GB2405933A - Measuring movement of a hydraulic actuator - Google Patents
Measuring movement of a hydraulic actuator Download PDFInfo
- Publication number
- GB2405933A GB2405933A GB0321445A GB0321445A GB2405933A GB 2405933 A GB2405933 A GB 2405933A GB 0321445 A GB0321445 A GB 0321445A GB 0321445 A GB0321445 A GB 0321445A GB 2405933 A GB2405933 A GB 2405933A
- Authority
- GB
- United Kingdom
- Prior art keywords
- rotary member
- piston
- rotation
- rotary
- actuator
- 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- Withdrawn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
-
- 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
- F15B15/2823—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT by a screw mechanism attached to the piston
-
- 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
- G01D5/42—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 fluid means
-
- 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
- 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
- G01D2205/00—Indexing scheme relating to details of means for transferring or converting the output of a sensing member
- G01D2205/10—Detecting linear movement
- G01D2205/14—Detecting linear movement by converting the linear movement into a rotary movement
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Actuator (AREA)
Abstract
A device for measuring linear movement of a hydraulically actuated piston 3 comprises a rotary member 13 coupled to the piston, such that linear movement of the piston causes rotation of the rotary member; and means for detecting and measuring rotation of the rotary member. The rotary member preferably comprises a threaded rod mounted to the base of the cylinder 2 by bearing means 17. The means for measuring rotation of the rotary member may include means of detecting sound generated as the rotary member rotates; means for detecting light reflected from a rotary member provided with alternating dark and light regions; means of detecting power generated by an electrical generator in response to rotary movement; or means for detecting light generated by an LED driven by the electrical generator. The device allows linear movement of the piston to be detected accurately.
Description
MEASURING MOVEMENT OF A HYDRAULIC ACTUATOR
The present invention relates to a hydraulic actuator, a method for measuring the linear position of a hydraulic actuator and to a device for measuring the linear position of a hydraulic actuator A known problem with hydraulic actuators is that it is difficult to conveniently and accurately determine the position of the parts being moved. In a typical hydraulic actuator, a cylinder in which a linearly moveable piston is mounted receives hydraulic fluid from a source comprising a pump, control electronics and control valves. The hydraulic fluid is passed between the fluid source and the hydraulic actuator by a pipeline, and the pressure of the hydraulic fluid brings about a linear motion of the piston. Methods of measuring the simple linear motion of the piston in response to hydraulic fluid being pumped into the cylinder employed in the prior art have been found not to be of sufficient accuracy for some applications.
According to a first aspect of the invention, there is provided a device for measuring linear movement of a hydraulically actuated piston, the device including a rotary member couplable to the piston such that linear movement of Be piston causes rotation of the rotary member, and means for detecting rotation ofthe rotary member.
According to a second aspect of the invention, there is provided a hydraulic actuator including a cylinder; a piston mounted for linear movement in the cylinder in response to hydraulic fluid pressure applied to the cylinder; a rotary member mounted in the cylinder and coupled to the piston such that linear movement of the piston causes rotation of the rotary member with respect to the cylinder; and means for measuring rotation of the rotary member and for generating an output signal indicative movement of the piston.
According to a furler aspect of the invention, there is provided a method of measuring movement of a hydraulically actuated, linearly moveable piston in a cylinder, including measuring rotation of a rotas member which is coupled to the piston such that the rotary member is caused to rotate by linear movement of the piston.
The rotary member may, for example, be coupled to the piston by means of co-operating helical screw threads provided on the rotary member and the piston. Conveniently, the rotary member comprises a rod which passes through an aperture on the base of the piston. The rod has an external screw thread and the hole in the base of the piston has an internal screw thread.
The rod may be rotatably mounted to the base of the cylinder by suitable bearing means.
In the embodiment the rotary member includes an indicator portion adapted to provide a measurable indication of rotation of the rotary member.
The rotation of the rotary member may be measured by any suitable means, examples of which are given below. It has been found that rotation of the rotary member can be measured more easily and/or with greater accuracy than simply directly measuring linear movement of the piston within the cylinder. The coupling of the piston to the rotary member can be geared, so that a small amount of linear movement to the piston results in a large angular movement of the rotary member. The larger the angular movement of the rotary member for a given amount of linear movement of the piston, the easier it is to measure accurately the linear movement of the piston (which will be proportional to the angular movement of the rotary member).
One way of converting the linear motion in the piston into rotary motion involves mounting the piston to a threaded rotary member which is rotatably mounted to the cylinder by a bearing at the head of the rotary member. The end of the piston in contact with the hydraulic fluid has a hole formed therein which has a screw thread corresponding to the thread of the rotary member. The threaded rotary member sealingly engages the hole, and the linear movement of the piston brought about by the hydraulic fluid pressure causes the threaded rotary member to rotate due to the nature of the cooperation between the screw threads. The linear motion of the piston is therefore transformed into rotary motion in the threaded rotary member. The problem of measuring linear motion is therefore converted into one of measuring rotary motion.
A solution to the problem of measuring the rotary motion of the threaded rotary member is to create serrations in the outer edge of the head of the threaded rotary member and affix a reed in a position where it contacts the serrated outer edge of the head. The rotation of the head can then be measured in terms of the noise created when the reed is hit by the serrations. This noise is conveyed along the hydraulic fluid to a sensor mounted in the hydraulic fluid supply reservoir, which converts the noise created when the reed is hit by the serrations into a reading for the position of the piston. In order to filter out extraneous noise created by the system, the sensor and reed could be frequency matched.
An alternative solution is to create alternating light and dark bands on the outer edge of the head of the threaded rotary member and affix an optical fibre in a position where it can sense the alternation of light and dark on the outer edge of the head. The rotation of the head can then be measured in terms of the modulation of light emanating from the distal end of the optical fibre. The light modulation is conveyed along the optical fibre to a sensor mounted in the hydraulic fluid supply reservoir, which converts the modulation of light into a reading for the position of the piston. The optical fibre could be carried in the hydraulic fluid to the sensor, or alternatively could be embedded in the wall of the hydraulic fluid pipe, thereby not requiring any external cabling in the system.
A further alternative solution is to incorporate a generator into the system, to be powered by the rotation of the threaded rotary member itself, thus creating a current reflecting the movement of the piston. This current could be carried to a sensor mounted in the hydraulic fluid supply reservoir either by wires carried in the hydraulic fluid or by wires embedded in the wall of the hydraulic fluid pipe. Alternatively the generated current could be used to power an LED mounted to the outer edge of the head of the threaded rotary member. An optical fibre could then be affixed in a position where it can sense the rotation of the head by monitoring the LED, with the signal conveyed along the optical fibre to a sensor mounted in the hydraulic fluid supply reservoir. The optical fibre could be carried in the hydraulic fluid to the sensor, or alternatively could be embedded in the wall of the hydraulic fluid pipe, thereby not requiring any external wiring in the system.
For a better understanding of the present invention, a hydraulic actuator, and a method and a device for measuring the linear position of a hydraulic actuator, embodying the invention, will now be described by way of example, with reference to the accompanying drawings in which: Figure 1 shows a cross-section through a hydraulic actuator comprising a piston sealingly engaged by a threaded rod for converting linear motion into rotary motion; Figure 2 shows a perspective view of a hydraulic actuator comprising a piston sealingly engaged by a threaded rod for converting linear motion into rotary motion; Figure 3 shows a cross-section through the hydraulic actuator of Figure 1, with the head of the threaded rod serrated on the outer edge and contacted by a reed for the measurement ofthe rotary motion ofthe head, Figure 4 shows a cross-section through the hydraulic actuator of Figure 1, with the head of the threaded rod comprising alternating light and dark bands on the outer edge, these light and dark bands being sensed by an optical fibre linked to a sensor; Figure 5 shows a cross-section of the hydraulic actuator of Figure 1, with the system incorporating a generator which supplies a current to a sensor via a wire when the threaded rod rotates; and Figure 6 shows a cross-section of the hydraulic actuator of Figure 1, with the system incorporating a generator which powers an LED mounted to the outer edge of the head of the threaded rod and an optical fibre linked to a sensor which senses the movement of the LED.
In the drawings, like elements are generally designated with the same reference numeral.
Figure 1 shows a cross-section of a hydraulic actuator 1 comprising a cylinder 2, in which a hydraulic ram 3 receives hydraulic fluid 5 from a fluid source 7. The fluid source 7 is capable of controlled supply of fluid under pressure, and comprises a pump, control electronics and control valves (not shown). The hydraulic fluid 5 is passed between the fluid source 7 and the piston 3 by a pipeline 9. Thus the hydraulic fluid 5 causes linear movement in the piston 3 by applying fluid pressure thereto.
The piston 3 may be moved forwards or backwards (arrow A) in the cylinder 2 by controlling the application of fluid from fluid source 7.
Thus far what has been described is conventional.
In the embodiments of the invention, the end of the cylinder 3 in contact with the hydraulic fluid 5 has a hole formed therein which has a helical screw thread 11. A helically threaded rod 13, the thread 15 of which cooperates with the thread 11 of the hole, is rotatably mounted to the cylinder 1 by a bearing 17 at the head 19 of the threaded rod 13. The threaded rod 13 sealingly engages the hole formed in the piston 3 so that hydraulic fluid cannot pass into the cylinder 3. Linear movement of the hydraulic piston 3, brought about by the pressure ofthe hydraulic fluid 5, causes the threaded rod 13 to rotate (arrow B) due to the nature of the cooperation between the screw threads 1 1 and 15.
Figure 2 shows a perspective view of a hydraulic actuator 1, showing how the threaded rod 13 sealingly engages the hole formed in the end of the piston 3. Linear motion in the hydraulic piston 3, created by the pressure ofthe hydraulic fluid 5, causes rotary motion in the threaded rod 13 and consequent the rotation ofthe head 19 ofthe threaded rod 13.
Thus, the arrangement shown in Figures 1 and 2 converts linear motion of the piston 3 in the direction of arrow A, as a result in variations of the fluid pressure from fluid source 7, into angular or rotational movement in the direction of arrow B of the rod 13 and its attached head 19. The amount of rotation (or angular displacement) of the rod 13 provided by a given amount of linear movement of the piston 3 can be set by selecting different thread patterns for the rod 13 and the piston 3. A thread pattern which causes a larger amount of rotation for a given amount of linear movement of the piston 3 may allow for a more precise measurement of the linear movement of the piston 3.
The rotation ofthe rod 13 can be measured in any suitable manner.
Figure 3 shows one solution to the problem of measuring the rotary motion of the threaded rod 13. A series of serrations 21 is formed in the outer edge of the head 19 of the threaded rod 13. A reed 23 is affixed in a position where it contacts the serrated outer edge of the head 19, and so the rotation of the head 19 can be measured by detecting the sound created when the reed 23 is hit by the moving serrations 21 of the head 19. The sound is conveyed by the hydraulic fluid 5 to a sensor 25 mounted in the hydraulic fluid supply reservoir 7. The sensor 25 detects the sound generated by the reed 23 hitting the serrations 21.
For example, the sensor 25 may be a pressure sensor, which detects pressure variations in the hydraulic fluid. As the reed 23 hits the serrations 21 a pressure variation in the hydraulic fluid is generated, which is carried by the pipeline 9 to the sensor 25. When the rod 13 is rotating at a regular angular rate, the pressure variations caused by reed 23 hitting the serrations 21 will produce a series of regular pressure peaks at the sensor 25. The distance between these pressure peaks will be indicative of the angular rate of rotation of the head 19. When the peaks are close together, this is indicative of a high angular rate. At any time, the distance between adjacent peaks detected by the sensor 25 will be indicative of the angular rate of rotation of the head 19.
It is likely that the hydraulic fluid in the region of sensor 35 will include pressure variations generated by sources other than the reed 23 striking the serrations 21. Software which processes the signals generated by sensor 25 can extract the relatively regular pattern of signals generated by the reed 23/serrations 21 from the less regular signals generated as a result of pressure variations caused by other sources. Advantageously, however, the reed 23 will be configured to generate sound of a predetermined frequency range. The sensor 25 or software processing signals of the sensor 25, can then be configured to be sensitive to only pressure variations having the predetermined frequency range, thereby substantially eliminating signals generated by extraneous pressure variations.
An alternative solution to the problem of measuring the rotary motion of the threaded rod 13 is shown in Figure 4. Alternating light and dark bands 27 are created on the outer edge of the head 19 of the threaded rod 13. A fibre optic cable 29 is affixed in a position where it can sense the alternation of light and dark on the outer edge of the head 19. The rotation of the head 19 can then be measured by detecting the modulation of light emanating from the distal end of the optical fibre 29. The light modulation is conveyed along the optical fibre 29 to a sensor 31 mounted in the hydraulic fluid supply reservoir 7, which converts the modulation of light into a reading for the position of the hydraulic actuator 3. The optical fibre 29 could be carried in the hydraulic fluid 5 to the sensor 31, or alternatively could be embedded in the wall of the hydraulic fluid pipe 9 (as shown), thereby not requiring any external cabling in the system.
This is advantageous because external cabling is prone to damage.
Figure 5 shows a further alternative solution to the problem of measuring the rotary motion of the Treaded rod 13, where a generator 33 is IS incorporated into the actuator 1. The generator 33 is powered by the rotation of the threaded rod 13, thus creating a current indicative of the movement of the hydraulic ram 3. The current is carried to a sensor 35 mounted in the hydraulic fluid supply reservoir 7 by a wire 37 which could be carried in the hydraulic fluid 5 to the sensor 35, or alternatively could be embedded in the wall of the hydraulic fluid pipe 9, thereby not requiring any external wiring in the system.
Figure 6 shows a different solution using the generator 33 introduced in Figure 5 wherein the generated current is used to power an LED 39 mounted to the outer surface of the head 19 of the threaded rod 13. A fibre optic cable 29 is affixed in a position where it can sense the rotation ofthe head 19 by monitoring light emitted by the LED 39, with the signal conveyed along the optic fibre cable 29 to a sensor 31 mounted in the hydraulic fluid supply reservoir 7. Again, the fibre optic cable 29 could be carried in the hydraulic fluid 5 to the sensor 31, or alternatively could be embedded in the wall of the hydraulic fluid pipe 9, thereby not requiring any external cabling in the system.
The Figure 4 and 6 embodiments show a fibre optic cable 29 which carries light to the sensor 31. As an alternative to the provision of a fibre optic cable the light from the markings 27 or any LED 39 may be carried along the pipeline 9 to the sensor 31, with the pipeline 9 acting as an optical pipe. For such an arrangement to operate effectively, it may be necessary for a direct line of sight to exist between the sensor 31 and the markings 27/LED 39. Alternatively, if a corner in the pipeline 9 is provided (as shown in the drawings) a mirror may be appropriately positioned at the corner to reflect the light so that it can successfully pass around the corner so that it reaches the sensor 31.
As a modification to the Figure 6 embodiment, the LED 39 is omitted.
The hydraulic fluid is modified so that it is electronically conductive.
The sensor 31 is replaced by a device for measuring electrical current.
The conductive hydraulic fluid completes an electrical circuit between the current sensor 31 and the generator 33. Current generated by the generator 33 flows through the conductive hydraulic fluid, and this current is measured by sensor 31. The current measurement is indicative ofthe rate of rotation ofthe rod 13.
Although in the embodiments show the sensors 25 and 31 are located in the fluid source 7, it may be possible to locate the sensor at the base of the hydraulic actuator 1 near the head 19 of the rod 13, or near the bearing 17 to which the head 19 is attached. This will reduce the problem of conveying optical or electrical signals to the sensor 25, 31.
However, the signals generated by the sensor 25, 31 are likely to be required at the fluid supply 7 in order to control that fluid supply (and consequently control movement of the piston 3 and the component to which it is attached - not shown - for controlling movement of that component). The signals generated by the sensor 25, 31 may be carried by an electrical cable embedded in the wall of the hydraulic actuator 1 and pipeline 9.
Other methods of creating rotary motion in response to the linear motion of the actuator could of course be used in this system, and various other methods for measuring the rotation of the threaded rod could also be employed. The examples given herein are not intended to limit the scope ofthe invention.
It should be understood that the designation of components numbered 2 and 3 as a "cylinder" and a "piston" respectively is not intended to, and is not, limitative of the shape of the components - these words are intended to indicate the function of the components. The cylinder and piston in the embodiment are circular in transverse cross-section. However, those components could be elliptical, rectangular or any other suitable shape.
Claims (24)
1. A device for measuring linear movement of a hydraulically actuated piston, the device including a rotary member couplable to the piston such that linear movement of the piston causes rotation of the rotary member, and means for detecting rotation of the rotary member.
2. A hydraulic actuator including a cylinder; a piston mounted for linear movement in the cylinder in response to hydraulic fluid pressure applied to the cylinder; a rotary member mounted in the cylinder and coupled to the piston such that linear movement of the piston causes rotation of the rotary member with respect to the cylinder; and means for measuring rotation of the rotary member and for generating an output signal indicative movement of the piston.
3. The device of claim 1 or actuator of claim 2, wherein the rotary member is coupled to the piston by means of co-operating helical threads provided on the rotary member and the piston.
4. The device or actuator of any one of the preceding claims, wherein the rotary member comprises a rod which passes through the base of the piston.
5. The device or actuator of claim 4 wherein the rod is rotatably mounted to the base of the cylinder by bearing means.
6. The device or actuator of any one of the preceding claims wherein the rotary member includes an indicator portion adapted to provide a measurable indication of rotation of the rotary member. s
7. The device or actuator of claim 6, wherein the indicator portion includes a plurality of indentations in the outer surface thereof, wherein a reed is fixed in a position where it contacts the indentations, and wherein means is provided for detecting the sound generated when the reed is hit by the indentations as the rosary member rotates.
8. The device or actuator of claim 6, wherein the indicator portion includes alternating light and dark regions on the outer surface thereof, and wherein means is provided for detecting variation in light reflected from the indicator portion as it rotates.
9. The detector or actuator of claim 6, including an electrical generator which generates power in response to the rotary movement of the rotary member, and means for measuring the power generated by the generator as the rotary member rotates.
10. The device or actuator of claim 6, including an electrical generator which generates power in response to a rotary movement of the rotary member, a light source mounted on the indicator portion of the rotary member which is powered by the generator, and means for detecting light at a fixed position with respect to the rotary member.
S
11. A method of measuring movement of a hydraulically actuated, linearly moveable piston in a cylinder, including measuring rotation of a rotary member which is coupled to the piston such that the rotary member is caused to rotate by linear movement of the piston.
12. The method of claim 11, wherein the rotary member is caused to rotate by linear movement of the piston by the co-operation of helical threads provided on the rotary member and the piston.
13. The method of claim 11 or 12, wherein the rotary member comprises a rod which passes through the base of the piston.
14. The method of claim 11, 1 2 or 1 3, wherein the rod is rotatably mounted to the base of the cylinder by bearing means.
15. The method of claim 11, 12, 13 or 14, including adapting an indicator portion of the rotary member so as to produce a measurable indication of rotation of the rotary member.
16. The method of claim 15, wherein the rotation of the rotary member is measured by creating a plurality of indentations in the outer surface of the indicator portion of the rotary member, affixing a reed in a position where it contacts the plurality of indentations, and detecting the sound generated when the reed is hit by the indentations as the rotary member rotates.
17. The method of claim 15, wherein the rotation of the rotary member is measured by creating alternating light and dark regions on the outer surface of the indicator portion of the rotary member, and detecting the variation in light reflected from the indicator portion as it rotates.
18. The method of claim 15, wherein the rotation of the rotary member is measured by providing an electrical generator which generates power in response to rotary movement of the rotary member and measuring the power generated by the generator as the rotary member rotates.
19. The method of claim 15, wherein the rotation of the rotary member is measured by using the generated power to drive a light source affixed to the indicator portion of the rotary member, and detecting light at a fixed position with respect of the rotary member.
20. A method for measuring the linear position of a hydraulic actuator, wherein linear motion of the hydraulic actuator is translated into rotary motion in an associated element and the rotary motion of the associated element is measured.
21. A method according to claim 20, wherein the rotary motion is translated in a threaded rod, and the linear motion of the hydraulic actuator is measured by monitoring the rotation of the threaded rod.
22. A method substantially as hereinbefore described with reference to and/ or substantially as illustrated in the accompanying drawings.
23. A device for measuring the movement of a hydraulically actuated piston substantially as hereinbefore described with reference to and/or substantially as illustrated in the accompanying drawings.
24. A hydraulic actuator substantially as hereinbefore described with reference to and/or substantially as illustrated in the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0321445A GB2405933A (en) | 2003-09-12 | 2003-09-12 | Measuring movement of a hydraulic actuator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0321445A GB2405933A (en) | 2003-09-12 | 2003-09-12 | Measuring movement of a hydraulic actuator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0321445D0 GB0321445D0 (en) | 2003-10-15 |
| GB2405933A true GB2405933A (en) | 2005-03-16 |
Family
ID=29227010
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0321445A Withdrawn GB2405933A (en) | 2003-09-12 | 2003-09-12 | Measuring movement of a hydraulic actuator |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2405933A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104807486A (en) * | 2015-02-06 | 2015-07-29 | 纳米新能源（唐山）有限责任公司 | Pneumatic sensor |
| CN105973281A (en) * | 2016-05-06 | 2016-09-28 | 东南大学 | Incremental linear rotation two-degree-freedom position detecting device |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109724936A (en) * | 2019-02-21 | 2019-05-07 | 福州普贝斯智能科技有限公司 | A kind of water quality spectroanalysis instrument |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB732465A (en) * | 1952-11-28 | 1955-06-22 | Generai Motors Corp | Improved power transmission mechanism |
| GB1253930A (en) * | 1968-12-30 | 1971-11-17 | Norsk Hydro Verksteder As | Position indicating of the movable member of a hydraulic system |
| GB2076469A (en) * | 1980-04-29 | 1981-12-02 | Secretary Industry Brit | Fluid actuated ram with position measuring device |
| WO1982004293A1 (en) * | 1981-05-28 | 1982-12-09 | Archer John Richard | Hydraulic linear actuator |
| GB2154282A (en) * | 1984-02-14 | 1985-09-04 | H C H Manufacturing Ltd | Fluid pressure actuators |
| WO1990008904A1 (en) * | 1989-01-26 | 1990-08-09 | Arcos Hydraulik Ab | Fluid-powered precision oscillator |
| US5192174A (en) * | 1989-05-07 | 1993-03-09 | Hans Hartmann | Hydraulic drive for a tool head |
-
2003
- 2003-09-12 GB GB0321445A patent/GB2405933A/en not_active Withdrawn
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB732465A (en) * | 1952-11-28 | 1955-06-22 | Generai Motors Corp | Improved power transmission mechanism |
| GB1253930A (en) * | 1968-12-30 | 1971-11-17 | Norsk Hydro Verksteder As | Position indicating of the movable member of a hydraulic system |
| GB2076469A (en) * | 1980-04-29 | 1981-12-02 | Secretary Industry Brit | Fluid actuated ram with position measuring device |
| WO1982004293A1 (en) * | 1981-05-28 | 1982-12-09 | Archer John Richard | Hydraulic linear actuator |
| GB2154282A (en) * | 1984-02-14 | 1985-09-04 | H C H Manufacturing Ltd | Fluid pressure actuators |
| WO1990008904A1 (en) * | 1989-01-26 | 1990-08-09 | Arcos Hydraulik Ab | Fluid-powered precision oscillator |
| US5192174A (en) * | 1989-05-07 | 1993-03-09 | Hans Hartmann | Hydraulic drive for a tool head |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104807486A (en) * | 2015-02-06 | 2015-07-29 | 纳米新能源（唐山）有限责任公司 | Pneumatic sensor |
| CN105973281A (en) * | 2016-05-06 | 2016-09-28 | 东南大学 | Incremental linear rotation two-degree-freedom position detecting device |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0321445D0 (en) | 2003-10-15 |
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| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |