CN109723622B - Retaining free piston - Google Patents
Retaining free piston Download PDFInfo
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- CN109723622B CN109723622B CN201811500352.8A CN201811500352A CN109723622B CN 109723622 B CN109723622 B CN 109723622B CN 201811500352 A CN201811500352 A CN 201811500352A CN 109723622 B CN109723622 B CN 109723622B
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- shaped friction
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Abstract
A retaining free piston relates to the field of wind tunnel operation control; the anti-locking piston comprises a rear support ring, a piston body, an anti-falling gland, an anti-falling pin, a return spring, n wedge-shaped friction blocks, an anti-locking push rod, a front support ring, a push rod gland and a gland pull ring; the rear support ring and the front support ring are respectively sleeved on the side walls at two axial ends of the piston body; the n wedge-shaped friction blocks are uniformly and annularly distributed on the outer side wall of the axial middle part of the piston body; the anti-drop pin is coaxially and fixedly arranged at the butt joint of the piston body and the wedge-shaped friction block; the reset spring is sleeved on the outer wall of the anti-drop pin; the anti-falling gland is fixedly arranged on the radial outer side of the anti-falling pin; the anti-locking push rod axially extends into the piston body from the axial front end of the piston body; the push rod gland is fixedly arranged at the axial outer end of the anti-locking push rod; the gland pull ring axially extends into the piston body from the axial front end of the piston body; the invention improves the safety of the operation of the piston compressor, improves the compression efficiency and increases the effective operation time of the wind tunnel by the retaining action.
Description
Technical Field
The invention relates to the field of wind tunnel operation control, in particular to a backstop type free piston.
Background
In the free piston shock wave wind tunnel, a free piston running at high speed in a compression pipe is a core component of a wind tunnel driving section and is used for forward compression to generate high-temperature high-pressure gas meeting the test requirements. When the free piston runs to the tail end of the compression pipe, rebound movement sometimes occurs due to large pressure at the front end, and when the free piston accelerates forward movement under the action of pressure at the rear end again after rebounding for a certain distance, the tail end of the piston is greatly accelerated due to the fact that front end gas flows into the shock tube, and safe running and buffer stop of the piston are not facilitated. Meanwhile, the efficiency of the piston compressor is reduced due to the too fast rebound of the piston, the effective driving time is shortened, and the test capability of the wind tunnel is influenced.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a backstop type free piston, which improves the operation safety of a piston compressor, improves the compression efficiency and increases the effective operation time of a wind tunnel through a backstop effect.
The above purpose of the invention is realized by the following technical scheme:
a non-return free piston comprises a rear support ring, a piston body, an anti-drop gland, an anti-drop pin, a reset spring, n wedge-shaped friction blocks, an anti-locking push rod, a front support ring, a push rod gland and a gland pull ring; wherein, the piston body is a hollow columnar structure; the rear supporting ring is sleeved on the side wall at the rear end of the piston body; the front support ring is sleeved on the side wall of the front end of the piston body shaft; the n wedge-shaped friction blocks are uniformly and annularly distributed on the outer side wall of the axial middle part of the piston body; the anti-drop pin is of a rod-shaped structure and is coaxially and fixedly arranged at the butt joint of the piston body and the wedge-shaped friction block; each wedge-shaped friction block corresponds to 1 anti-drop pin; one axial end of the anti-drop pin extends into the wedge-shaped friction block; the reset spring is sleeved on the outer wall of the anti-drop pin; the anti-falling gland is fixedly arranged on the radial outer side of the anti-falling pin; the anti-locking push rod is of a rod-shaped structure; the anti-locking push rod axially extends into the piston body from the axial front end of the piston body; the axial inner end of the anti-locking push rod is in contact with the wedge-shaped friction block, and the axial outer end of the anti-locking push rod extends out of the front support ring; the push rod gland is of a circular plate-shaped structure; the push rod gland is fixedly arranged at the axial outer end of the anti-locking push rod; the gland pull ring axially extends into the piston body from the axial front end of the piston body; the gland pull ring is positioned at the axis position of the piston body; n is a positive integer; the outer compression pipe is sleeved on the outer wall of the backstop type free piston.
In the above-described retaining free piston, n is 3 or more.
In the above retaining free piston, the piston body is made of aluminum alloy or alloy steel.
In the retaining free piston, the section of the wedge-shaped friction block along the radial direction of the piston body is in an inverted trapezoid shape; the inner wall of the wedge-shaped friction block, which is contacted with the outer side wall of the piston body, is a smooth surface; the outer wall of the wedge-shaped friction block, which is contacted with the inner wall of the external compression pipe, is an arc surface.
In the retaining free piston, the anti-falling pin mounting hole is formed in the side wall of the right angle side of the inverted trapezoidal wedge-shaped friction block, so that one axial end of the anti-falling pin extends into the anti-falling pin mounting hole; the bevel side wall of the inverted trapezoidal wedge-shaped friction block is provided with a push rod mounting hole, so that the axial end of the locking-preventing push rod can stretch into the push rod.
In the retaining free piston, n friction block mounting grooves are formed in the outer wall of the middle of the piston body and correspond to the wedge-shaped friction blocks; the bottom of the friction block mounting groove is a straight inclined plane corresponding to the wedge-shaped friction block; the wedge-shaped friction block is installed in the friction block installation groove.
In the retaining free piston, the anti-drop gland compresses all the anti-drop pins which are uniformly distributed, so that all the wedge-shaped friction blocks are simultaneously pressed by the anti-drop pins.
In the retaining free piston, the return spring keeps the wedge-shaped friction block attached to the straight inclined surface of the friction block mounting groove in the running process of the piston body inside the external compression pipe.
In the above-mentioned retaining free piston, the working process of the retaining free piston is as follows:
the free piston runs along the inner wall of the external compression pipe in the free piston shock tunnel; the wedge-shaped friction block is semi-fixed on the side wall of the piston body; when the piston runs in the reverse direction, the wedge-shaped friction block moves along the inclined surface of the friction block mounting groove and is pressed between the piston body and the inner wall of the external compression pipe, and the retaining effect is formed through the generated pressing force and friction force.
In the above-mentioned retaining free piston, the rear support ring and the front support ring are made of teflon.
Compared with the prior art, the invention has the following advantages:
(1) the wedge-shaped friction block is of a thin structure, so that the shearing force resistant area is increased, and the strength of a monomer is increased;
(2) the wedge-shaped friction blocks are distributed circumferentially, so that the load borne by each friction block is reduced, and the reliability of the system is improved;
(3) the wedge-shaped friction block has a simple structure, is low in manufacturing cost and convenient to replace, and can replace the worn friction block according to the wear condition, so that the use efficiency is improved;
(4) the partial retaining structure is arranged on the piston body, the depth of the groove is shallow, and the strength of the piston body can be ensured under the condition that the weight of the piston is not greatly improved; meanwhile, no fastener which needs to bear large load is arranged, and the integral reliability of the component is improved.
Drawings
FIG. 1 is a schematic view of a structure of a non-return free piston according to the present invention;
FIG. 2 is a schematic view of the wedge-shaped friction block of the present invention;
FIG. 3 is a schematic view of a friction block mounting groove of the present invention;
FIG. 4 is a schematic view of the wedge-shaped friction block of the present invention.
Detailed Description
The invention is described in further detail below with reference to the following figures and specific examples:
the invention provides a free piston with a backstop function, which can prevent the excessive acceleration speed of the rebound free piston, damage to a tail end buffer structure and a piston body structure and guarantee the safe operation of a free piston shock tunnel.
As shown in fig. 1, which is a schematic structural diagram of a retaining free piston, it can be known that the retaining free piston includes a rear support ring 1, a piston body 2, an anti-drop gland 3, an anti-drop pin 4, a return spring 5, n wedge-shaped friction blocks 6, an anti-locking push rod 7, a front support ring 8, a push rod gland 9 and a gland pull ring 10; wherein, the piston body 2 is a hollow columnar structure; the rear supporting ring 1 is sleeved on the side wall of the axial rear end of the piston body 2; the front support ring 8 is sleeved on the side wall of the axial front end of the piston body 2; n wedge-shaped friction blocks 6 are uniformly and annularly distributed on the outer side wall of the axial middle part of the piston body 2; the anti-falling pin 4 is of a rod-shaped structure, and the anti-falling pin 4 is coaxially and fixedly arranged at the butt joint of the piston body 2 and the wedge-shaped friction block 6; each wedge-shaped friction block 6 corresponds to 1 anti-falling pin 4; one axial end of the anti-falling pin 4 extends into the wedge-shaped friction block 6; the reset spring 5 is sleeved on the outer wall of the anti-falling pin 4; the anti-falling gland 3 is fixedly arranged at the radial outer side of the anti-falling pin 4; the anti-locking push rod 7 is of a rod-shaped structure; the anti-locking push rod 7 axially extends into the piston body 2 from the axial front end of the piston body 2; the axial inner end of the anti-locking push rod 7 is contacted with the wedge-shaped friction block 6, and the axial outer end of the anti-locking push rod 7 extends out of the front support ring 8; the push rod gland 9 is of a circular plate-shaped structure; the push rod gland 9 is fixedly arranged at the axial outer end of the anti-locking push rod 7; the gland pull ring 10 axially extends into the piston body 2 from the axial front end of the piston body 2; the gland pull ring 10 is positioned at the axis position of the piston body 2; n is a positive integer, and n is greater than or equal to 3; the outer compression tube 11 is fitted around the outer wall of the backstop free piston. The piston body 2 is made of aluminum alloy or alloy steel. The rear support ring 1 and the front support ring 8 are made of polytetrafluoroethylene materials.
As shown in fig. 2, the wedge-shaped friction block has a schematic structure, and it can be seen that the section of the wedge-shaped friction block 6 along the radial direction of the piston body 2 is an inverted trapezoid shape; the inner wall of the wedge-shaped friction block 6, which is contacted with the outer side wall of the piston body 2, is a smooth surface; the outer wall of the wedge-shaped friction block 6, which is contacted with the inner wall of the outer compression pipe 11, is a circular arc surface. The anti-falling pin mounting hole 61 is formed in the side wall of the right-angle side of the inverted trapezoidal wedge-shaped friction block 6, so that the anti-falling pin 4 can extend into one axial end; the side wall of the bevel edge of the inverted trapezoidal wedge-shaped friction block 6 is provided with a push rod mounting hole 62, so that the axial end of the locking push rod 7 is prevented from extending into the side wall. The contact surface of the wedge-shaped friction block 6 and the piston body 2 is a plane, and the contact surface of the wedge-shaped friction block and the inner wall of the outer compression pipe 11 is an arc surface with the diameter same as the inner diameter of the outer compression pipe 11; the back end face of the wedge-shaped friction block 6 is provided with a mounting hole for preventing the pin from falling off, and the inclined plane at the front end is provided with a blind hole matched with the locking push rod.
As shown in fig. 3, which is a schematic view of the friction block mounting groove of the present invention, it can be seen that n friction block mounting grooves 21 are formed at the outer wall of the middle portion of the piston body 2 corresponding to the positions of the wedge-shaped friction blocks 6; the bottom of the friction block mounting groove 21 is a straight inclined surface corresponding to the wedge-shaped friction block 6; the wedge-shaped friction block 6 is installed in the friction block installation groove 21. The anti-falling gland 3 compresses all the anti-falling pins 4 which are uniformly distributed, so that all the wedge-shaped friction blocks 6 are simultaneously pressed by the anti-falling pins 4.
The anti-drop pin 4 is fixed in a pin hole at the rear end of the wedge-shaped friction block 6, the outer side of the anti-drop pin is sleeved with the return spring 5, and then the anti-drop pin is integrally arranged in a friction block mounting groove 21 on the outer peripheral surface of the piston body 2; the anti-drop gland 3 fixed on the piston body 2 is used for pressing the anti-drop pin 4 and the return spring 5; the anti-drop pin 4 is used for preventing the wedge-shaped friction block 6 from dropping off in the carrying process of the piston, the return spring 5 is used for keeping the piston in the operation process, and the wedge-shaped friction block 6 can be attached to the matched inclined plane of the piston body 2. The return spring 5 keeps the wedge-shaped friction block 6 attached to the straight inclined surface of the friction block mounting groove 21 in the process that the piston body 2 runs inside the external compression pipe 11.
As shown in fig. 4, which is a schematic diagram of the wedge-shaped friction block, it can be known that the working process of the backstop free piston is as follows:
the free piston runs along the inner wall of the external compression pipe 11 in the free piston shock tunnel; the wedge-shaped friction block 6 is semi-fixed on the side wall of the piston body 2; when operating in the reverse direction, the wedge-shaped friction block 6 moves along the inclined surface of the friction block mounting groove 21, is compressed between the piston body 2 and the inner wall of the outer compression tube 11, and forms a backstop action by the generated compression force and friction force.
Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.
Claims (10)
1. A retaining free piston comprises a piston body (2), a return spring (5) and n wedge-shaped friction blocks (6); n wedge-shaped friction blocks (6) are uniformly and annularly distributed on the outer side wall of the axial middle part of the piston body (2); the method is characterized in that: the backstop type free piston also comprises a rear support ring (1), an anti-drop gland (3), an anti-drop pin (4), an anti-locking push rod (7), a front support ring (8), a push rod gland (9) and a gland pull ring (10); wherein, the piston body (2) is a hollow columnar structure; the rear supporting ring (1) is sleeved on the side wall of the axial rear end of the piston body (2); the front support ring (8) is sleeved on the side wall of the axial front end of the piston body (2); the anti-dropping pin (4) is of a rod-shaped structure, and the anti-dropping pin (4) is coaxially and fixedly arranged at the butt joint of the piston body (2) and the wedge-shaped friction block (6); each wedge-shaped friction block (6) corresponds to 1 anti-falling pin (4); one axial end of the anti-falling pin (4) extends into the wedge-shaped friction block (6); the reset spring (5) is sleeved on the outer wall of the anti-drop pin (4); the anti-falling gland (3) is fixedly arranged at the radial outer side of the anti-falling pin (4); the anti-locking push rod (7) is of a rod-shaped structure; the anti-locking push rod (7) axially extends into the piston body (2) from the axial front end of the piston body (2); the axial inner end of the anti-locking push rod (7) is contacted with the wedge-shaped friction block (6), and the axial outer end of the anti-locking push rod (7) extends out of the front support ring (8); the push rod gland (9) is of a circular plate-shaped structure; the push rod gland (9) is fixedly arranged at the axial outer end of the anti-locking push rod (7); the gland pull ring (10) axially extends into the piston body (2) from the axial front end of the piston body (2); the gland pull ring (10) is positioned at the axis position of the piston body (2); n is a positive integer; an outer compression pipe (11) is sleeved on the outer wall of the backstop type free piston.
2. A backstop free piston according to claim 1, characterized in that: and n is greater than or equal to 3.
3. A backstop free piston according to claim 2, characterized in that: the piston body (2) is made of aluminum alloy or alloy steel.
4. A backstop free piston according to claim 3, characterized in that: the section of the wedge-shaped friction block (6) along the radial direction of the piston body (2) is in an inverted trapezoid shape; the inner wall of the wedge-shaped friction block (6) which is contacted with the outer side wall of the piston body (2) is a smooth surface; the outer wall of the wedge-shaped friction block (6) contacted with the inner wall of the external compression pipe (11) is a circular arc surface.
5. A check type free piston according to claim 4, characterized in that: an anti-falling pin mounting hole (61) is formed in the side wall of the right-angle side of the inverted trapezoidal wedge-shaped friction block (6), so that one axial end of the anti-falling pin (4) can extend into the anti-falling pin mounting hole; the side wall of the bevel edge of the inverted trapezoidal wedge-shaped friction block (6) is provided with a push rod mounting hole (62), so that the axial end of the locking push rod (7) is prevented from extending into the side wall.
6. A check type free piston according to claim 5, characterized in that: n friction block mounting grooves (21) are formed in the outer wall of the middle of the piston body (2) and correspond to the wedge-shaped friction blocks (6); the bottom of the friction block mounting groove (21) is a straight inclined surface corresponding to the wedge-shaped friction block (6); the wedge-shaped friction block (6) is installed in the friction block installation groove (21).
7. A backstop free piston according to claim 6, characterized in that: the anti-falling gland (3) compresses all the anti-falling pins (4) which are uniformly distributed, so that all the wedge-shaped friction blocks (6) are simultaneously pressed by the anti-falling pins (4).
8. A backstop free piston according to claim 7, characterized in that: the reset spring (5) keeps the straight inclined plane of the wedge-shaped friction block (6) and the friction block mounting groove (21) attached in the process that the piston body (2) runs inside the external compression pipe (11).
9. A backstop free piston according to claim 8, characterized in that: the working process of the retaining free piston is as follows:
the free piston runs along the inner wall of the external compression pipe (11) in the free piston shock tunnel; the wedge-shaped friction block (6) is semi-fixed on the side wall of the piston body (2); when the piston runs in the reverse direction, the wedge-shaped friction block (6) moves along the inclined surface of the friction block mounting groove (21) and is pressed between the piston body (2) and the inner wall of the outer compression pipe (11), and the retaining effect is formed by the generated pressing force and friction force.
10. A backstop free piston according to claim 9, characterized in that: the rear supporting ring (1) and the front supporting ring (8) are made of polytetrafluoroethylene materials.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811500352.8A CN109723622B (en) | 2018-12-07 | 2018-12-07 | Retaining free piston |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811500352.8A CN109723622B (en) | 2018-12-07 | 2018-12-07 | Retaining free piston |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109723622A CN109723622A (en) | 2019-05-07 |
| CN109723622B true CN109723622B (en) | 2020-04-10 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811500352.8A Active CN109723622B (en) | 2018-12-07 | 2018-12-07 | Retaining free piston |
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| Country | Link |
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| CN (1) | CN109723622B (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07243935A (en) * | 1994-03-09 | 1995-09-19 | Hitachi Ltd | Free piston type wind tunnel device |
| CN201613275U (en) * | 2010-04-02 | 2010-10-27 | 天津三英焊业股份有限公司 | Stretching device |
| CN206513713U (en) * | 2017-03-02 | 2017-09-22 | 宜昌长机科技有限责任公司 | One kind linear motion clamp system |
| CN107152997A (en) * | 2017-06-29 | 2017-09-12 | 中国空气动力研究与发展中心超高速空气动力研究所 | A kind of rolling support piston |
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2018
- 2018-12-07 CN CN201811500352.8A patent/CN109723622B/en active Active
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| CN109723622A (en) | 2019-05-07 |
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