Sensor and filter dryer

Abstract

A sensor for detecting a pressure difference of a fluid is disclosed, including: a housing having a first cavity, wherein the longitudinal axis of the first cavity defines a first end and a second end of the housing, and the first cavity communicates with the outside of the housing at the first end via a first fluid through hole and communicates with the outside of the housing at a position spaced apart from the first end via a second fluid through hole, and the housing is provided with an end element at the first end; a piston held inside the first cavity and can move between a first position and a second position along the longitudinal axis, wherein a flange is arranged on the circumferential outer side of the piston, and the flange is closer to the first end than the second fluid through hole; a spring positioned in the first cavity and can apply a force to the piston along the longitudinal axis, the sensor also has a piston position sensing assembly for sensing the relative position between the piston and the housing, and a circumferential gap through which fluid can flow is formed between the circumferential outer surface of the flange and the inner wall of the first cavity. The sensor has high sensitivity to fluid pressure difference. The invention also relates to a filter dryer.

Description

“SENSOR AND FILTER DRYER”TECHNICAL FIELD

[0001] The present invention relates to a sensor, in particular to a sensor for detecting pressure difference of a fluid and a filter dryer comprising the sensor.BACKGROUND

[0002] Differential pressure sensor is widely used in many industrial fields, and it detects the pressure difference of a fluid between different positions in a system. For example, a differential pressure sensor can be used to measure the pressure difference of a fluid between two points in a pipeline to monitor the fluid flow in the pipeline.

[0003] Some differential pressure sensors adopt two pressure sensors to measure the pressure at two points respectively, and then calculate the difference between the two pressure values. Some other differential pressure sensors directly make the fluid at two points act concurrently on a specific structure, such as a strain gauge, and acquire the difference of the pressure between the two points by detecting deformation or displacement related to the structure.

[0004] In some cases, such as in the fields of heating, ventilation and air conditioning, differential pressure sensors are also used to detect the clog level of a filter core of a filter dryer in the refrigerant passage. For this purpose, a differential pressure sensor is connected to the upstream and the downstream of the filter core respectively to detect the pressure of the refrigerant upstream and downstream of the filter core. For this kind of application scenarios, it is still hoped that the corresponding differential pressure sensor will have improved performance, such as higher sensitivity.SUMMARY

[0005] In view of the above problems, according to the first aspect of the invention, a sensor for detecting a pressure difference of a fluid is proposed, comprising:

[0006] a housing having a cylindrical first cavity, wherein a longitudinal axis of the first cavity defines a first end and a second end of the housing, the first cavity is in fluidcommunication with an outside of the housing at the first end via a first fluid through hole, and the first cavity is in fluid communication with the outside of the housing at a position spaced apart from the first end via a second fluid through hole, and the housing is provided with an end element at the first end;

[0007] a piston held inside the first cavity and movable along the longitudinal axis between a first position and a second position, wherein a flange is arranged on a circumferential outer side of the piston, and the flange is closer to the first end than the second fluid through hole;

[0008] a spring positioned in the first cavity and capable of applying a force along the longitudinal axis to the piston,

[0009] the sensor also has a piston position sensing assembly for sensing a relative position between the piston and the housing, wherein a circumferential gap is formed between a circumferential outer surface of the flange of the piston and an inner wall of the first cavity, and fluid can flow through the gap.

[0010] The sensor according to the first aspect of the present invention can detect the difference between the fluid pressure at the first fluid through hole and the fluid pressure at the second fluid through hole. Such detection has high accuracy and high sensitivity to the change in the pressure difference.

[0011] Specifically, in the sensor according to the present invention, the flange of the piston and the inner wall of the first cavity together define, in the first cavity, a first fluid space communicating with the first fluid through hole and a second fluid space communicating with the second fluid through hole. The fluid from the first fluid through hole and the fluid from the second fluid through hole first basically fill the first fluid space and the second fluid space, respectively, and respectively exert pressing forces on the piston in the first cavity in opposite directions. Said pressing forces push the piston until they are balanced with the other forces exerted on the piston, including the force generated by the deformation of the spring. Therefore, by detecting the position of the piston, the pressure difference between the first fluid through hole and the second fluid through hole can be obtained.

[0012] Further, in the sensor according to the present invention, a circumferential gapis provided between the circumferential outer surface of the flange on the piston and the inner wall of the first cavity, and the gap is configured such that fluid can flow through it. By setting this gap, the flange of the piston is not in contact with the inner wall of the first cavity, so the circumferential outer surface of the flange is subjected to little to no friction force. Therefore, even a small change in the pressure difference between the first fluid through hole and the second fluid through hole can also cause the piston to move and thus be detected. In fact, according to the inventor's analysis and calculation, even if a small amount of fluid flows from the first fluid space to the second fluid space through the gap due to the above pressure difference, the total pressure of this small amount of fluid hardly changes as the it travels through gap, so that the fluid pressure respectively subjected to by the two sides of the flange facing the first fluid space and the second fluid space does not change due to the existence of this flow. Therefore, the movement of the piston in the first cavity can accurately reflect a change of the pressure difference between the first fluid through hole and the second fluid through hole.

[0013] Due to the configuration and the working principle described above, the sensor according to the present invention has significantly improved sensitivity compared with the prior art differential pressure sensor. In some prior art differential pressure sensors, the periphery of the component (such as a piston) for separating two fluid spaces is provided with a dynamic seal. When the component moves due to the pressure difference between the two fluid spaces, the dynamic seal moves with it, and at the same time, the dynamic seal always abuts against the inner wall of the differential pressure sensor to seal and isolate the two fluid spaces. Therefore, the component in these prior art differential pressure sensors is always subjected to large friction, and it is difficult to respond sensitively to the change of pressure difference.

[0014] Meanwhile, the spring in the sensor according to the present invention can be set to a relatively long length to have a relatively low elastic coefficient. Therefore, the sensor according to the present invention can have improved sensitivity, thereby ultimately saving energy required for maintaining the operation of the system.

[0015] In addition, due to the configuration and the working principle described above, the sensor according to the present invention can be installed with any orientation, for example,with the first end of the sensor upward, with the first end of the sensor downward or with the sensor obliquely arranged, without affecting the normal operation and sensitivity of the sensor. Specifically, due to the configuration of the sensor, the weight of the piston is very small compared with the pressure difference between the two fluid spaces or the force exerted by the spring. Therefore, if the pressure difference between the two fluid spaces remains constant, the equilibrium position of the piston in the sensor does not vary according to the installation orientation of the sensor, so that the sensor has the ability of "anti-floating".

[0016] The sensor according to the present invention may have one or more of the following characteristics.

[0017] According to one embodiment, preferably, a minimum width of the gap along the circumferential direction does not exceed 0.25 mm. This embodiment is a preferred embodiment of the present invention, and the sensor according to this embodiment has improved detection sensitivity.

[0018] According to one embodiment, preferably, the flange is arranged at an end of the piston close to the first end, and the spring is arranged at a circumferential outer side of the piston, one end of the spring abuts against the flange, and the other end of the spring abuts against a step portion on the inner wall of the first cavity closer to the second end relative to the flange.

[0019] The spring in the sensor according to this embodiment can provide a stable pushing force on the piston toward the first end. In addition, the longitudinal length of the spring is allowed to be set longer, so that the difference between pressing forces acting on the piston can be converted into a greater deformation of the spring, and the sensitivity of the sensor can be further improved.

[0020] According to one embodiment, preferably, the first fluid through hole is provided passing through the end element, and the end element is configured such that when the piston is at the first position, the piston is in contact with the end element.

[0021] According to one embodiment, preferably, a side of the end element facing the first cavity is provided with an elastomer ring, and an end face of the piston facing the first end is provided with an annular protrusion, and when the piston is in the first position, the annularprotrusion is in sealing contact with the elastomer ring.

[0022] The sensor according to this embodiment is particularly advantageous in a case where the pressure difference between the first fluid through hole and the second fluid through hole is usually less than a specific value. When the pressure difference is less than a specific value, the piston is in the first position due to the pushing force of the spring, and at this time, the annular protrusion forms sealing contact with the elastomer ring, thereby preventing the fluid in the first fluid through hole from flowing toward the second fluid through hole.

[0023] For example, in a case where the first fluid through hole and the second fluid through hole of the sensor are respectively connected to the upstream and downstream of a filter in a fluid channel, the sensor according to this embodiment prevents the fluid entrained with dust particles from the upstream from directly flowing to the downstream of the filter without filtering when the filter clog level is low (that is, when the pressure difference between the upstream and the downstream is less than a specific value).

[0024] According to one embodiment, preferably, an area surrounded by an apex portion of the annular protrusion is at least 5% smaller than an area surrounded by a circumferential outermost edge of the flange.

[0025] The sensor according to this embodiment may be particularly advantageous when it is needed to detect a condition in which the pressure difference between the first fluid through hole and the second fluid through hole increases to a specific value. When the pressure difference does not reach the specified value, the piston is in the first position, and the annular protrusion forms a sealing contact with the elastomer ring, so that the fluid in communication with the first fluid through hole pushes the piston toward the second end only within an area surrounded by the apex portion of the annular protrusion. Once the pressure difference increases to the above-mentioned specific value, the fluid in communication with the first fluid through hole can flow to the circumferential outer side of the annular protrusion, pushing the piston toward the second end within the whole area surrounded by the outer periphery of the flange. Thereby, by adding an extra area on the circumferential outer side of the annular protrusion, when the pressure difference increases to the specific value, the piston and the elastomer ring are separated by a larger force.

[0026] According to another embodiment, preferably, an area surrounded by an apexportion of the annular protrusion is at most 15% smaller than an area surrounded by a circumferential outermost edge of the flange.

[0027] According to an embodiment, preferably, the piston position sensing assembly comprises a first magnet and a magnet position sensing assembly, wherein the first magnet is arranged at an end of the piston near the second end, and the magnet position sensing assembly is arranged at the second end of the housing.

[0028] The sensor according to this embodiment detects the position of the first magnet through the magnet position sensing assembly, thereby acquiring the position of the piston relative to the housing. Therefore, the fluid in the first cavity does not contact the magnet position sensing assembly, thus ensuring the normal operation of the magnet position sensing assembly.

[0029] According to one embodiment, preferably, the magnet position sensing assembly comprises a second magnet, an indicating component, and an elastic component, wherein the second magnet is connected to the indicating component, and a part of the elastic component is fixed relative to the housing, and the elastic component can apply a force away from the first end to the second magnet.

[0030] The sensor according to this embodiment can sense the position of the piston in a non-electrical way and will not be easily damaged, thus reducing the manufacturing cost.

[0031] According to one embodiment, preferably, the magnet position sensing assembly comprises a sensing assembly casing for accommodating the second magnet, the indicating component and the elastic component, and an observation window for observing the indicating component is arranged on the sensing assembly casing.

[0032] The sensor according to this embodiment can indirectly indicate the position of the piston in a non-electrical way, which is convenient for observation and reduces the manufacturing cost.

[0033] According to one embodiment, preferably, the magnet position sensing assembly comprises a Hall sensor.

[0034] The sensor according to this embodiment can output signals through the Hall sensor, so as to obtain an accurate position of the piston, which facilitates the subsequent implementation of corresponding measures.

[0035] According to one embodiment, preferably, the magnet position sensing assembly further comprises a processing element and a display element, wherein the processing element processes an electric signal output by the Hall sensor, so that the display element displays an associated processed signal.

[0036] The sensor according to this embodiment can directly display the signal output by the Hall sensor through the display element, which is convenient for judging the related pressure difference in the field.

[0037] According to one embodiment, preferably, the magnet position sensing assembly comprises a Reed switch.

[0038] The sensor according to this embodiment can output signals through the Reed switch, so as to obtain the position of the piston and thus the pressure difference. Such a sensor reduces the product cost at the same time.

[0039] According to one embodiment, preferably, the Reed switch is installed in a blind hole at the second end of the housing open away from the first cavity, and at least a part of the housing surrounding the blind hole is integrally formed.

[0040] The sensor according to this embodiment is less likely to have cracks generated in the housing, so it is impossible for the fluid in the first cavity to contact the magnet position sensing assembly, thus ensuring the safe operation of the magnet position sensing assembly.

[0041] According to one embodiment, preferably, the piston has a second cavity open toward the first end.

[0042] When the sensor according to this embodiment is in an installation orientation with the first end up and the second end down, smaller particles in the fluid from the first fluid through hole are collected by the second cavity that is open upward. Therefore, these smaller particles do not accumulate at other positions in the first cavity, thereby avoiding the piston or the spring stuck in the first cavity due to the accumulated smaller particles around them, so that the normal working time of the piston and the spring can be prolonged.

[0043] According to one embodiment, preferably, a first protruding portion is provided on the end element, and the first protruding portion protrudes toward the second end, the first fluid through hole penetrates through the first protruding portion, and the first protruding portion can at least partially be received in the second cavity.

[0044] The sensor according to this embodiment is further facilitates smaller particles in the fluid from the first fluid through hole to be retained in the second cavity, thus prolonging the normal working time of the piston and the spring.

[0045] According to an embodiment, preferably, the end element is a plunger, the plunger being sealingly connected to the housing body and comprising the first protruding portion.

[0046] The sensor according to this embodiment can be assembled and disassembled conveniently, and is convenient to manufacture and use.

[0047] According to one embodiment, preferably, the housing comprises a filter component arranged outside the housing at the first fluid through hole and / or the second fluid through hole.

[0048] For the sensor according this embodiment, larger particles in the fluid are blocked out of the housing with any orientation of the sensor, so that the normal working time of the piston and the spring can be prolonged.

[0049] According to the second aspect of the present invention, a filter dryer is proposed, which comprises a filter dryer housing and a sensor according to any one of the above embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to illustrate the technical solutions of the embodiments of the present disclosure more clearly, the accompanying drawings of the embodiments of the present disclosure will be briefly introduced hereinafter. The accompanying drawings are only used to illustrate some embodiments of the present disclosure, but not to limit all the embodiments of the present disclosure thereto.

[0051] Fig. l is a cross-sectional view of a sensor according to a first embodiment of the present invention, wherein the piston is in the first position.

[0052] Fig. 2 is a cross-sectional view of the sensor according to the first embodiment of the present invention, wherein the piston is in an intermediate position between the first position and the second position.

[0053] Fig. 3 is a cross-sectional view of the sensor according to the first embodimentof the present invention, wherein the piston is in the second position.

[0054] Fig. 4 is a partial cross-sectional view of the sensor according to the first embodiment of the present invention, wherein the piston is in the first position.

[0055] Fig. 5 is a partial cross-sectional view of the sensor according to the first embodiment of the present invention, wherein the piston is in the second position.

[0056] Fig. 6 is a cross-sectional view of a sensor according to a second embodiment of the present invention, wherein the magnet position sensing assembly includes a Hall sensor.

[0057] Fig. 7 is a cross-sectional view of a sensor according to a third embodiment of the present invention, wherein the magnet position sensing assembly includes a Reed switch.

[0058] Fig. 8A is a cross-sectional view of a sensor according to the third embodiment of the present invention installed on a filter dryer.

[0059] Fig. 8B is a perspective view of the sensor according to the third embodiment of the present invention installed on the filter dryer.

[0060] Fig. 9 is a cross-sectional view of a sensor according to the third embodiment of the present invention installed on a first valve component.

[0061] Fig. 10 is a cross-sectional view of a sensor according to the third embodiment of the present invention installed on a second valve component.

[0062] Fig. 11A is a schematic view of a sensor according to the second embodiment of the present invention installed on a differential pressure measuring assembly.

[0063] Fig. 11B is a cross-sectional view of the sensor according to the second embodiment of the present invention shown in Fig. 11 A fitted with an adapter.

[0064] Fig. 12 is a cross-sectional view of a sensor according to the third embodiment of the present invention for measuring the liquid level in a pipeline.

[0065] List of reference numerals1 sensor100 housing101 first end of the housing102 second end of the housing105 first cavity106 inner wall of the first cavity110 first fluid through hole115 first filter component120 second fluid through hole125 second filter component130 step portion140 elastomer ring150 blind hole180 housing body182 sealing ring190 end element, plunger195 first protruding portion200 piston210 flange211 circumferential outer surface of the flange212 circumferential outermost edge of the flange220 gap230 annular protrusion231 apex portion of the annular protrusion240 second cavity300 spring310 first fluid through hole320 second fluid through hole382 sealing ring400 piston position sensing assembly410 first magnet420 magnet position sensing assembly421 second magnet422 indicating component423 elastic component425 sensing assembly casing426 observation window430 magnet position sensing assembly431 Hall sensor440 magnet position sensing assembly441 Reed switch500 filter dryer510 housing of the filter dryer511 inlet of the filter dryer512 outlet of the filter dryer513 cavity of the filter dryer515 housing body of the filter dryer520 cover of the filter dryer521 first sensor receiving portion of the cover of the filter dryer522 through hole of the cover of the filter dryer for the supporting rod525 maintenance hole of the cover of the filter dryer526 second sensor receiving portion of the cover of the filter dryer530 filter core540 holding frame of the filter core545 supporting rod of the holding frame of the filter core546 inner cavity of the supporting rod547 first end of the supporting rod548 second end of the supporting rod550 screw600 first valve assembly610 upstream of the filter screen620 downstream of the filter screen625 downstream channel630 filter screen700 second valve assembly710 upstream of the filter screen720 downstream of the filter screen725 downstream channel730 filter screen800 pressure difference measuring assembly850 adapter851 inlet of the adapter852 outlet of the adapter900 pipeline910 bottom of the pipeline920 liquid level in the pipeline930 measuring tube in the pipelineL longitudinal axisDETAILED DESCRIPTION OF THE EMBODIMENTS

[0066] In order to make the purpose, technical solution and advantages of the technical solutions of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings of specific embodiments of the present disclosure. In the drawings, the same reference numerals represent the same parts. It should be noted that the described embodiments are part of the embodiments of the present disclosure, but not all of them. Based on the described embodiments of the present disclosure, all other embodiments obtained by those of skills in the art without creative labor are within the protection scope of the present disclosure.

[0067] Unless otherwise defined, the technical terms or scientific terms used here shall have their ordinary meanings as understood by those with ordinary skills in the field to which this invention belongs. The words "first", "second" and the like used in the description andclaims of the patent application of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words "a" or "an" and the like do not necessarily mean quantity limitation. Words "comprising" or "including" and the like mean that the elements or objects appearing before the word cover the listed elements or objects appearing after the word and their equivalents, without excluding other elements or objects. Phrases like "connected to" or "connected with" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left" and "right" are only used to express relative positional relationship. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0068] The present disclosure will be described in detail below by describing example embodiments.

[0069] Figs. 1 to 3 show a cross-sectional view of a sensor 1 for detecting a pressure difference of a fluid according to a first embodiment of the present invention. Figs. 4 and 5 show a partially enlarged cross-sectional view of the sensor 1 according to the first embodiment of the present invention. As shown in Fig. 1, the sensor 1 includes a housing 100, a piston 200, a spring 300 and a piston position sensing assembly 400.

[0070] As shown in Figs. 1 to 3, the housing 100 includes a housing body 180 and a plunger 190. The plunger 190 is hermetically connected to a housing opening 181 of the housing body 180. For example, the plunger 190 and the housing opening 181 are sealed by an elastomer ring 140. The plunger 190 and the housing body 180 together define a first cavity 105 inside the housing body 180. The first cavity 105 has a cylindrical shape, thereby defining a longitudinal axis L. In other words, the first cavity 105 extends along the longitudinal axis L. The housing 100 defines a first end 101 and a second end 102 of the housing 100 with respect to the longitudinal axis L. The plunger 190 is located at the first end 101 of the housing 100.

[0071] The plunger 190 is provided with a first fluid through hole 110 penetrating through the plunger 190, and the first cavity 105 is in fluid communication with the outside of the housing 100 through the first fluid through hole 110. The housing body 180 is provided with a second fluid through hole 120 at a position spaced part from the first end 101 of the housing 100, for example, at the lateral side of the housing body 180. The first cavity 105 isalso in fluid communication with the outside of the housing 100 through this second fluid through hole 120. In addition, as shown in Figs. 1 to 3, a filter member 115, such as a filter screen 115, is provided at the first fluid through hole 110 outside the housing 100 to prevent larger particles (such as dust particles) from entering the first cavity 105 through the first fluid through hole 110. A filter member 125, such as a filter screen 125, is provided at the second fluid through hole 120 outside the housing 100 to prevent larger particles from entering the first cavity 105 through the second fluid through hole 120. As a result, larger particles are prevented from staying in the first cavity 105 and hindering the deformation of the spring 300 and the movement of the piston 200.

[0072] In addition, the housing 100 also includes a sealing component suitable for mounting to related equipment or components. For example, a sealing ring 182 is provided on the outer periphery of the housing body 180. The housing body 180 may also be provided with a boss or the like for form-fitting installation to related equipment or components.

[0073] With further reference to Figs. 1 to 3, the piston 200 is arranged inside the first cavity 105 and can move inside the first cavity 105 along the longitudinal axis L. The piston 200 is of a cylindrical shape and has a flange 210 at an end near the first end 101. Referring to Fig. 4, there is a gap 220 between the circumferential outer surface 211 of the flange 210 and the inner wall 106 of the first cavity 105. The gap 220 is configured such that there is no direct contact between the circumferential outer surface 211 of the flange 210 and the inner wall 106, and when there is a pressure difference between the two ends of the gap 220 with respect to the longitudinal axis L, the fluid from the first fluid through hole 110 can flow through the gap 220. Further, the width of the gap 220 is narrow, and the width is set to be small relative to the length dimension of the first cavity 105, e.g., the radius of the first cavity 105, so that the flow of fluid through the gap 220 does not cause the fluid pressure on both sides of the flange 210 with respect to the longitudinal axis L to change. For example, the minimum width of the gap along the circumferential direction does not exceed 0.25 mm. That is to say, the minimum value of the width of the gap along the circumferential direction does not exceed 0.25 mm.

[0074] As a result, the piston 200 with the flange 210 actually divides the first cavity 105 roughly into a first fluid space in fluid communication with the first fluid through hole 110 and a second fluid space in fluid communication with the second fluid through hole 120. Thefirst fluid space and the second fluid space are in fluid communication only through the narrow gap 220. The fluid in the first fluid space generally exerts a pressing force on the piston 200 toward the second end 102, and the fluid in the second fluid space generally exerts a pressing force on the piston 200 toward the first end 101.

[0075] In addition, in Figs. 1 to 3, a spring 300 is also shown. One end of the spring 300 abuts against a side of the flange 210 of the piston 200 facing the second end 102, and the other end of it abuts against a step portion 130 on the inner wall 106 of the first cavity 105. Thereby, the spring 300 applies opposite pushing forces between the piston 200 and the housing 100 along the longitudinal direction L, wherein the spring 300 applies a pushing force to the piston 200 toward the first end 101.

[0076] In the sensor 1 according to the first embodiment of the present invention, a second cavity 240 is provided inside the piston 200. The second cavity 240 is open to the first end 101. As a result, in a case where the sensor is in an installation orientation with the first end 101 upward and the second end 102 downward, the second cavity 240 is open upward, and smaller particles entrained in the fluid from the first fluid through hole 110 can be deposited in the second cavity 240. Therefore, smaller particles are prevented from staying in other positions of the first cavity 105 and hindering the deformation of the spring 300 and the movement of the piston 200. Figs. 1 to 3 also show a first protruding portion 195 on the plunger 190. The first protruding portion 195 can be at least partially received in the second cavity 240, thereby guiding the fluid from the first fluid through hole 110 to move in the second cavity 240 toward the direction second end 102, so that smaller particles entrained in the fluid are more easily deposited in the second cavity 240.

[0077] In the sensor 1 according to the first embodiment of the present invention, an end face of the piston 200 facing the first end 101 is provided with an annular protrusion 230. When the piston 200 abuts against an end face of the first cavity 105 near the first end 101, the annular protrusion 230 comes into sealing contact with the elastomer ring 140 exposed toward the second end 102. The specific effect of this setting will be described in detail later.

[0078] Figs. 1 to 3 also show a first magnet 410 fixedly arranged at an end of the piston 200 near the second end 102. The first magnet 410 is a part of the piston position sensing assembly 400. The piston position sensing assembly 400 further includes a magnet positionsensing assembly 420 disposed at the second end 102 of the housing 100 for detecting the position of the first magnet 410, thereby acquiring the position of the piston 200 relative to the housing 100.

[0079] In the first embodiment shown in Figs. 1 to 3, the magnet position sensing assembly 420 detects the position of the first magnet 410 in a non-electrical way. The magnet position sensing assembly 420 includes a second magnet 421, an indicating component 422 and an elastic component 423.

[0080] The elastic component 423 is a coil spring, one end of which is fixed to the outside of the housing 100 at the second end 102, for example, in a blind hole 150, and the other end of which is connected to the indicating component 422. The indicating component 422 has a rod-shaped body, the middle section of which is connected with the other end of the coil spring 423. The second magnet 421 is fixedly arranged at one end of the rod-shaped body close to the housing 100, and a display portion is arranged at one end of the rod-shaped body away from the housing 100. The display portion has a bright color or a reflective surface, for example, so that relevant personnel can observe its position conveniently.

[0081] In the magnet position sensing assembly 420, the second magnet 421 can be subjected to the force from the first magnet 410 along the longitudinal axis L. When the position of the first magnet 410 changes along the longitudinal direction L with the movement of piston 200, the interaction force between the first magnet 410 and the second magnet 421 changes, causing the movement of the second magnet 421, which in turn causes the movement of the corresponding indicating component 422 and the further deformation of the coil spring 423, until all the forces in the system reach a new balance. Therefore, by observing the position of the display portion of the indicating component 422, the position of the piston 200 relative to the housing 100 can be obtained.

[0082] In the first embodiment, the magnet position sensing assembly 420 further includes a sensing assembly casing 425, which accommodates the second magnet 421, the indicating component 422 and the elastic component 423. The sensing assembly casing 425 is provided with an observation window for observing the indicating component 422. Therefore, the second magnet 421, the indicating component 422 and the elastic component 423 can be protected by the sensing assembly casing 425 without obstructing the observation of theposition of the indicating component 422.

[0083] Next, with continued reference to Figs. 1 to 3, the way in which the sensor 1 senses the fluid pressure difference between the first fluid through hole 110 and the second fluid through hole 120 will be described.

[0084] According to the above, the fluid in the first fluid space has a first fluid pressure, which generally applies a pressing force to the piston 200 toward the second end 102, hereinafter referred to as the first fluid pressing force. The fluid in the second fluid space has a second fluid pressure, which generally applies pressing force to the piston 200 toward the first end 101, hereinafter referred to as the second fluid pressing force, and the spring 300 can apply a pressing force to the piston 200 toward the first end 101. When the relationship between the first fluid pressure and the second fluid pressure varies, the position of the piston 200 is caused to change, as described below.

[0085] When the first fluid pressure is less than the second fluid pressure, or when the first fluid pressure is greater than the second fluid pressure and the pressure difference obtained through subtracting the first fluid pressure by the second fluid pressure is less than a first threshold, the sum of the second fluid pressing force and the pressing force exerted by the spring 300 on the piston 200 are greater than the first fluid pressing force. At this time, the piston 200 is made to abut against the end face of the first cavity 105 near the first end 101, that is, the piston 200 is made to abut against the side of the plunger 190 facing the first cavity 105. That is to say, the piston 200 in the first position, as shown in Fig. 1.

[0086] When the pressure difference obtained through subtracting the first fluid pressure by the second fluid pressure is equal to the above-mentioned first threshold, the sum of the second fluid pressing force and the pressing force exerted by the spring 300 on the piston 200 are equal to the first fluid pressing force. At this time, the piston 200 is still in the first position, but its end near the first end 101 (i.e., its end near the plunger 190) is no longer supported by the plunger 190.

[0087] When the pressure difference obtained through subtracting the first fluid pressure by the second fluid pressure increases to be greater than the above-mentioned first threshold, the first fluid pressing force increases to be greater than the sum of the second fluid pressing force and the pressing force exerted by the spring 300 on the piston 200. At this time,the first fluid pressing force starts to push the piston 200 to move toward the second end 102, which further causes the flange 210 of the piston 200 to further press the spring 300, which in turn causes the pressing force exerted by the spring 300 on the piston 200 to increase. As a result, the piston 200 moves until the pressing forces acting on it reach a new balance, as shown in Fig. 2.

[0088] When the pressure difference obtained through subtracting the first fluid pressure by the second fluid pressure further increases to a second threshold, which is greater than the first threshold, the piston 200 moves to a second position where the piston 200 abuts against the end of the first cavity 105 opposite to the plunger 190, i.e., the end face of the piston 200 near the second end 102 abuts against the end face of the first cavity near the second end, as shown in Fig. 3.

[0089] Therefore, the change of the pressure difference between the first fluid pressure and the second fluid pressure within a certain range can be reflected by the position of the piston 200 relative to the housing 100, which can be obtained, for example, through the piston position sensing assembly 400 described above. When the piston 200 is in the first position, as shown in Fig. 1, the second magnet 421 of the piston position sensing assembly 400 is far away from the piston 200 along the longitudinal axis L, and the indicating component 422 is far away from the piston 200 and close to the observation window 426. When the piston 200 is in an intermediate position between the first position and the second position, as shown in Fig. 2, the second magnet 421 moves closer to the piston 200, and the indicating component 422 is away from the observation window 426 for a certain distance. When the piston 200 reaches the second position, as shown in Fig. 3, the second magnet 421 is even closer to the piston 200, and the indicating component 422 is further away from the observation window 426.

[0090] In the sensor 1 according to the present invention, there is a gap between the flange 210 and the inner wall 106 of the first cavity 105, and there is no friction between the flange 210 and the inner wall 106 of the first cavity 105. Therefore, the sensor 1 has high detection accuracy for the pressure difference and high detection sensitivity for the change of the pressure difference.

[0091] Figs. 4 and 5 show a partial cross-sectional view near the plunger 190 of the sensor 1, which show the state when the piston 200 is in the first position and the secondposition, respectively. As mentioned above, when the piston 200 is in the first position (Fig. 4), the apex portion 231 of the annular protrusion 230 of the piston 200 can form sealing contact with the elastomer ring 140, thus blocking the fluid communication between the first fluid through hole 110 and the second fluid through hole 120.

[0092] This arrangement is particularly advantageous when the sensor 1 is used to measure the fluid pressure difference between the upstream and downstream of a filter screen or a filter core. In this kind of application, the fluid pressure difference between the upstream and downstream of a filter such as a filter screen or a filter core may gradually increase due to the pollution and clog of the filter, and the sensor 1 can detect the clog level of the filter by measuring the fluid pressure difference. By setting the sensor 1 to block the fluid communication between the first fluid through hole 110 and the second fluid through hole 120 at the first position of the piston 200, it is possible to prevent the upstream fluid with contaminating particles from flowing directly to the downstream (i.e., from the first fluid through hole 110 to the second fluid through hole 120 via the gap 220) without being filtered when the filter is working normally.

[0093] In addition, according to the first embodiment of the present invention, the area surrounded by the apex portion 231 of the annular protrusion 230 can be at least 5% smaller than the area surrounded by the circumferential outermost edge 212 of the flange, which further improves the sensitivity of the sensor 1 when the pressure difference reaches the first threshold. Specifically, when the pressure difference has not reached the first threshold, the apex portion 231 forms sealing contact with the elastomer ring 140. Therefore, the piston 220 is subjected to pressure difference between the fluid from the first fluid through hole 110 and the fluid from the second fluid through hole 120 only in the area surrounded by the apex portion 231. Once the pressure difference increases to slightly greater than the first threshold, the apex portion 231 separates from the elastomer ring 140 with a gradually increasing distance. At this time, the piston 220 is subjected to pressure difference between the fluid from the first fluid through hole 110 and the fluid from the second fluid through hole 120 in the area surrounded by the circumferential outermost edge 212 of the flange. In other words, once the pressure difference increases to be slightly greater than the first threshold, the force that pushes the piston 200 to move toward the second end 102 will increase significantly, so that the sensor 1 can output anobservable signal.

[0094] Therefore, when the sensor 1 is used to measure the fluid pressure difference between the upstream and downstream of the filter screen or filter core, it can sensitively detect a condition in which the filter is at an intermediate clog level, which is convenient for users to know the working condition of the filter and take corresponding measures in time according to requirements.

[0095] Fig. 6 shows a sensor 2 according to a second embodiment of the present invention. Other configurations of the sensor 2 are the same as those of the sensor 1, except that the sensor 2 adopts a magnet position detection device 430 in an electrical form. Specifically, the magnet position detection device 430 includes a Hall sensor 431 fixedly arranged in a blind hole 150. The Hall sensor 431 can detect the relative position of the first magnet 410 and output corresponding electrical signals for subsequent processing.

[0096] The magnet position detection device 430 may further include a display element and a processing element (not shown). The processing element processes the electrical signal output by the Hall sensor 431, so that the display element displays the associated processed signal. For example, the Hall sensor 431 outputs a voltage signal which is related to the relative position of the first magnet 410. The processing element judges which voltage range, among a series of voltage ranges, the voltage signal belongs to. In addition, the display element can be, for example, a plurality of LED lamps, and each LED lamp corresponds to a corresponding voltage range. The processing element further lights the corresponding LED lamps according to the voltage range to which voltage signal belongs, in order to remind the corresponding state of the pressure difference.

[0097] Fig. 7 shows a sensor 3 according to a second embodiment of the present invention. Other configurations of the sensor 3 are the same as those of the sensor 1, except that the sensor 3 adopts a magnet position detection device 440 in an electrical form. Specifically, the magnet position detection device 440 includes a Reed switch 441 fixedly arranged in the blind hole 150. The Reed switch 441 can detect the relative position of the first magnet 410 and output corresponding electrical signals for subsequent processing.

[0098] In the sensors 1, 2, 3 according to the present invention, the housing body 180 may be integrally formed. In particular, for the sensors 2 and 3, at least the part of the housing100 surrounding the blind hole 150 may be integrally formed. Such a provision can reduce the possibility that the housing 100 is cracked near the blind hole 150, thus preventing the fluid in the system from entering the blind hole and damaging the magnet position detection device. For sensors applied to the refrigerant system, such a provision can especially reduce the possibility of igniting the refrigerant, thus improving the safety of the refrigerant system.

[0099] Figs. 8A and 8B show a filter dryer 500 according to the present invention, which includes a sensor 3 according to the present invention for measuring the pressure difference before and after the fluid flows through the filter core 530 of the filter dryer 500. Alternatively, the filter dryer 500 may also include the sensor 1 or the sensor 2 according to the present invention.

[0100] As shown in Fig. 8A, the filter dryer 500 has a filter dryer housing 510 and a filter core 530. The filter dryer housing 510 has a cavity 513 therein, and the cavity 513 is in fluid communication with the outside of the filter dryer 500 via an inlet 511 and an outlet 512. The filter core 530 has a hollow cylindrical shape and is arranged in the cavity 513. Specifically, the filter core 530 is held in a holding frame 540, and the holding frame 540 is fixed in the cavity 513.

[0101] When the filter dryer 500 is used to filter and dry the fluid, the fluid to be filtered and dried enters the cavity 513 through the inlet 511 of the filter dryer, then passes through the material of the filter core 530 from the circumferential outside of the filter core 530 into the hollow interior of the filter core 530, and then flows to the outlet 512 through a through hole of the holding frame 540 near the outlet 512, thereby leaving the filter dryer 500 from the outlet 512. The structure of the holding frame 540 is such that the fluid in the hollow interior of the filter core 530 can only leave the filter core 530 from the side of the holding frame 540 close to the outlet 512, e.g., from the through hole, but cannot leave the filter core 530 from the other side opposite to said side, thus facilitating the installation and operation of the sensor 3, as described in detail below.

[0102] The filter dryer housing 510 includes a housing body 515 of the filter dryer and a cover 520 disposed at a side away from the outlet 512. The cover 520 can be sealingly fixed to the housing body 515, for example, by screws 550. The sensor 3 is mounted on the cover 520. Specifically, the cover 520 is provided with a first sensor receiving portion 521, which isa through hole passing through the cover 520. As shown in Fig. 8A, a part of the sensor 3 passes through the first sensor receiving portion 521, and the first fluid through hole 310 and the first filter component of the sensor 3 are exposed to a measuring space 514 inside the filter dryer housing 510. The measuring space 514 is in fluid communication with the fluid space at the inlet 511 of the filter dryer housing 510, and the filter dryer housing 510 is configured such that the fluid pressure at the first fluid through hole 310 of the sensor 3 approximately equal to the fluid pressure at the measuring inlet 511. Therefore, the pressure near the inlet 511 of the filter dryer 500 can be sensed by the sensor 3 via the first fluid through hole of the sensor 3.

[0103] In addition, a supporting rod 545 is disposed at the axial center line of the substantially cylindrical holding frame 540. In use, the supporting rod 545 can be fixed to the holding frame 540 to hold the filter core 530 in the holding frame 540. Both ends of the supporting rod 545, namely the first end 547 and the second end 548, extend to the outside of the holding frame 540 to facilitate the aforementioned fixing function and the installation process. Furthermore, according to an embodiment of the present invention, the supporting rod 545 is hollow and tubular, that is, it has an inner cavity 546, and the supporting rod 545 is open at both ends 547 and 548. Therefore, the fluid near the first end 547 of the supporting rod 545 is in communication and have approximately the same pressure with the fluid near the second end 548.

[0104] According to Fig. 8A, the first end 547 of the supporting rod 545 is placed in a through hole 522 provided in the cover 520, so that the fluid in the first end 547 of the supporting rod 545 can enter the interior of the sensor 3 via the second fluid through hole 320 of the sensor 3. The second end 548 of the supporting rod 545 is located near the outlet 512 of the filter dryer 500. Therefore, the pressure near the outlet 512 of the filter dryer 500 can be sensed by the sensor 3 via the second fluid through hole 320 of the sensor 3.

[0105] As a result, the sensor 3 included in the filter dryer 500 as shown in Figs. 8A and 8B can detect the pressure difference between the inlet 511 and the outlet 512 of the filter dryer 500, and further detect the clog level of the filter core 530 therein.

[0106] Specifically, when the filter dryer 500 operates, the pressure at the inlet 511 is generally greater than the pressure at the outlet 512. When the filter core 530 is not clogged, or the clog level is low, the pressure difference between the inlet 511 and the outlet 512 is small,so the pressure difference between the first fluid through hole and the second fluid through hole of the sensor 3 is small, and the piston of the sensor 3 is in the first position, that is, the piston of the sensor 3 abuts against the plunger of the sensor 3 (see description above). When the filter core 530 is clogged to a certain extent, and the pressure difference between the inlet 511 and the outlet 512 increases to a certain extent, so that the pressure difference between the first fluid through hole and the second fluid through hole of the sensor 3 increases to the first threshold, and the piston of the sensor 3 is no longer abutting against the plunger of the sensor 3. When the clog level of the filter core 530 is further increased slightly, the piston moves to an intermediate position between the first position and the second position. Next, as the clog level of the filter core 530 continues to increase, the pressure difference between the inlet 511 and the outlet 512 further increases, and the piston finally moves to the position which is far away from the first fluid through hole and in which the piston abuts against the inner wall of the first cavity of the sensor 3 (i.e. the end of the first cavity of the sensor 3 opposite to the plunger). In this process, the piston position sensing assembly of the sensor 3 senses the relative position of the piston and gives a corresponding signal to indicate the clog level of the filter core 530.

[0107] It should be noted that the filter dryer 500 according to the present invention has a simple process of assembling various components. For example, first, the filter core 530, the holding frame 540 and the supporting rod 545 are assembled as a filter core assembly outside of the filter dryer housing 510, and then the filter core assembly is placed into the housing body 515. Next, the cover 520 on which the sensor 3 is mounted is fixed to the housing body 515 along the axial direction of the filter core 530, so that the first end 547 of the supporting rod 545 is placed in the through hole 522. In such an assembly process, there is no need for an additional step of connecting each fluid inlet of the sensor to a corresponding position in the fluid path of the system. In addition, the filter dryer 500 according to the present invention can be provided with a maintenance hole 525 and a second sensor receiving portion 526 for other sensors on the cover 520, which is convenient for observing the state of each part of the filter dryer 500 and for maintenance.

[0108] Fig. 9 shows a schematic view of the sensor 3 according to the present invention as part of a valve assembly 600. The sensor 3 is mounted near a filter screen 630 to detect the clog level of the filter screen 630. The first fluid through hole 310 of the sensor 3 is in fluidcommunication with the upstream 610 of the filter screen 630 of the valve assembly, and the second fluid through hole 320 of the sensor 3 is in fluid communication with the downstream 620 of the filter screen 630 via a downstream channel 625.

[0109] Similar to the case of the aforementioned filter dryer 500, generally, the fluid pressure in the upstream 610 of the filter screen 630 is greater than that in the downstream 620. As the clog level of the filter screen 630 increases, the pressure difference between the upstream 610 and the downstream 620 increases, so that the pressure difference between the first fluid through hole 310 and the second fluid through hole 320 of the sensor 3 increases. As a result, the piston in the sensor 3 moves, which is sensed by the piston position sensing assembly, and the piston position sensing assembly outputs relevant signals.

[0110] Fig. 10 shows a schematic view of the sensor 3 according to the present invention as a part of another valve assembly 700. The sensor 3 is mounted near the filter screen 730 to detect the clog level of the filter screen 730. The first fluid through hole 310 of the sensor 3 is in fluid communication with the upstream 710 of the filter screen 730 of the valve assembly, and the second fluid through hole 320 of the sensor 3 is in fluid communication with the downstream 720 of the filter screen 730 via a downstream channel 725.

[0111] Similar to the case of the aforementioned valve assembly 600, generally, the fluid pressure in the upstream 710 of the filter screen 730 is greater than that in the downstream 720. As the clog level of the filter screen 730 increases, the pressure difference between the upstream 710 and the downstream 720 increases, so that the pressure difference between the first fluid through hole 310 and the second fluid through hole 320 of the sensor 3 increases. As a result, the piston in the sensor 3 moves, which is sensed by the piston position sensing assembly, and the piston position sensing assembly outputs relevant signals.

[0112] Fig. 11A shows a schematic view of the sensor 3 according to the present invention as a part of a differential pressure sensor assembly 800, and Fig. 11B shows the sensor 3 and an adapter 850 for mounting the sensor 3 to the body of the differential pressure sensor assembly 800. Two different pressure sources can be connected to an inlet 851 and an outlet 852 of the adapter 850 respectively. The inlet 851 of the adapter 850 is connected to the first fluid through hole 310 of the sensor 3, and the outlet 852 is connected to the second fluid through hole 320 of the sensor 3. This arrangement can further simplify the installation of thesensor 3 on various differential pressure sensor assemblies.

[0113] Fig. 12 shows a schematic view of the sensor 3 according to the present invention used in a differential pressure switch in a U-shaped pipeline 900, and the sensor 3 can function as a float switch.

[0114] As shown in Fig. 12, the sensor 3 is mounted on a measuring tube 930 extending upward from the bottom 910 of the pipeline. The first fluid through hole 310 of the sensor 3 is in fluid communication with the bottom 910 of the pipeline, and the second fluid through hole 320 is in communication with the atmospheric pressure. A sealing ring 382 is provided on the sensor 3 between the first fluid through hole 310 and the second fluid through hole 320 of the sensor 3. The sealing ring 382 seals the outer periphery of the sensor 3 with the inner wall of the measuring tube 930, so as to prevent liquid from leaking from the pipeline 900 to the outside.

[0115] When the liquid level 920 in the pipeline rises or falls, the pressure at various positions in the liquid changes. The sensor 3 detects the difference between the liquid pressure where the first fluid through hole 310 is located and the atmospheric pressure, and then obtains the liquid level of the liquid in the pipeline. Therefore, the sensor 3 can sensitively detect the safety of the pipeline.

[0116] Exemplary implementations of the sensor and the filter dryer proposed by the present invention are described in detail above with reference to the preferred embodiments. However, those skilled in the art can understand that, without departing from the concept of the present invention, various changes and modifications on the above-mentioned specific embodiments can be made, and various technical features and structures proposed in the present invention can be combined in various ways without exceeding the protection scope of the present invention.

Claims

CLAIMS:

1. A sensor (1) for detecting a pressure difference of a fluid, comprising: a housing (100) having a cylindrical first cavity (105), wherein a longitudinal axis (L) of the first cavity defines a first end (101) and a second end (102) of the housing, the first cavity is in fluid communication with an outside of the housing at the first end via a first fluid through hole (110), and the first cavity is in fluid communication with the outside of the housing at a position spaced apart from the first end via a second fluid through hole (120), and the housing (100) is provided with an end element (190) at the first end (101); a piston (200) held inside the first cavity and movable along the longitudinal axis between a first position and a second position, wherein a flange (210) is arranged on a circumferential outer side of the piston, and the flange (210) is closer to the first end (101) than the second fluid through hole (120); a spring (300) positioned in the first cavity and capable of applying a force along the longitudinal axis to the piston, the sensor (1) also has a piston position sensing assembly (400) for sensing a relative position between the piston and the housing, wherein a circumferential gap (220) is formed between a circumferential outer surface (211) of the flange (210) of the piston (200) and an inner wall (106) of the first cavity (105), and fluid can flow through the gap (200).

2. The sensor according to claim 1, wherein a minimum width of the gap (220) along the circumferential direction does not exceed 0.25 mm.

3. The sensor according to claim 1, wherein the flange (210) is arranged at an end of the piston (200) close to the first end (101), and the spring (300) is arranged at a circumferential outer side of the piston (200), one end of the spring abuts against the flange, and the other end of the spring abuts against a step portion (130) on the inner wall of the first cavity closer to the second end relative to the flange.

4. The sensor according to claim 1, wherein the first fluid through hole (110) is provided passing through the end element (190), and the end element (190) is configured such that when the piston (200) is at the first position, the piston (200) is in contact with the end element (190).

5. The sensor according to claim 4, wherein a side of the end element (190) facing the first cavity (105) is provided with an elastomer ring (140), and an end face of the piston (200) facing the first end is provided with an annular protrusion (230), and when the piston is in the first position, the annular protrusion (230) is in sealing contact with the elastomer ring (140).

6. The sensor according to claim 5, wherein an area surrounded by an apex portion (231) of the annular protrusion (230) is at least 5% smaller than an area surrounded by a circumferential outermost edge (212) of the flange.

7. The sensor according to claim 6, wherein the piston (200) has a second cavity (240) open toward the first end (101).

8. The sensor according to claim 7, wherein a first protruding portion (195) is provided on the end element (190), and the first protruding portion protrudes toward the second end (102), the first fluid through hole (110) penetrates through the first protruding portion (195), and the first protruding portion can at least partially be received in the second cavity (240).

9. The sensor according to claim 8, wherein the end element (190) is a plunger (190), the plunger (190) being sealingly connected to the housing body (180) and comprising the first protruding portion (195).

10. The sensor according to any one of claims 1 to 9, wherein the piston position sensing assembly (400) comprises a first magnet (410) and a magnet position sensing assembly (420, 430, 440), wherein the first magnet is arranged at an end of the piston (200) near the second end, and the magnet position sensing assembly is arranged at the second end of the housing.

11. The sensor according to claim 10, wherein the magnet position sensing assembly (420) comprises a second magnet (421), an indicating component (422), and an elastic component (423), wherein the second magnet is connected to the indicating component, and a part of the elastic component is fixed relative to the housing, and the elastic component can apply a force away from the first end to the second magnet.

12. The sensor according to claim 11, wherein the magnet position sensing assembly (420) comprises a sensing assembly casing (425) for accommodating the second magnet, the indicating component and the elastic component, and an observation window (426) for observing the indicating component is arranged on the sensing assembly casing.

13. The sensor according to claim 10, wherein the magnet position sensing assembly (430) comprises a Hall sensor (431).

14. The sensor according to claim 13, wherein the magnet position sensing assembly (430) further comprises a processing element and a display element, wherein the processing element processes an electric signal output by the Hall sensor, so that the display element displays an associated processed signal.

15. The sensor according to claim 10, wherein the magnet position sensing assembly (440) comprises a Reed switch (441).

16. The sensor according to claim 15, wherein the Reed switch (441) is installed in a blind hole (150) at the second end of the housing (100) open away from the first cavity, and at least a part of the housing (100) surrounding the blind hole (150) is integrally formed.

17. The sensor according to claim 1, wherein the housing (100) comprises a filter component (115, 125) arranged outside the housing at the first fluid through hole (110) and / or the second fluid through hole (120).

18. A filter dryer (500) compri sing a filter dryer housing (510) and the sensor ( 1 ) according to any one of claims 1 to 17.

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