GB2043250A - Ultrasonic transducer arrangement for indicating position of a piston - Google Patents
Ultrasonic transducer arrangement for indicating position of a piston Download PDFInfo
- Publication number
- GB2043250A GB2043250A GB8004996A GB8004996A GB2043250A GB 2043250 A GB2043250 A GB 2043250A GB 8004996 A GB8004996 A GB 8004996A GB 8004996 A GB8004996 A GB 8004996A GB 2043250 A GB2043250 A GB 2043250A
- Authority
- GB
- United Kingdom
- Prior art keywords
- receiver
- cylinder
- ultrasonic
- transmitter
- piston
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S11/00—Systems for determining distance or velocity not using reflection or reradiation
- G01S11/14—Systems for determining distance or velocity not using reflection or reradiation using ultrasonic, sonic, or infrasonic waves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
- F15B15/20—Other details, e.g. assembly with regulating devices
- F15B15/28—Means for indicating the position, e.g. end of stroke
- F15B15/2815—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT
- F15B15/2884—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT using sound, e.g. ultrasound
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B17/00—Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/48—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using wave or particle radiation means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
- G01S15/88—Sonar systems specially adapted for specific applications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
- G01S7/52004—Means for monitoring or calibrating
- G01S7/52006—Means for monitoring or calibrating with provision for compensating the effects of temperature
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
- G01S7/52004—Means for monitoring or calibrating
- G01S2007/52014—Means for monitoring or calibrating involving a reference reflector integrated in the sensor or transducer configuration
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
- G01S7/52004—Means for monitoring or calibrating
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Acoustics & Sound (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Length Measuring Devices Characterised By Use Of Acoustic Means (AREA)
Abstract
The position of a piston (4, 4A) in a cylinder (1) containing hydraulic oil is indicated by an ultrasonic transmitter (8) and an ultrasonic receiver (9) located to provides path for ultrasonic radiation substantially parallel to the direction of relative linear movement between the piston and cylinder. Further ultrasonic means e.g. receiver (10), Figure 1 or transmitter (15) and receiver (16), Figure 2, provide a second path at least part of which is of constant length through the liquid in the cylinder, for compensating for changes in bulk- modulus and density of the hydraulic oil. <IMAGE>
Description
SPECIFICATION
Ultrasonic transducer
This invention relates to a transducer employing ultrasonic radiation for indicating linear displacement between two relatively movable members.
According to the present invention an ultrasonic transducer comprises a cylinder containing a quantity of liquid, a piston in the cylinder, the piston and cylinder being arranged for linear relative movement therebetween, an ultrasonic transmitter and an ultrasonic receiver located within the cylinder and arranged to provide a first path between them for ultrasonic radiation through the liquid in the cylinder and substantially parallel to the direction of relative movement of the piston and cylinder and ultrasonic means providing a second path for ultrasonic radiation through the liquid in the cylinder, at least part of the second path being of constant length.
In use, one or other of the piston and cylinder is fixed and the other is displaceable linearly with respect thereto. The ultrasonic radiation passing from the transmitter to the receiver extends substantially parallel to the direction of relative movement between the piston and the cylinder and the time elapsed from transmitting a signal to receiving it represents the separation of the transmitter and receiver. If the transmitter and receiver are mounted one on the piston and the other on the cylinder, the time delay between the output of the receiver from that of the transmitter indicates the separation of the parts of the piston and cylinder carrying the transmitter and receiver in the direction of relative movement therebetween.
Alternatively the receiver and transmitter may both be mounted on one or other of the piston or cylinderwith reflecting means mounted on the part on which the receiver and transmitter are not mounted. If the receiver and and transmitter are mounted equidistant from the reflecting means, then the time delay between the output of the receiver and that of the transmitter represents twice the separation of the receiver and transmitter from the reflecting means.
The output of the receiver does vary with changes in bulk-modulus and density of the liquid in the cylinder and consequently errors in the detected distance between the piston and cylinder can occur.
In order to compensate for this, said ultrasonic means are used to pass ultrasonic radiation along a second path through the liquid, the second path or part thereof being of constant length. Any changes in the bulk modulus and density of the liquid which affect the output of the receiver receiving ultrasonic radiation along the first path will simultaneously affect the output of a receiver receiving ultrasonic radiation along the second path and since at least part of the second path is of constant length these errors which occur can be used to compensate for the errors resulting in the measurement of the length of the first path.
In one embodiment of the invention a single ultrasonic transmitter and two ultrasonic receivers are employed. The two receivers are fixed a constant distance apart in the direction of relative movement between the piston and cylinder and consequently as both receivers receive signals from the same transmitter the time difference in the electrical output from the two receivers is representative of the constant distance between the two receivers.
In an alternative embodiment ultrasonic radiation is passed along the first path from a transmitter to a receiver and a second transmitter and receiver are mounted a fixed distance apart within the cylinder so that the output from the second receiver represents a path of a constant distance through the liquid in the cylinder.
In order that the invention may be more readily understood it will now be described, by way of example only, with reference to the accompanying drawings, in which:
Figures 1, 2 and 3 are diagrammatic sectional side elevations of transducers in accordance with alternative embodiments of the invention, and
Figure 4 is a block diagram of the circuitry associated with the transducer of Figure 1.
Referring to Figure 1, an ultrasonic transducer comprises a cylinder 1 closed at its lower end by its end wall 2 and having an inlet 3 through which hydraulic oil can be transferred into and out of the interior of the cylinder. A piston 4 is displaceable in the cylinder and a sealing ring 5 serves to prevent flow of oil past the piston. The space between the piston and the end wall 2 of the cylinder is filled with hydraulic oil.
The face of the piston which is adjacent the end wall 2 of the cylinder has a recessed central portion 6 and a further recessed portion 7 leading inwardly from the central portion 6. An ultrasonic transmitter 8 is mounted on a plug 8' fitted in the end wall 2 of the cylinder substantially on the longitudinal axis of the piston and cylinder. A first ultrasonic receiver 9 is mounted on the base wall of the recess 6 and a second receiver 10 is mounted on the base wall of the recess 7. These two receivers are separated by a constant distanced1.
In use, ultrasonic radiation transmitted by the transmitter 8 is received by both of the receivers 9 and 10. The electrical output from the receiver 9 is representative of the distance d2 between the transmitter 8 and the receiver 9. The electrical output of the receiver 10 represents the distance between the transmitter 8 and the receiver 10 and this is equal to d1 + d2. If there are any errors in the difference in output of the receivers due to bulk modulus and density or other factors involving the acoustic composition of the hydraulic oil contained in the cylinder, then the errors affect the output from both receivers and since the distance between the two receivers is constant, then the errors can be compensated for.
Referring now to Figure 2, the piston 4A displaceable in the cylinder 1 has a central recess 12 in its end face and a further recess 13 offset from the axis of the piston. A first transmitter 8 is located on a plug 8' fitted into the end wall 2 of the cylinder and a first receiver 14 is mounted on the base wall of the recess 12. The transmitter 8 and the receiver 14 are in alignment and the path between them is parallel to the direction of movement of the piston in the cylinder. On opposite side walls of the recess 13 there are located as second ultrasonic transmitter 15 and a second ultrasonic receiver 16. These are separated by a constant distance.In use, the electrical output of the receiver 14 represents the position of the piston relative to the end wall 2 of the cylinder and the electrical output of the receiver 16 is electrically modified to be constant since it is a fixed distance away from the transmitter 15. These same electrical modifications simultaneously modulate the output of receiver 14 to compensate for varia- tions in the bulk-modulus, density or other factors affecting the acoustic composition of the hydraulic oil in the cylinder.
In all embodiments of the invention it is necessary that there should be no large bubbles of gas in the paths between the transmitters and the receivers and consequently in the embodiment shown in
Figure 1 a passage 20 leads to a gas collection duct 21 formed in the piston. If any bubbles are present in the hydraulic oil then they move upwardly through the passage 20 and collect in the duct 21. Similarly in the arrangement shown in Figure 2 the recesses 12 and 13 each have a passage 22 leading upwardly therefrom and the two passages are in communication with a gas collecting duct 23 formed in the piston.
Referring to Figure 3, the piston 4B displaceable in the cylinder 1 has a recess 13 in its end face offset from the axis of the piston. A first ultrasonic receiver 8 and a first ultrasonic receiver 24 are mounted side-by-side on a plug 8' fitted into the end wall 2 of the cylinder. A reflector 25 is mounted on the piston 1, or may form part of the piston, and is in alignment with the transmitter 8 and receiver 24. On the opposite side walls of the recess 13 there are located a second ultrasonic transmitter 15 and a second ultrasonic receiver 16. These are separated by a constant distance.
In use, the ultrasonic radiation from transmitter 8 passes through the oil in the cylinder and is reflected from the reflecting means 25 back to the first receiver 24. The output from the receiver 24 thus represents twice the distance between the transmitter 8 and the reflecting means 25.
In all embodiments of the invention the ultrasonic transmitters conveniently employ crystals of the
Piezoelectric type having a natural frequency of typically 2MHz.
Referring to Figure 4, which is a block diagram of the electrical circuitry associated with the transducer illustrated in Figure 1, reference numeral 30 represents the electronic apparatus associated with the transmitter 8 and reference numerals 31 and 32 represent electronic timers associated with receivers 9 and 10 respectively. The output from the transmitter electronic apparatus 30 is applied to both timers.
The electrical outputs from the transmitter electronics 30 and the timers 31 and 32 pass through respective separate modulators 34, 35 and 36. The output signals from the modulators 35 and 36 are applied to an integrator 37 to which a reference signal equivalent to the constant distanced1 is also applied. The difference between the output signals from the two timers associated with the receivers is compared with the reference signal in the integrator 37 and if there is any difference this difference is used to produce a correction signal which is applied to the modulators 35 and 36. This correction signal compensates for density and bulk-modulus changes in the hydraulic oil. The output signal from the modulator 35 represents the distance d2.
When electrical signals are applied to the transmitters electronic clocks are started as the ultrasonic radiation is transmitted into the hydraulic oil. After travelling their respective paths through the oil the piezoelectric receivers are activated and stop their respective clocks. The resulting time lapses are used to produce signals representative of the physical separations between the transmitters and the receivers.
The difference in the outputs from the receivers receiving radiation tends to deviate and this deviation is used to modify the gain of both signal processors 35 and 36 operating on the signals from the receivers and in the sense to reduce the deviation to zero. This means that the calibration of the transducer is maintained constant despite any acoustic changes in the hydraulic oil.
The transducers described above have particular application in rolling mills where they are located between the chocks supporting one of the rolls of the mill and a fixed part of the mill housing so that the separation between the chocks and the mill housing can be adjusted by changing the quantity of the oil in the cylinder and at the same time the transducer indicates accurately the distance between the chocks and the fixed part of the mill housing.
Another aspect of the invention is compensation for attenuation of the acoustic signal in the hydraulic oil. It is desirable to have constant amplitude ultrasonic pulses arriving at receiver9 or 14 there fore, as the distance d2 increases, the amplitude of the transmitted pulses from transmitter 8 is increased. The signal representative of distance d2 is applied to modulator 34 to modulate the transmitter power from transmitter 8.
Claims (11)
1. An ultrasonic transducer comprising a cylinder containing a quantity of liquid, a piston in the cylinder, the piston and cylinder being arranged for relative linear movementtherebetween, an ultraso nictransmitter and an ultrasonic receiver located within the cylinder and arranged to provide a first path between them for ultrasonic radiation through the liquid in the cylinder and substantially parallel to the direction of relative movement of the piston and cylinder, and
ultrasonic means providing a second path for ultrasonic radiation through the liquid in the cylinder, at least part of the second path being of constant length.
2. An ultrasonic transducer as claimed in claim 1, in which the transmitter is located on an end wall of the cylinder and the receiver is mounted on the piston.
3. An ultrasonic transducer as claimed in claim 2, in which said ultrasonic means comprises a second ultrasonic receiver mounted on the piston and arranged to receive radiation from the transmitter, said second receiver being located a constant distance from the first-mentioned receiver in the direction of said first path.
4. An ultrasonic transducer as claimed in claim 1, in which said ultrasonic means comprises a second ultrasonic receiver and a second ultrasonic transmitter spaced apart by a constant distance.
5. An ultrasonic transducer as claimed in claim 4, in which the second receiver and the second transmitter are mounted on the piston.
6. An ultrasonic transducer as claimed in claim 1, 4 or 5, in which the transmitter and receiver are positioned on one of the piston and cylinder and reflecting means is positioned on the other of the piston and cylinder, the reflecting means being positioned such that radiation from the transmitter is reflected back to the receiver.
7. An ultrasonic transducer as claimed in claim 6, in which the receiver and transmitter are mounted side-by-side on a plug fitted into an opening in an end wall of the cylinder.
8. An ultrasonic transducer as claimed in any preceding claim, in which means are provided for permitting bubbles in the liquid to escape from said first and second paths.
9. An ultrasonic transducer as claimed in any preceding claim, including means for comparing a signal representative of the measured length of the second path or the measured length of the part of the second path which is of constant length with a signal respresenting the actual value of said known length and for producing a signal representative of any error therebetween, said error signal, when produced, serving to modify the signals representative of the length of the first and second paths in the sense to reduce said error signal to zero.
10. An ultrasonic transducer as claimed in any preceding claim, including means for amplitude modulating the signal from the transmitter such that amplitude of the signal received at the receiver is independent of the separation of the transmitter and receiver.
11. An ultrasonic transducer substantially as hereinbefore described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8004996A GB2043250A (en) | 1979-02-23 | 1980-02-14 | Ultrasonic transducer arrangement for indicating position of a piston |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7906463 | 1979-02-23 | ||
| GB8004996A GB2043250A (en) | 1979-02-23 | 1980-02-14 | Ultrasonic transducer arrangement for indicating position of a piston |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2043250A true GB2043250A (en) | 1980-10-01 |
Family
ID=26270673
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8004996A Withdrawn GB2043250A (en) | 1979-02-23 | 1980-02-14 | Ultrasonic transducer arrangement for indicating position of a piston |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2043250A (en) |
Cited By (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0055120A1 (en) * | 1980-12-22 | 1982-06-30 | Froude Consine Limited | Improvements in or relating to methods of and apparatuses for indicating a predetermined position of a piston or crankshaft of a piston engine |
| EP0056905A1 (en) * | 1981-01-22 | 1982-08-04 | Froude Consine Limited | Method of and apparatus for detecting a piston ring in a piston engine |
| FR2512550A1 (en) * | 1981-09-04 | 1983-03-11 | Shelomentsev Timofei | METHOD FOR CONTROLLING THE OPERATION OF THE MECHANISMS OF AN INTERNAL COMBUSTION ENGINE AND DEVICE FOR CARRYING OUT SAID METHOD |
| US4444049A (en) * | 1980-12-22 | 1984-04-24 | Froude Consine Limited | Engine testing apparatus and methods |
| EP0146829A2 (en) * | 1983-12-07 | 1985-07-03 | Asea Ab | Ultrasonic measuring device |
| FR2573200A1 (en) * | 1984-11-15 | 1986-05-16 | Siette Spa | SYSTEM FOR MEASURING THE HEIGHT ABOVE THE GROUND OF A VEHICLE |
| GB2172995A (en) * | 1985-03-30 | 1986-10-01 | Emhart Ind | Monitoring the position of a member |
| DE3608384A1 (en) * | 1986-03-13 | 1987-09-17 | F & O Electronic Systems | Method for measuring displacements, in particular for the absolute measurement of short displacements, via the propagation time of pulses in a material support medium, and associated device for carrying out the method |
| FR2607930A1 (en) * | 1986-12-03 | 1988-06-10 | Vasselet Regis | Machine for unidirectional plastic flow mechanical test at constant stress for soft tissue samples |
| DE3815002A1 (en) * | 1988-05-03 | 1989-11-16 | Krupp Polysius Ag | GOOD BED ROLL MILL |
| DE3820883A1 (en) * | 1988-06-21 | 1989-12-28 | Hoelter Heinz | Apparatus and device for determining the piston stroke in hydraulic cylinders, with the aid of ultrasound |
| DE3833145A1 (en) * | 1988-09-29 | 1990-04-05 | Siemens Ag | Floating-body flow meter with ultrasonic position measurement |
| DE4236057A1 (en) * | 1992-10-26 | 1994-04-28 | Tox Pressotechnik Gmbh | Distance sensor for press. converter - has immersion piston, pneumatic controller, working piston displacement detector and electronic controller |
| EP1139117A1 (en) * | 2000-03-14 | 2001-10-04 | Kabushiki Kaisha Toyoda Jidoshokki Seisakusho | Device and method for detecting position of movable body by using ultrasonic waves |
| US6698289B1 (en) | 1998-12-21 | 2004-03-02 | Trw Automotive Electronics & Components Gmbh & Co. Kg | Device for measuring distance |
| WO2005003571A1 (en) * | 2003-07-04 | 2005-01-13 | Horst Siedle Gmbh & Co. Kg | Method for determining a current position of a piston movably accommodated in a cylinder |
| EP1923716A1 (en) * | 2006-11-20 | 2008-05-21 | Robert Bosch Gmbh | Distance measuring method and distance measuring device |
| FR2938926A1 (en) * | 2008-11-26 | 2010-05-28 | Mcb Ind | Transmitter and receiver distance measurement method for measuring fork height of lifting truck, has determining current speed of actual sound, and estimating distance between transmitter and receiver from current speed of actual sound |
-
1980
- 1980-02-14 GB GB8004996A patent/GB2043250A/en not_active Withdrawn
Cited By (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0055120A1 (en) * | 1980-12-22 | 1982-06-30 | Froude Consine Limited | Improvements in or relating to methods of and apparatuses for indicating a predetermined position of a piston or crankshaft of a piston engine |
| US4444049A (en) * | 1980-12-22 | 1984-04-24 | Froude Consine Limited | Engine testing apparatus and methods |
| US4520660A (en) * | 1980-12-22 | 1985-06-04 | Froude Consine Limited | Engine testing apparatus and methods |
| EP0056905A1 (en) * | 1981-01-22 | 1982-08-04 | Froude Consine Limited | Method of and apparatus for detecting a piston ring in a piston engine |
| FR2512550A1 (en) * | 1981-09-04 | 1983-03-11 | Shelomentsev Timofei | METHOD FOR CONTROLLING THE OPERATION OF THE MECHANISMS OF AN INTERNAL COMBUSTION ENGINE AND DEVICE FOR CARRYING OUT SAID METHOD |
| EP0146829A2 (en) * | 1983-12-07 | 1985-07-03 | Asea Ab | Ultrasonic measuring device |
| EP0146829A3 (en) * | 1983-12-07 | 1987-04-22 | Asea Ab | Ultrasonic measuring device |
| FR2573200A1 (en) * | 1984-11-15 | 1986-05-16 | Siette Spa | SYSTEM FOR MEASURING THE HEIGHT ABOVE THE GROUND OF A VEHICLE |
| GB2172995A (en) * | 1985-03-30 | 1986-10-01 | Emhart Ind | Monitoring the position of a member |
| DE3608384A1 (en) * | 1986-03-13 | 1987-09-17 | F & O Electronic Systems | Method for measuring displacements, in particular for the absolute measurement of short displacements, via the propagation time of pulses in a material support medium, and associated device for carrying out the method |
| FR2607930A1 (en) * | 1986-12-03 | 1988-06-10 | Vasselet Regis | Machine for unidirectional plastic flow mechanical test at constant stress for soft tissue samples |
| DE3815002A1 (en) * | 1988-05-03 | 1989-11-16 | Krupp Polysius Ag | GOOD BED ROLL MILL |
| DE3820883A1 (en) * | 1988-06-21 | 1989-12-28 | Hoelter Heinz | Apparatus and device for determining the piston stroke in hydraulic cylinders, with the aid of ultrasound |
| DE3833145A1 (en) * | 1988-09-29 | 1990-04-05 | Siemens Ag | Floating-body flow meter with ultrasonic position measurement |
| DE4236057A1 (en) * | 1992-10-26 | 1994-04-28 | Tox Pressotechnik Gmbh | Distance sensor for press. converter - has immersion piston, pneumatic controller, working piston displacement detector and electronic controller |
| US6698289B1 (en) | 1998-12-21 | 2004-03-02 | Trw Automotive Electronics & Components Gmbh & Co. Kg | Device for measuring distance |
| EP1139117A1 (en) * | 2000-03-14 | 2001-10-04 | Kabushiki Kaisha Toyoda Jidoshokki Seisakusho | Device and method for detecting position of movable body by using ultrasonic waves |
| US6490227B2 (en) | 2000-03-14 | 2002-12-03 | Kabushiki Kaisha Toyoda Jidoshokki Seisakusho | Device and method for detecting position of movable body by using ultrasonic waves |
| WO2005003571A1 (en) * | 2003-07-04 | 2005-01-13 | Horst Siedle Gmbh & Co. Kg | Method for determining a current position of a piston movably accommodated in a cylinder |
| EP1923716A1 (en) * | 2006-11-20 | 2008-05-21 | Robert Bosch Gmbh | Distance measuring method and distance measuring device |
| FR2938926A1 (en) * | 2008-11-26 | 2010-05-28 | Mcb Ind | Transmitter and receiver distance measurement method for measuring fork height of lifting truck, has determining current speed of actual sound, and estimating distance between transmitter and receiver from current speed of actual sound |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |