transducer elements 2 each have a recess 25 through which the connecting rod 26 is guided. At its end 28 facing away from the second holding element 4, the connecting rod 26 has a thread 29 onto which the nut 27 can be screwed. Screwing the nut 27 onto the connecting rod 26 brings the pre-tensioning element 7 or, in the design shown in FIG. 6, the pre-tensioning elements 7 and 14, into the loaded state.
[0039] In FIG. 6, the connecting rod 26 is non-detachably connected to the second holding element 4, namely in the embodiment designed integrally with the second connecting element 4. In contrast, in the embodiment of FIG. 7, the connecting rod 26 is detachably connected to the second holding element 4. In the example shown, this is implemented by a screw connection 30. Further possibilities not shown are, for example, snap-in connections or bayonet connections.
