JP2015213242A - Pressure compensation type converter assembly and acoustic converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure compensation type converter assembly for housing a piezoelectric converter that adjusts an internal pressure depending on a change in an external pressure.SOLUTION: A pressure compensation type converter assembly includes: an inner housing 4 having a closed converter end part 4a; and an outer housing 6 having an opened converter end part 6a. Ceramic layers 1 and 2 and a backing 3 are provided at the closed converter end part 4a of the inner housing 4. A channel 19 filled with liquid is provided between the outer housing 6 and the inner housing 4, and has a converter end part 19a opened to an environment 20, and a connection end part 19b opened to a first inner space 4c. A blocking member 10 separates the converter end part 19a of the channel 19 from the connection end part 19b to prevent a flow of the fluid between the two end parts. The blocking member 10 can move in the channel 19 depending on a pressure difference between the environment 20 and the first inner space 4c.

Description

Detailed Description of the Invention Background of the Invention It is known to use piezoelectric transducers in downhole drilling environments where high pressures and high temperatures are a challenge for the transducers. In such an environment, the pressure can be 25 Kpsi or higher and the temperature can exceed 600 ° F.

  If the pressure in the environment exceeds the pressure inside the transducer, the performance of the transducer can be degraded. Various mechanisms for adjusting the internal pressure in response to changes in the external pressure have been devised, but none have been completely satisfactory.

  Thus, there is a need for a pressure compensated assembly for housing a piezoelectric transducer or other functional element. The present invention addresses this demand.

SUMMARY OF THE INVENTION According to one embodiment of the present invention, a pressure compensated transducer assembly is provided.

  The assembly preferably includes an inner housing having a closed end and side walls defining a first interior space. The closed end is the end that is distal (distant) from the point of attachment to the operating electronics.

  The assembly also includes an outer housing having an open transducer end and sidewalls and defining a second interior space.

  A functional element that may be a piezoelectric transducer is provided in the first internal space. When the functional element is a piezoelectric transducer, the piezoelectric material is preferably provided as a disk (or disk stack) having a surface that contacts the closed end of the inner wall. A piezo element or piezo stack is positioned within the inner housing such that the piezo element vibrates the housing floor and propagates acoustic waves from the device. The transducer faceplate is preferably provided on the outer surface of the housing floor, in which case acoustic waves are radiated from the transducer faceplate.

  At least a portion of the outer housing is spaced from the inner housing, and a channel is provided in a space between the outer housing and the inner housing, the channel in a first end open to the environment and in the first inner space. And a second end that is open to the front. The end of the channel open to the environment is preferably open to the environment adjacent to the transducer, and more particularly to the environment adjacent to the transducer faceplate.

  The blocking member is provided in the channel and is movable in the channel. The movable blocking member defines a connection end channel portion and a transducer end channel portion.

  A relatively incompressible fluid is provided in the first interior space and extends into the connecting end channel portion toward the blocking member. The relatively incompressible fluid is preferably a liquid, more preferably an oil.

  The movable blocking member is effective to prevent fluid flow from the connecting end channel portion to the transducer channel portion. The movable blocking member is also effective in equalizing the pressure inside the device and the pressure outside the transducer. As the pressure outside the transducer increases, the movable member moves within the channel, and the size (capacity) of the portion of the channel connected inside the device decreases. Since the liquid in the interior and in the channel is relatively incompressible, the internal pressure increases until the pressure is equal and movement of the movable member stops.

  The liquid filled channel preferably does not have the effect of acoustically separating the inner surface of the transducer from the inner surface of the inner housing.

1 is a side view showing a full cross section of one embodiment of a pressure compensated transducer assembly of the present invention. FIG. 6 is a side view showing the entire cross section of another embodiment of the pressure compensated transducer assembly of the present invention.

  For the purpose of promoting an understanding of the principles of the invention, reference will now be made to certain preferred embodiments and specific language will be used to describe the same. Nonetheless, this is not intended to limit the scope of the invention, and substitutions and further modifications to the illustrated apparatus and further applications of the illustrated inventive principles will normally be made by those skilled in the art to which the invention relates. It is understood that it can be considered.

  As indicated above, one embodiment of the present invention provides a pressure compensated transducer assembly that can be used as a sensor in an environment such as a downhole oil well. Such transducers can transmit and receive acoustic waves using piezoelectric material. The assembly is normally connected at one end to the electronic control unit and propagates acoustic waves from the other end. For this purpose, for the purposes of this disclosure, the assembly is described as having a transducer end and a connection end, where the transducer end is the end of the assembly through which acoustic waves propagate to the environment. The connection end is an end connected to the control electronic device.

  In a preferred embodiment, the assembly includes an inner housing, an outer housing, and an inter-housing space between all or part of the two housings. The inner housing preferably includes a closed end and a sidewall and defines a first interior space. The outer housing preferably includes an open end and sidewalls and defines a second interior space. The two housings are preferably positioned such that the inner housing is substantially positioned within the outer housing and the closed end of the inner housing is adjacent to the open end of the outer housing. . In the most preferred embodiment, the shape of the housing is generally cylindrical and the inner housing with closed ends forms a right cylinder (having selectively open ends) against the inner housing sidewall. . The outer housing covers the inner housing and the closed end of the inner housing is positioned at or near the open end of the outer housing.

  The functional element, which can be a piezoelectric transducer, is provided at the closed (transducer) end of the housing in the first internal space. In a preferred embodiment, the transducer includes a piezoelectric disk (or stack, or two or more piezoelectric disks) positioned against the bottom surface of the disk (or disk stack) on the inner floor of the closed housing end. The disk or disk stack may contact the housing floor such that disk / stack vibration causes corresponding housing floor vibration. The piezo element is preferably effective to vibrate at a frequency and power effective to emit acoustic waves suitable for remote sensing in a downhole drilling environment.

  The backing can be placed on top of the disk or disk stack. For example, a high acoustic impedance material such as tungsten may be used. In other embodiments, the backing can be a mixture of high acoustic impedance materials, such as an epoxy / polymer with or without powdered tungsten. A tension rod or other assembly may be provided that maintains the piezo element and backing properly compressed.

  The transducer assembly may include a face plate that contacts adjacent the transducer end of the inner housing. In one embodiment, the faceplate is a thin material that is wear resistant and has an acoustic impedance that is lower than the acoustic impedance of the housing floor. Preferred faceplate materials include polymers such as polyetheretherketone (PEEK). The face plate can be adhered to the outside of the inner transducer housing.

  The disk or disk stack is driven and controlled by electronic equipment attached to the connection surface of the disk or disk stack, as is known in the art.

  As indicated above, the inner and outer housings are preferably cylindrical in shape, and the outer housing is spaced from the inner housing. An inter-housing space is provided between the outer housing and the inner housing, and the space selectively surrounds the entire inner housing or substantially the entire housing. Alternatively, the inner housing space may be one or more channels provided between the inner housing and the outer housing.

  The inter-housing space has a transducer end portion that is open to the environment and a connecting end portion that is open to or connected to the first internal space. The blocking member is provided in the space and is movable in the space. The movable blocking member defines the transducer end portion and the connection end portion of the inter-housing space, and is effective in preventing fluid flow from the connection end to the transducer end or vice versa.

  The liquid is provided in the first internal space and extends to the connection end portion of the inter-housing space. The liquid is preferably an oil such as high temperature silicone oil. The volume of liquid provided in the device is fixed to locate a movable member near (but well within) the transducer end of the inter-housing space at an ambient pressure of about 15 psi. Sufficient to maintain sufficient pressure.

  As the ambient pressure outside the assembly increases (such as when the assembly descends into an oil field), the movable blocking member increases the size / capacity of the transducer end portion of the space and the size of the connecting end portion of the space. It moves in the space between the housings so that the height / capacity becomes small. The space including the connection end portion of the inter-housing space and the space of the inner housing are filled with a predetermined amount of liquid, and the pressure applied by the liquid to the inside of the apparatus increases as the external pressure increases. This compensates for pressure changes when the device is placed in downhole drilling mud or other harsh environments. Most preferably, pressure compensation is effective to accommodate environmental pressures above 20,000 psi.

  It will be appreciated that a channel filled with a relatively incompressible fluid may not be effective in acoustically isolating the inner surface of the functional element from the interior of the inner housing. This is in contrast to a similarly structured device that includes a channel that is filled with gas and acoustically decouples the inner surface of the functional element from the interior of the inner housing.

  Referring now to the drawings, FIG. 1 illustrates one embodiment of a pressure compensated transducer assembly of the present invention, the assembly having a closed transducer end 4a and a side wall 4b and a first interior. It includes an inner housing 4 that defines a space 4c. The assembly also includes an outer housing 6 having an open transducer end 6a and a sidewall 6b that defines a second interior space. The functional element is provided in the first internal space. The functional element shown comprises a first ceramic layer 1, a second ceramic layer 2 and a backing 3. The ceramic layer and backing layer are preferably held against the inner housing together by mechanical compression. The PEEK face plate 17 is preferably adhered to the outside of the inner housing and cooperates with the inner housing end 4a, the first ceramic layer 1, the second ceramic layer 2, and the backing 3 to provide a sonic sounder. .

  The inner housing 4 and the outer housing 6 are provided such that the outer housing is separated from the inner housing. A channel 19 is provided in the space between the outer housing and the inner housing, the channel comprising a transducer end 19a opened to the environment 20 and a connecting end 19b opened to the first inner space 4c. Have

  The blocking member 10 such as an O-ring is provided in the channel 19 and can move in the channel 19. The position of the blocking member defines the connecting end channel portion 19b and the transducer end channel portion 19a. The blocking member is effective to prevent fluid flow from the connecting end channel portion to the transducer channel portion.

  A relatively incompressible fluid is provided in the first interior space and extends into the connecting end channel portion toward the blocking member. The fluid is preferably a natural or synthetic oil capable of functioning in a high pressure and high temperature environment. For some applications, high temperature silicone oil is preferred.

  A second O-ring 8 may be provided around the connection end assembly to seal the internal space 4c from the control electronics. The oil filled inner housing space must be a closed space for the pressure compensation mechanism to function properly. For this reason, it is necessary to prevent oil leakage from the internal space 4c to the control electronic device.

  The control electronics 5 enters the device via the connection end assembly. The control electronics drives and controls the piezo element and transmits an acoustic wave when the active device is in “transmit” mode and receives an acoustic wave when the device is in “receive” mode.

  FIG. 2 shows another embodiment of the pressure compensated transducer assembly of the present invention having the same functional elements recognized. The illustrated transducer assembly includes an inner housing 4 having a closed transducer end 4a and a side wall 4b defining a first interior space 4c. The outer housing 6 has an open transducer end 6a and a side wall 6b and defines a second internal space. The functional element is provided in the first internal space. The functional element shown is a piezoelectric transducer having a first ceramic layer 1, a second ceramic layer 2 and a backing 3. The piezoelectric transducer is positioned in the internal space 4c so that the surface of the piezo disc is held in close contact with the inner surface of the housing floor 4a. The PEEK faceplate 17 is bonded to the outer surface of the inner housing floor 4a and cooperates with the housing floor and the first ceramic layer 1, the second ceramic layer 2, and the backing 3 to provide a sonic sounder.

  A channel 19 is provided in the space between the outer housing and the inner housing, the channel being a transducer end 19a open to the environment 20 and a connection end open to the first inner space 4c. 19b. In a preferred embodiment, channel 19 is open to the environment at a location adjacent to the transducer assembly where acoustic waves are radiated by the transducer. If the transducer assembly includes a faceplate as shown, the channel 19 is opened to the environment at a location adjacent to the faceplate. The most preferred channel 19 is opened in the direction in which the acoustic wave is emitted by the transducer.

  The channel 19 is sized so that fluid from drilling mud or the like can flow from the environment adjacent to the transducer to the transducer end 19a of the channel 19. Thus, the internal pressure at the transducer end 19a of the channel 19 is at or very close to the pressure on the outer surface of the transducer assembly from which the acoustic waves are emitted.

  The blocking member 10 is provided in the channel 19 and is movable in the channel 19. The position of the blocking member defines the connecting end channel portion 19b and the transducer end channel portion 19a. The blocking member is effective to prevent fluid flow from the connecting end channel portion to the transducer channel portion.

  A relatively incompressible fluid is provided in the first interior space and extends toward the blocking member to the connecting end channel portion.

The control electronics 5 enters the device via the connection end.
In operation, as the environmental pressure outside the assembly increases (such as when the assembly descends into an oil field), the movable blocking member 10 moves within the channel 19 in response to the increased environmental pressure. When the environmental pressure increases, the blocking member 10 moves away from the transducer end 19a of the channel 19 toward the connection end 19b. As a result, the size / capacity of the connection end 19b of the channel 19 is reduced. As the volume of the space 19b decreases, the pressure applied by the liquid inside the device increases until the pressure in the device balances the pressure on the transducer surface.

  While the invention has been illustrated and described in detail in the drawings and foregoing description, such is considered by way of illustration and not as a limitation on the nature, only the preferred embodiments are shown and described, and are within the spirit of the invention. It is understood that protection is sought for all changes and changes.

In addition, it is understood that the elements described herein may be combined in combinations and subcombinations other than those described as preferred embodiments. Further, the apparatus of the present invention may include some or all combinations of the disclosed elements, or the apparatus of the present invention may be substantially comprised of some or all combinations of the disclosed elements.

Claims (9)

A pressure compensated transducer assembly having a transducer end portion and a connecting end portion, the assembly comprising:
An inner housing having a closed transducer end and side walls defining a first interior space;
An outer housing having an open transducer end and sidewalls and defining a second interior space;
A transducer at the transducer end of the first internal space;
An inter-housing space between the outer housing and the inner housing, the inter-housing space being open to an environment adjacent to the transducer end of the inner housing; and A connecting end portion open to the first interior space, the assembly further comprising:
A blocking member located in the space between the housings, the blocking member being effective for separating and defining a converter end portion of the space between the housings from a connection end portion of the space between the housings; Effective to prevent fluid flow from the fluid to the transducer end and vice versa, the assembly further comprising:
An internal liquid in the first internal space and extending to the connecting end portion of the inter-housing space;
The blocking member is between the pressure applied by the environment to the transducer end of the inter-housing space and the pressure applied by the internal liquid to the connecting end of the inter-housing space. A pressure-compensated transducer assembly that is movable within the space between the housings in response to a pressure differential.   The transducer comprises one or more piezoelectric ceramic elements and a backing disposed between the piezoelectric ceramic elements and the connection end of the housing, and is produced by the one or more piezoelectric ceramic elements. The assembly of claim 1, wherein an acoustic wave is propagated through the transducer end of the housing.   The assembly of claim 1, wherein the internal liquid is oil.   The assembly of claim 1, further comprising a faceplate adjacent and in contact with the outside of the transducer end of the inner housing.   The assembly of claim 1, wherein the connecting end portion filled with the liquid in the inter-housing space is not effective to acoustically isolate the inner surface of the piezoelectric transducer from the inside of the inner housing.   The assembly of claim 1, wherein the inner housings are substantially spaced within the outer housing such that the inter-housing space surrounds the inner housing.   The inter-housing space includes one or more channels between the inner housing and the outer housing, the channels being open to the environment at one end adjacent to the transducer end of the inner housing. The assembly of claim 1, wherein the other end is open to the first interior space. An acoustic transducer used in a high temperature and high pressure environment,
a) a housing having a transducer end face and defining a closed and oil-filled internal space;
b) a piezoelectric transducer assembly in an interior space filled with the oil;
c) a channel connecting the internal space filled with oil to the external environment around the transducer, the channel being open to the external environment with one end adjacent to the transducer end face. One end is opened to the internal space, and the acoustic transducer further comprises:
d) comprising a blocking element that is free to move within the channel and is effective to prevent fluid flow from the internal space through the channel to the external environment and vice versa;
As pressure builds up in the external environment, the blocking element moves through the channel until the difference in pressure between the internal space and the external environment is balanced.   The converter according to claim 8, wherein the blocking member is an O-ring.