Gas content testing device for pressure-maintaining coring site

Abstract

The invention discloses a pressure-maintaining coring site gas content testing device, which comprises a pressure-maintaining outer cylinder, a spacing cylinder, a spacing plate, a sealing slip ring, an adjusting mechanism, a plugging mechanism and a push plate, and is characterized in that the spacing cylinder is fixedly arranged in the pressure-maintaining outer cylinder, and the push plate is slidably arranged in the spacing cylinder under the driving of a hydraulic rod; the push plate divides the interior of the spacing cylinder into two parts, a coring cavity is formed in the lower portion of the spacing cylinder, a spacing plate is fixedly arranged on the pressure maintaining outer cylinder, the spacing plate divides an annular space formed by the pressure maintaining outer cylinder and the spacing cylinder into two parts, and a measuring cavity is formed in the upper portion of the pressure maintaining outer cylinder. A measuring cavity is formed in the outer side of the pressure maintaining outer cylinder, a sealing sliding ring is arranged in the measuring cavity in a sealing and sliding mode, an adjusting mechanism is further arranged in the measuring cavity in a sliding mode, the sealing sliding ring can push the adjusting mechanism to slide, a blocking mechanism is fixedly arranged at the bottom of the pressure maintaining outer cylinder, and a plurality of supporting lugs are fixedly arranged on the outer side of the coring cavity in a circumferential mode.

Description

Technical Field

[0001] The invention relates to the technical field of shale gas exploration and development, and in particular to a pressure-maintaining coring on-site gas content testing device. Background Art

[0002] In the process of shale gas exploration and development, accurate measurement of shale gas content is an important basis for evaluating reservoir potential and formulating development plans. Traditional shale gas content testing generally uses a pressure-maintaining coring device to obtain core samples, and then desorbs the core samples to measure the gas content of the core, thereby calculating the gas content of the entire shale layer. Among them, the gas content of the core is composed of three parts, namely the desorbed gas content, the lost gas content, and the residual gas content. The calculation of the desorbed gas content and the residual gas content is relatively simple, while the test of the lost gas content is more difficult.

[0003] At present, the loss gas content is usually calculated through USBM (U.S. Bureau of Mines direct method) linear regression. This method is mainly based on diffusion simulation. In the early stage of desorption, the total amount of desorbed gas changes linearly with the square root of time. The loss gas content is directly calculated using linear fitting. However, in the actual coring process, the amount of gas desorption in the core will change due to changes in the core environment, which will cause an error between the calculated value and the actual value, and the accurate gas content cannot be measured. In addition, two sections of venting pipelines can be placed on the pressure-maintaining coring barrel, the venting pipelines can be connected to a water tank, and a metering cylinder can be set in the water tank to measure the amount of gas released in the pressure-maintaining barrel. Although this method can effectively measure the loss gas content, it is easily affected by the coring depth and has a small scope of application.

[0004] Therefore, it is necessary to provide a pressure-maintaining coring on-site gas content testing device to solve the problems raised in the above background technology. Summary of the invention

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a pressure-maintaining coring on-site gas content testing device, comprising a pressure-maintaining outer cylinder, a spacer cylinder, a spacer plate, a sealing slip ring, an adjusting mechanism, a plugging mechanism and a push plate, wherein a spacer cylinder is fixedly arranged in the pressure-maintaining outer cylinder, a push plate is slidingly arranged in the spacer cylinder driven by a hydraulic rod, the push plate divides the interior of the spacer cylinder into two parts and forms a coring cavity at the lower part of the spacer cylinder, a spacer plate is fixedly arranged on the pressure-maintaining outer cylinder, the spacer plate divides the annular space formed by the pressure-maintaining outer cylinder and the spacer cylinder into two parts and forms a measuring cavity at the upper part of the pressure-maintaining outer cylinder, a scale line is arranged at one end of the pressure-maintaining outer cylinder located in the measuring cavity, a sealing slip ring is sealingly and slidingly arranged in the measuring cavity, a distance sensor is embedded in the sealing slip ring, an adjusting mechanism is also slidingly arranged in the measuring cavity, and the sealing slip ring can push the adjusting mechanism to slide, a plugging mechanism is fixedly arranged at the bottom of the pressure-maintaining outer cylinder, and a plurality of supporting ears are fixedly arranged in a circle on the outer side of the coring cavity.

[0006] Further, as a preference, the adjustment mechanism comprises a slide rod, a connecting ring, an adjustment plate 1 and an adjustment plate 2, wherein the connecting rings are allocated with two, and a plurality of adjustment plates 1 and adjustment plates 2 are respectively fixedly arranged in a circumference on the two connecting rings, and the two connecting rings are fixedly connected by a plurality of slide rods;

[0007] The spacing cylinder is circumferentially provided with a plurality of sliding grooves for the sliding rod to seal and slide.

[0008] Further, as a preference, a plurality of sealing grooves 1 are circumferentially formed on one side of the partition plate close to the measuring cavity, and the adjustment plate 1 slides sealingly along the sealing grooves 1;

[0009] A plurality of sealing grooves 2 are circumferentially formed on one side of the pressure-maintaining outer cylinder close to the measuring chamber, and the regulating plate 2 slides sealingly along the sealing grooves 2.

[0010] Further, as a preference, the measuring cavity is provided with a plurality of air outlets and air inlet holes in a circumferential manner at the upper and lower ends thereof;

[0011] The regulating plate 1 is provided with an L-shaped air inlet 1 and an air outlet 1 which are staggered and can be connected to the air outlet and the air inlet at the lower end of the measuring cavity respectively;

[0012] The second regulating plate is provided with an L-shaped air inlet and an air outlet. The air inlet and the air outlet can be connected to the air outlet and the air inlet at the upper end of the measuring cavity respectively.

[0013] Further, as a preference, a plurality of through holes are provided on the coring cavity;

[0014] The spacer cylinder is provided with a plurality of air passages, and the air passages are communicated with the plurality of through holes and the air inlet holes.

[0015] Further, as a preference, the blocking mechanism comprises a blocking seat, a sealing plate and a driving plate, wherein the blocking seat is fixedly arranged at the bottom of the pressure-maintaining outer cylinder, a sealing rotation groove is provided on the blocking seat, six sealing plates are arranged in a circular sealing rotation in the sealing rotation groove, and a driving plate is arranged in a circular rotation in the sealing rotation groove;

[0016] A guide rod is fixedly arranged on the sealing plate, and six driving grooves are circumferentially provided on the driving plate, and the guide rod slides along the driving grooves.

[0017] Further, as a preference, the sealing plate is a triangular arc-shaped plate, an arc-shaped rotating block is fixedly arranged at the bottom of the sealing plate, and the circular shape of the arc-shaped rotating block is located on a vertical side of the sealing plate, and the two arc-shaped sides of the sealing plate close to the inner side of the coring cavity are respectively provided with upward and downward inclined push surfaces;

[0018] The sealing rotating groove is circumferentially provided with six arc-shaped rotating grooves, and the arc-shaped rotating block rotates along the arc-shaped rotating grooves.

[0019] Further, as a preference, an arc groove is provided on the sealing rotating groove, and an annular hydraulic cavity is provided on the arc groove;

[0020] An arc block is fixedly arranged on the driving plate, an annular hydraulic rod is fixedly arranged on the arc block, the arc block slides along the arc groove, and the annular hydraulic rod slides along the annular hydraulic cavity in a sealed manner.

[0021] Compared with the prior art, the present invention provides a pressure-maintaining coring on-site gas content testing device, which has the following beneficial effects:

[0022] In the present invention, by setting up the measuring chamber, the adjusting mechanism and the sealing slip ring, the free gas content of the core before being transported to the desorption tank can be accurately measured, thereby making the value of the total gas content of the core finally tested more accurate, and the pressure-maintaining outer cylinder can be transported to any depth for coring, and the lost gas content of any core can be accurately measured, thereby making the application range of the pressure-maintaining outer cylinder and the device as a whole wider and the measured gas content data more accurate. In addition, by setting up the sealing mechanism, the coring chamber can be effectively sealed, and the two arc-shaped edges of the sealing plate are respectively set with upward and downward inclined surfaces, so that the two adjacent sealing plates can use the upward and downward inclined surfaces to cut the core, and push the cut core, so that the core can be taken out as it is and can effectively avoid the core from being stuck on the sealing plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2 It is a schematic cross-sectional view of the overall structure of the present invention;

[0025] Figure 3 for Figure 1 A schematic diagram of the enlarged structure of the middle part A;

[0026] Figure 4 for Figure 1 A magnified schematic diagram of the structure of the middle B section;

[0027] Figure 5 for Figure 1 A magnified schematic diagram of the structure of the middle C section;

[0028] Figure 6 It is a structural schematic diagram of the adjustment mechanism in the present invention;

[0029] Figure 7 It is a structural schematic diagram of the blocking mechanism in the present invention;

[0030] In the figure: 1, pressure-maintaining outer cylinder; 11, measuring cavity; 111, air outlet; 112, air inlet; 12, sealing groove 2; 2, spacing cylinder; 21, coring cavity; 211, through hole; 22, supporting ear; 23, slide groove; 24, air passage; 3, spacing plate; 31, sealing groove 1; 4, sealing slip ring; 5, adjustment mechanism; 51, slide rod; 52, connecting ring; 53, adjustment plate 1; 53 1. Air inlet one; 532. Air outlet one; 54. Adjustment plate two; 541. Air inlet two; 542. Air outlet two; 6. Sealing mechanism; 61. Sealing seat; 611. Sealing rotating groove; 612. Arc groove; 62. Sealing plate; 621. Guide rod; 622. Arc rotating block; 63. Drive plate; 631. Drive groove; 632. Arc block; 633. Annular hydraulic rod; 7. Push plate. DETAILED DESCRIPTION

[0031] See also Figure 1 to Figure 7In an embodiment of the present invention, a pressure-maintaining coring field gas content testing device includes a pressure-maintaining outer cylinder 1, a spacing cylinder 2, a spacing plate 3, a sealing slip ring 4, an adjusting mechanism 5, a blocking mechanism 6 and a push plate 7, wherein the pressure-maintaining outer cylinder 1 is fixedly provided with a spacing cylinder 2, and a push plate 7 is provided in the spacing cylinder 2 by slidingly driving a hydraulic rod, and the push plate 7 divides the interior of the spacing cylinder 2 into two parts and forms a coring cavity 21 at the lower part of the spacing cylinder 2, and the pressure-maintaining outer cylinder 1 is fixedly provided with a spacing plate 3, and the spacing plate 3 forms a pressure-maintaining outer cylinder 1 with the spacing cylinder 2. The annular space is divided into two parts and a measuring cavity 11 is formed on the upper part of the pressure-maintaining outer cylinder 1. The pressure-maintaining outer cylinder 1 is provided with a scale line at one end of the measuring cavity 11. A sealing slip ring 4 is provided in a sealing and sliding manner in the measuring cavity 11. A distance sensor is embedded in the sealing slip ring 4. An adjusting mechanism 5 is also provided in a sliding manner in the measuring cavity 11, and the sealing slip ring 4 can push the adjusting mechanism 5 to slide. A blocking mechanism 7 is fixedly provided at the bottom of the pressure-maintaining outer cylinder 1. A plurality of supporting ears 22 are fixedly provided on the outer side of the coring cavity 21 in a circumferential manner.

[0032] The adjustment mechanism 5 includes a slide bar 51, a connecting ring 52, an adjustment plate 1 53 and an adjustment plate 2 54, wherein the connecting ring 52 is provided with two, and a plurality of adjustment plates 1 53 and adjustment plates 2 54 are fixedly arranged on the two connecting rings 52 in a circumferential manner, and the two connecting rings 52 are fixedly connected by a plurality of slide bars 51;

[0033] The spacer cylinder 2 is provided with a plurality of circumferentially-shaped sliding grooves 23 for the sliding rod 51 to seal and slide;

[0034] A plurality of sealing grooves 31 are circumferentially formed on one side of the partition plate 3 close to the measuring cavity 11, and the adjusting plate 53 slides along the sealing grooves 31 in a sealing manner;

[0035] The pressure-maintaining outer cylinder 1 is provided with a plurality of sealing grooves 12 on one side thereof close to the measuring chamber 11, and the regulating plate 54 slides sealingly along the sealing grooves 12;

[0036] The measuring cavity 11 has a plurality of air outlet holes 111 and air inlet holes 112 formed in a circular pattern at the upper and lower ends thereof;

[0037] The regulating plate 1 53 is provided with an L-shaped air inlet 1 531 and an air outlet 1 532 which are staggered and arranged, and the air inlet 1 531 and the air outlet 1 532 can be respectively communicated with the air outlet 111 and the air inlet 112 located at the lower end of the measuring cavity 11;

[0038] The second adjustment plate 54 is provided with an L-shaped second air inlet 541 and a second air outlet 542 which are staggered. The second air inlet 541 and the second air outlet 542 can be connected to the air outlet hole 111 and the air inlet hole 112 located at the upper end of the measuring cavity 11, respectively.

[0039] The coring cavity 21 is provided with a plurality of through holes 211;

[0040] The spacer tube 2 is provided with a plurality of air passages 24 , and the air passages 24 are connected to the plurality of through holes 211 and the air inlet holes 111 .

[0041] During implementation, the core is cored through the coring chamber 21, and after the core enters the coring chamber 21, the coring chamber 21 is sealed by the sealing mechanism 6, and then the pressure-maintaining outer cylinder 1 is transported as a whole to the ground to test the gas content of the core. During this process, before the core enters the coring chamber 21 and enters the coring chamber 21, the free gas emitted from the core can enter the air passage 24 through the multiple through holes 211, and then enter the measuring chamber 11 through the air passage 24, and in the process of entering the measuring chamber 11, it can selectively enter from the air inlet 1 531 or the air inlet 2 541 through the sealing slip ring 4 and the adjusting mechanism 5. In the initial state, the sealing slip ring 4 is located at the The bottom of the measuring chamber 11, at this time, the adjusting plate 1 53 is completely stuck in the sealing groove 1 31, and the air inlet 1 531 is connected with the air inlet hole 112 located at the bottom of the measuring chamber 11, and the air outlet 2 542 is connected with the air outlet hole 111 located at the top of the measuring chamber 11, and the air inlet 2 541 and the air outlet 1 532 are in a closed state, and then the free gas enters the measuring chamber 11 from the air inlet 1 531 and pushes the sealing slip ring 4 to slide upward along the measuring chamber 11 in a sealed manner. When the sealing slip ring 4 slides upward and presses on the adjusting plate 2 54, it can push the entire adjusting mechanism 5 to slide upward synchronously. In this process, the adjusting plate 1 53 slides along the sealing groove 31 and the The regulating plate 1 53 can block the air inlet 112 at the bottom of the measuring chamber 11, and make the air outlet 1 532 communicate with the air outlet 111 at the bottom of the measuring chamber 11, the regulating plate 2 53 slides along the sealing groove 2 12 and the regulating plate 2 54 can block the air outlet 111 at the top of the measuring chamber 11, and make the air inlet 2 541 communicate with the air inlet 112 at the top of the measuring chamber 11, then the free gas enters from the air inlet 112 at the top of the measuring chamber 11 and pushes the sealing slip ring 4 to slide downward, similarly, when the sealing slip ring 4 is pressed against the regulating plate 1 53, it also drives the entire regulating mechanism 5 to slide downward, at this time, the free gas is again discharged from the air inlet 112 at the bottom of the measuring chamber 11 The air hole 112 enters and pushes the sealing slip ring 4 to slide upward, and the cycle is repeated until the core is transferred to the desorption tank. In the process of the sealing slip ring 4 sliding back and forth along the measuring cavity 11, the distance sensor embedded in the sealing slip ring 4 can monitor the distance between the sealing slip ring 4 and the partition plate 3 in real time, and calculate the number of times the sealing slip ring 4 slides up and down according to the law of distance change, and then read the scale value of the last sliding position of the sealing slip ring 4 after the core is transferred to the desorption tank, so as to accurately measure the lost gas content, and then add the desorbed gas content and the residual gas content to obtain the total gas content of the core, so that the measured core gas content value is more accurate, providing an experimental basis for subsequent mining work.

[0042] In this embodiment, Figure 7 The blocking mechanism 6 includes a blocking seat 61, a sealing plate 62 and a driving plate 63, wherein the blocking seat 61 is fixedly arranged at the bottom of the pressure-maintaining outer cylinder 1, and a sealing rotation groove 611 is opened on the blocking seat 61, six sealing plates 62 are arranged in a circumferential sealing rotation in the sealing rotation groove 611, and a driving plate 63 is arranged in a circular rotation in the sealing rotation groove 611;

[0043] The sealing plate 62 is fixedly provided with a guide rod 621, and the driving plate 63 is circumferentially provided with six driving grooves 631, along which the guide rod 621 slides;

[0044] The sealing plate 62 is a triangular arc plate, and an arc-shaped rotating block 622 is fixedly arranged at the bottom of the sealing plate 62, and the circular shape of the arc-shaped rotating block 622 is located on a vertical side of the sealing plate 62, and the two arc-shaped sides of the sealing plate 62 close to the inner side of the coring cavity 21 are respectively provided with upward and downward inclined push surfaces;

[0045] In particular, upward and downward inclined push surfaces are respectively provided on the two arc-shaped edges of the sealing plate 62 so that when the sealing plate 62 is rotated to seal the coring cavity 21, two adjacent sealing plates 62 can cut the core through an upper inclined surface and a lower inclined surface, and push the core after cutting, thereby ensuring that the core is taken out as it is and preventing the core from being stuck on the sealing plate 62, that is, ensuring that the sealing plate 62 can effectively block the coring cavity 21;

[0046] The sealing rotating groove 611 is provided with six arc-shaped rotating grooves in a circumferential manner, and the arc-shaped rotating block 622 rotates along the arc-shaped rotating grooves;

[0047] The sealing rotating groove 611 is provided with an arc groove 612, and the arc groove 612 is provided with an annular hydraulic cavity;

[0048] An arc block 632 is fixedly provided on the driving plate 63 , and an annular hydraulic rod 633 is fixedly provided on the arc block 632 . The arc block 632 slides along the arc groove 612 , and the annular hydraulic rod 633 slides along the annular hydraulic chamber in a sealed manner.

[0049] In particular, the driving plate 63 is driven to rotate by hydraulic pressure, so that the rotation of the sealing plate 62 is more stable and convenient, and has a stronger driving force, ensuring that the sealing plate 62 can cut the core.

[0050] In summary, when the present invention is implemented, the free gas content of the core before it is transported to the desorption tank can be accurately measured by setting the measuring chamber 11, the adjustment mechanism 5 and the sealing slip ring 4, so that the value of the total gas content of the core in the final test is more accurate, and the pressure-maintaining outer cylinder 1 can be transported to any depth for coring, and the lost gas content of any core can be accurately measured, so that the application range of the pressure-maintaining outer cylinder 1 and the entire device is wider and the measured gas content data is more accurate.

[0051] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A pressure-maintaining coring on-site gas content testing device, characterized in that: The invention comprises a pressure-maintaining outer cylinder (1), a spacing cylinder (2), a spacing plate (3), a sealing slip ring (4), an adjusting mechanism (5), a blocking mechanism (6) and a push plate (7), wherein the pressure-maintaining outer cylinder (1) is fixedly provided with a spacing cylinder (2), the spacing cylinder (2) is driven to slide by a hydraulic rod and is provided with a push plate (7), the push plate (7) divides the interior of the spacing cylinder (2) into two parts and forms a core-taking cavity (21) at the lower part of the spacing cylinder (2), and the pressure-maintaining outer cylinder (1) is fixedly provided with a spacing plate (3), the spacing plate (3) separates the annular space formed by the pressure-maintaining outer cylinder (1) and the spacing cylinder (2) The pressure-retaining outer cylinder (1) is divided into two parts and a measuring cavity (11) is formed on the upper part of the pressure-retaining outer cylinder (1); a scale line is provided at one end of the pressure-retaining outer cylinder (1) located in the measuring cavity (11); a sealing slip ring (4) is provided in a sealing and sliding manner in the measuring cavity (11); a distance sensor is embedded in the sealing slip ring (4); an adjustment mechanism (5) is also provided in a sliding manner in the measuring cavity (11); and the sealing slip ring (4) is capable of pushing the adjustment mechanism (5) to slide; a blocking mechanism (7) is fixedly provided at the bottom of the pressure-retaining outer cylinder (1); and a plurality of support ears (22) are fixedly provided in a circumferential manner on the outer side of the coring cavity (21).

2. A pressure-maintained coring on-site gas content testing device according to claim 1, characterized in that: The adjustment mechanism (5) comprises a slide bar (51), a connecting ring (52), an adjustment plate 1 (53) and an adjustment plate 2 (54), wherein the connecting ring (52) is provided with two, and a plurality of adjustment plates 1 (53) and adjustment plates 2 (54) are respectively fixedly arranged in a circumferential manner on the two connecting rings (52), and the two connecting rings (52) are fixedly connected via a plurality of slide bars (51); Furthermore, a plurality of sliding grooves (23) for sealing and sliding of the sliding rod (51) are circumferentially provided on the spacer cylinder (2).

3. A pressure-maintained coring on-site gas content testing device according to claim 2, characterized in that: A plurality of sealing grooves (31) are circumferentially formed on one side of the partition plate (3) close to the measuring cavity (11), and the adjustment plate (53) slides sealingly along the sealing grooves (31); A plurality of sealing grooves (12) are circumferentially formed on one side of the pressure-maintaining outer cylinder (1) close to the measuring chamber (11), and the regulating plate (54) slides sealingly along the sealing grooves (12).

4. The pressure-maintaining coring on-site gas content testing device according to claim 3 is characterized in that: The measuring cavity (11) is provided with a plurality of air outlet holes (111) and air inlet holes (112) in a circular pattern at the upper and lower ends thereof; The regulating plate 1 (53) is provided with an L-shaped air inlet 1 (531) and an air outlet 1 (532) which are staggered, and the air inlet 1 (531) and the air outlet 1 (532) can be respectively communicated with the air outlet hole (111) and the air inlet hole (112) located at the lower end of the measuring cavity (11); The second regulating plate (54) is provided with an L-shaped and staggered air inlet (541) and an air outlet (542), and the second air inlet (541) and the second air outlet (542) can be respectively connected to the air outlet hole (111) and the air inlet hole (112) located at the upper end of the measuring cavity (11).

5. The pressure-maintaining coring on-site gas content testing device according to claim 1, characterized in that: The coring cavity (21) is provided with a plurality of through holes (211); The spacer cylinder (2) is provided with a plurality of air passages (24), and the air passages (24) are in communication with the plurality of through holes (211) and the air inlet hole (111).

6. The pressure-maintaining coring on-site gas content testing device according to claim 1, characterized in that: The blocking mechanism (6) comprises a blocking seat (61), a sealing plate (62) and a driving plate (63), wherein the blocking seat (61) is fixedly arranged at the bottom of the pressure-maintaining outer cylinder (1), a sealing rotation groove (611) is provided on the blocking seat (61), six sealing plates (62) are arranged in a circular sealing rotation in the sealing rotation groove (611), and a driving plate (63) is arranged in a circular rotation in the sealing rotation groove (611); A guide rod (621) is fixedly arranged on the sealing plate (62), and six drive grooves (631) are circumferentially formed on the drive plate (63), and the guide rod (621) slides along the drive grooves (631).

7. The pressure-maintaining coring on-site gas content testing device according to claim 6, characterized in that: The sealing plate (62) is a triangular arc-shaped plate, an arc-shaped rotating block (622) is fixedly arranged at the bottom of the sealing plate (62), and the circular shape of the arc-shaped rotating block (622) is located on a vertical side of the sealing plate (62), and the two arc-shaped sides of the sealing plate (62) close to the inner side of the coring cavity (21) are respectively provided with upward and downward inclined push surfaces; The sealing rotation groove (611) is provided with six arc-shaped rotation grooves in a circumferential manner, and the arc-shaped rotation block (622) rotates along the arc-shaped rotation grooves.

8. The pressure-maintaining coring on-site gas content testing device according to claim 6, characterized in that: The sealing rotating groove (611) is provided with an arc-shaped groove (612), and the arc-shaped groove (612) is provided with an annular hydraulic cavity; An arc block (632) is fixedly provided on the driving plate (63), an annular hydraulic rod (633) is fixedly provided on the arc block (632), the arc block (632) slides along the arc groove (612), and the annular hydraulic rod (633) slides in a sealed manner along the annular hydraulic chamber.

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