CN112302913A

CN112302913A - Corrugated pipe pump with embedded LVDT displacement sensor

Info

Publication number: CN112302913A
Application number: CN202011162498.3A
Authority: CN
Inventors: 阮晓东; 葛天怿; 胡亮; 付新; 苏芮
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2020-10-27
Filing date: 2020-10-27
Publication date: 2021-02-02

Abstract

The invention provides a bellows pump with an embedded LVDT displacement sensor. The position of the corrugated pipe is detected by using the LVDT displacement sensor, and the method has the advantages of high precision, stable performance, high response speed, large linear range, large output, convenience in use and the like; the LVDT displacement sensor is integrated into the pump body, so that the problems of abrasion, falling or fracture of the measuring rod and the like caused by vibration and non-concentricity in installation of the externally-mounted LVDT are effectively avoided, the working stability of the sensor is effectively improved, and the service life of the sensor is prolonged; meanwhile, the invention integrates the existing bellows pump structure and the LVDT measurement principle, realizes the high integration of the displacement detection module and the pump body, and makes the whole pump structure more compact.

Description

Corrugated pipe pump with embedded LVDT displacement sensor

Technical Field

The invention relates to the technical field of bellows pumps, in particular to a bellows pump with an embedded LVDT displacement sensor.

Background

In the fields of semiconductor manufacturing, high-purity chemical industry, biomedicine, and the like, there are many cases where it is necessary to use a high-purity fluid. As a fluid power source, the bellows pump has the characteristic of less pollution, and is widely applied to high-purity fluid systems. The basic principle of a bellows pump is to create a periodic fluid driving force by either drawing fluid from a conduit into the pump chamber or forcing fluid from the pump chamber into a conduit by changing the volume of a flexible pump chamber. Because the power generation mode comes from the deformation of the pump cavity, no sliding friction is generated, so that no pollution particles are generated due to friction, no pollutants migrate into the pump cavity from the sliding gap due to the existence of the sliding kinematic pair, the source of the pollutants is obviously reduced, and the high-purity fluid component is particularly suitable for high-purity fluid systems.

The most basic bellows pump has a bellows disposed on the pump head, the bellows forming a pump chamber therein; the pump head is provided with a fluid inflow channel and a fluid outflow channel, and the fluid inflow channel and the fluid outflow channel are respectively communicated with the pump cavity through one-way valves; when the bellows is stretched or compressed, fluid is drawn into and expelled from the pump chamber, respectively, creating an outwardly pumped fluid flow. In order to monitor and adjust the output characteristics of a bellows pump, a sensor is required to monitor the position of the bellows. In order to obtain higher measurement accuracy and more compact size, the conventional bellows pump adopts a laser displacement sensor to detect the displacement of a moving part of the bellows pump. However, the cost of the laser displacement sensor is high, and the response speed is not fast enough. An LVDT (Linear Variable Differential Transformer) displacement sensor is another position detection sensor, but the existing pen type LVDT displacement sensor is installed behind a bellows pump, so that the bellows pump is oversized, certain vibration exists in the operation process of the bellows pump, the externally installed LVDT is difficult to ensure that a measuring rod and a coil are completely concentric, after the measuring rod reciprocates for a long time, the LVDT is loosened or abraded, the LVDT coil is directly abraded or even damaged, and in serious cases, faults such as falling or breaking of the LVDT measuring rod occur, and equipment damage is caused.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a bellows pump with an embedded LVDT displacement sensor. The LVDT displacement sensor is integrated into the pump body to monitor the displacement of the corrugated pipe, so that the accuracy, response speed and reliability of corrugated pipe displacement monitoring are improved, and the compact volume of the corrugated pipe pump is kept.

The invention comprises a pump head, a corrugated pipe, a pump shaft and a displacement sensor; the pair of corrugated pipes are symmetrically arranged on two sides of the pump head, and a pump cavity is formed in each corrugated pipe; the pump casings are symmetrically arranged on two sides of the pump head and are respectively arranged outside the corrugated pipes, and air chambers are formed outside the corrugated pipes and inside the pump casings; one end of the corrugated pipe, which is far away from the pump head, is connected with a pump shaft, the pump shaft penetrates through the air chamber and the pump shell and extends out of the pump shell, and the pump shafts of the corrugated pipes on the two sides are connected through a connecting rod; a guide sleeve and a sealing ring are arranged at the joint of the pump shell and the pump shaft and are respectively used for radial positioning and motion sealing of the pump shaft; a first LVDT secondary winding, an LVDT primary winding and a second LVDT secondary winding are sequentially arranged in an axial space inside the pump shell and close to the pump shaft along the axial direction; an LVDT iron core is arranged inside the pump shaft; the first LVDT secondary winding and the second LVDT secondary winding are connected in series in an opposite direction on the circuit.

Further, the LVDT iron core is partially or completely overlapped with the first LVDT secondary winding, the LVDT primary winding or the second LVDT secondary winding in the axial position.

Further, the radial outer sides of the LVDT primary winding and the LVDT secondary winding are shielded by end covers made of materials with high magnetic permeability so as to achieve a magnetic shielding effect.

Preferably, the LVDT iron core is wrapped inside the pump shaft in an injection molding mode.

Furthermore, a threaded hole is machined in one side, close to the corrugated pipe, of the pump shaft, the LVDT iron core is placed into the threaded hole, and the LVDT iron core is fixed through a set screw.

Further, the connecting rod includes left connecting rod and right connecting rod, connects through flexible link gear between left connecting rod and the right connecting rod.

Preferably, the flexible linkage comprises a spring or a compression air spring.

Further, at least one of the bellows is under continuous compression while pumping the fluid.

Further, when pumping the fluid, there is a process of supplying compressed air to both side air chambers at the same time.

The invention provides a bellows pump embedded with an LVDT displacement sensor, which utilizes the LVDT displacement sensor to detect the position of a bellows and has the advantages of higher precision, stable performance, high response speed, large linear range, large output, convenient use and the like; the LVDT displacement sensor is integrated into the pump body, so that the problems of abrasion, falling or fracture of the measuring rod and the like caused by vibration and non-concentricity in installation of the externally-mounted LVDT are effectively avoided, the working stability of the sensor is effectively improved, and the service life of the sensor is prolonged; meanwhile, the invention integrates the existing bellows pump structure and the LVDT measurement principle, realizes the high integration of the displacement detection module and the pump body, and makes the whole pump structure more compact.

Drawings

FIG. 1 is a front view of an embodiment of the present invention;

FIG. 2 is a front cross-sectional view of an embodiment of the present invention;

fig. 3 is a partial cross-sectional view of an LVDT displacement sensor according to an embodiment of the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

The bellows pump with the embedded LVDT displacement sensor, as shown in fig. 1, 2 and 3, includes a pump casing 4, an end plate 1, a support plate 3, a fastening rod 6, a left connecting rod 2 and a right connecting rod 5; the liquid inlet check valve further comprises a flange plate 7, a corrugated pipe 8, a liquid outlet check valve 9, a liquid outlet check valve core 10, a liquid inlet check valve 26, a liquid inlet check valve core 25, a spring shaft sleeve 11, a spring shaft 12, a spring 13, a first LVDT secondary winding 16, an end cover 17, an LVDT primary winding 18, a second LVDT secondary winding 19, a guide sleeve 20, an LVDT iron core 21, a pump shaft 22, a sealing ring 23, a pump head 24 and a set screw 27.

A pair of corrugated pipes 8 are symmetrically arranged on two side surfaces of the pump head 24, and a pump cavity 14 is formed between each corrugated pipe 8 and the pump head 24; a pair of pump housings 4 symmetrically disposed on both sides of the pump head 24 and accommodating the bellows 8; a space air chamber 15 is formed between the pump shell 4 and the corrugated pipe 8 as well as the pump head 24; the fastening rods 6 are matched with screws to tightly press the two pump shells 4 on the pump head 24; the bottom of the corrugated pipe 8 is fixed with a pump shaft 22 through a flange plate 7; the pump shaft 22 extends out of the pump shell 4 from the inside of the pump shell 4 and the air chamber 15; the left connecting rod 2 and the right connecting rod 5 are arranged outside the pump shell 4 and are respectively fixedly connected with the left end plate 1 and the right end plate 1; the left end plate 1 and the right end plate 1 are fixedly connected with a pump shaft 22; the left connecting rod 2 and the right connecting rod 5 are connected together, so that the end plates 1 and the pump shafts 22 on the left side and the right side can move in a combined manner, and the corrugated pipes 8 on the left side and the right side are driven to move in a combined manner; the left connecting rod 2 and the right connecting rod 5 can be fixedly connected, so that the corrugated pipes 8 on the left side and the right side can jointly move in opposite phases; the left connecting rod 2 and the right connecting rod 5 can also be connected through a flexible linkage mechanism as shown in fig. 2; the flexible linkage mechanism consists of a spring 13, a spring shaft 12 and a spring shaft sleeve 11; the bottom of the spring shaft sleeve 11 is provided with a limiting mechanism; the spring shaft 12 can move in a straight line in the spring shaft sleeve 11; when the spring is in a compressed state in a static state, the spring shaft 12 is limited at the bottom end of the sleeve by the limiting mechanism; the flexible linkage mechanism can also be composed of energy storage elements such as a compression air spring, a same-name magnetic pole and the like which are arranged along a straight line; through the arrangement of the flexible linkage mechanism, the phases of the corrugated pipes 8 on the left side and the right side can be staggered and are not exactly opposite, in the specific implementation process, the corrugated pipe 8 on one side is allowed to move to the limit position, the speed is reduced to zero, the corrugated pipe 8 on the other side is still in the compression stroke, and the condition that the output flow of the corrugated pipe pump is reduced to zero to cause output pulsation when the corrugated pipes 8 on the two sides are both in the limit position is avoided.

A liquid outlet one-way valve 9 and a liquid inlet one-way valve 26 are arranged in the pump head 24; the liquid outlet one-way valve 9 is communicated with the corrugated pipe 8 and the liquid outlet flow path, and a liquid outlet one-way valve core 10 of the liquid outlet one-way valve 9 allows the fluid to flow from the pump cavity 14 to the liquid outlet flow path in a one-way mode; the inlet check valve 26 communicates the bellows 8 with the inlet flow path, and the inlet check valve core 25 of the inlet check valve 26 permits one-way flow of fluid from the inlet flow path to the pump chamber 14. When the bellows pump is operated, compressed air pressure is supplied to the air chambers 15 on the left and right sides, respectively; when compressed air flows to the left air chamber 15, the pressure of the left air chamber 15 rises, the left corrugated pipe 8 moves to the right, the volume of the left pump cavity 14 is reduced, fluid media in the cavity are extruded, the pressure in the cavity rises, when the pressure in the cavity rises to a certain magnitude, the liquid outlet one-way valve 9 in the cavity is opened, and the fluid media flows out of the left pump cavity 14, so that the liquid discharging process is realized; when compressed air is supplied to the left air chamber 15, the right air chamber 15 is communicated with the atmosphere, when the left corrugated pipe 8 moves rightwards, the pump shaft 22 connected with the left corrugated pipe drives the right pump shaft 22 and the right corrugated pipe 8 to move rightwards simultaneously through the left connecting rod 2 and the right connecting rod 5, the volume of the right pump chamber 14 is increased, the pressure in the chamber is reduced, when the pressure in the chamber is reduced to a certain size, the liquid inlet one-way valve 26 in the chamber is opened, and fluid medium flows into the right pump chamber 14, which is a liquid suction process; the bellows 8 on the left and right sides continuously reciprocate to perform a suction process and a discharge process, thereby pumping fluid out of the pump body.

When the displacement of the left corrugated pipe 8 reaches a set compression extreme value, the movement speed of the left corrugated pipe 8 is reduced to zero, and the liquid discharge flow is reduced to zero; at this time, compressed air is supplied to the right air chamber 15, the pressure of the right air chamber 15 rises, the corrugated pipes 8 on the two sides are not rigidly fixed due to the arrangement of the flexible linkage mechanism, and when the corrugated pipe 8 on one side moves to the limit position, the corrugated pipe 8 on the other side is still in the compression stroke, so that the corrugated pipe on at least one side is ensured to be in the state of pumping fluid outwards, and the flow pulsation of the pumped fluid is reduced. By controlling the positions of the left and right bellows 8, the degree of overlap of the compression strokes of the bellows 8 on both sides can be adjusted, so that the bellows pump can obtain the lowest output flow pulsation under various working conditions. Therefore, it is necessary to detect the position of the bellows 8.

In an axial space inside the pump shell 4, a first LVDT secondary winding 16, an LVDT primary winding 18 and a second LVDT secondary winding 19 are sequentially arranged close to a pump shaft 22 along the axial direction, and gaps among the three windings are filled with high-density materials; the first LVDT secondary winding 16 and the second LVDT secondary winding 19 are connected in series and in reverse on the circuit; the radial outer side of the winding is shielded by an end cover 17 made of materials with high magnetic permeability such as nodular cast iron or silicon steel and the like to play a role of magnetic shielding; a guide sleeve 20 and a sealing ring 23 are arranged at the joint of the pump shell 4 and the pump shaft 22 and are used for radial positioning and motion sealing of the pump shaft 22; an LVDT iron core 21 is arranged inside the pump shaft 22, and the LVDT iron core 21 is partially or completely overlapped with the first LVDT secondary winding 16, the LVDT primary winding 18 or the second LVDT secondary winding 19 in the axial position; if the pump shaft 22 is made of plastic, the LVDT iron core 21 can be wrapped inside the pump shaft 22 in an injection molding mode; if the pump shaft 22 is made of metal, a threaded hole can be machined in the side of the pump shaft 22 near the bellows 8, the LVDT core 21 is placed into the threaded hole, and the LVDT core 21 is fixed by the set screw 27. An alternating current signal with certain frequency and amplitude is applied to the LVDT primary winding 18, due to mutual inductance effect, the first LVDT secondary winding 16 and the second LVDT secondary winding 19 can generate corresponding mutual inductance electromotive force, and the size of the mutual inductance electromotive force generated by the secondary windings is in direct proportion to the lap joint length of the windings and the LVDT iron cores 21, so that along with the movement of the LVDT iron cores 21 embedded in the pump shaft 22, the two LVDT secondary windings in series reverse can generate a signal which changes along with displacement, and the actual position of the pump shaft 22 can be obtained by processing the signal.

According to the invention, the LVDT iron core is arranged inside the pump shaft, so that the phenomenon that the pump body is oversized due to the fact that the LVDT sensor is externally arranged is avoided; the LVDT winding is arranged in the pump shell, and the winding is arranged in an axial space formed by the pump shaft guide sleeve and the sealing ring, so that the winding is prevented from enlarging the size of the pump body; the pump shaft, the pump shell and the LVDT sensor are integrated, the problems that the outer LVDT is abraded, the measuring rod falls off or is broken and the like due to vibration and non-concentricity in installation are effectively avoided, the working stability of the sensor is effectively improved, and the service life of the sensor is prolonged.

In the positional relationship description of the present invention, the appearance of terms such as "inner", "outer", "upper", "lower", "left", "right", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the drawings is merely for convenience of describing the embodiments and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation and operation, and thus, is not to be construed as limiting the present invention.

The foregoing summary and structure are provided to explain the principles, general features, and advantages of the product and to enable others skilled in the art to understand the invention. The foregoing examples and description have been presented to illustrate the principles of the invention and are intended to provide various changes and modifications within the spirit and scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. The utility model provides an embedded LVDT displacement sensor's bellows pump which characterized in that: comprises a pump head, a corrugated pipe, a pump shaft and a displacement sensor; the pair of corrugated pipes are symmetrically arranged on two sides of the pump head, and a pump cavity is formed in each corrugated pipe; the pump casings are symmetrically arranged on two sides of the pump head and are respectively arranged outside the corrugated pipes, and air chambers are formed outside the corrugated pipes and inside the pump casings; one end of the corrugated pipe, which is far away from the pump head, is connected with a pump shaft, the pump shaft penetrates through the air chamber and the pump shell and extends out of the pump shell, and the pump shafts of the corrugated pipes on the two sides are connected through a connecting rod; a guide sleeve and a sealing ring are arranged at the joint of the pump shell and the pump shaft and are respectively used for radial positioning and motion sealing of the pump shaft; a first LVDT secondary winding, an LVDT primary winding and a second LVDT secondary winding are sequentially arranged in an axial space inside the pump shell and close to the pump shaft along the axial direction; an LVDT iron core is arranged inside the pump shaft; the first LVDT secondary winding and the second LVDT secondary winding are connected in series in an opposite direction on the circuit.

2. The bellows pump of claim 1, wherein the LVDT displacement sensor is embedded in the bellows pump, and wherein: the LVDT iron core is partially or completely overlapped with the first LVDT secondary winding, the LVDT primary winding or the second LVDT secondary winding in the axial position.

3. A bellows pump with an embedded LVDT displacement sensor according to claim 1 or 2, wherein: the radial outer sides of the LVDT primary winding and the LVDT secondary winding are shielded by end covers made of materials with high magnetic permeability so as to achieve a magnetic shielding effect.

4. A bellows pump with an embedded LVDT displacement sensor according to claim 3, wherein: and the LVDT iron core is wrapped inside the pump shaft in an injection molding mode.

5. A bellows pump with an embedded LVDT displacement sensor according to claim 3, wherein: and processing a threaded hole at one side of the pump shaft close to the corrugated pipe, putting the LVDT iron core into the threaded hole, and fixing the LVDT iron core by using a set screw.

6. The bellows pump of claim 1, wherein the LVDT displacement sensor is embedded in the bellows pump, and wherein: the connecting rod includes left connecting rod and right connecting rod, connects through flexible link gear between left connecting rod and the right connecting rod.

7. The bellows pump of claim 6, wherein the LVDT displacement sensor is embedded in the bellows pump, and wherein: the flexible linkage includes a spring.

8. The bellows pump of claim 6, wherein the LVDT displacement sensor is embedded in the bellows pump, and wherein: the flexible linkage mechanism comprises a compression air spring.

9. A bellows pump with an embedded LVDT displacement sensor according to claim 7 or 8, wherein: at least one of the bellows is under continuous compression during pumping of the fluid.

10. The bellows pump of claim 9, wherein the LVDT displacement sensor is embedded in the bellows pump, further comprising: when pumping fluid, there is a process of supplying compressed air to both side air chambers at the same time.