A dispensing valve with a reflux structure

Abstract

A dispensing valve with a reflux structure provided by the present invention includes a dispensing valve body, a dispensing valve piston and a dispensing valve stem. A power chamber, a movable chamber, a glue inlet chamber, a control chamber and a slide bar chamber are sequentially arranged inside the dispensing valve body. In the dispensing valve with a reflux structure provided by the present invention, a glue suction structure is formed by the cooperation of the dispensing valve stem, the glue inlet chamber and the control chamber inside the device. The dispensing valve stem moves up and down to change the volume of the inner cavities of the glue inlet chamber and the control chamber to form negative pressure, so as to well suck the residual glue inside the dispensing tube back into the dispensing valve body at the moment when the dispensing machine stops dispensing, which well avoids the phenomena of dripping glue or wire drawing.

Description

Technical Field

[0001] The present invention relates to the technical field of dispensing equipment, and particularly to a dispensing valve with a reflux structure. Background Art

[0002] The dispensing valve is the most important working component on the dispenser. A dispenser is an automated machine that controls fluids through a dispensing valve and drips or coats the fluids on the surface or inside of products. With the continuous development of technology, dispensers are widely used in the automotive manufacturing industry, electronic manufacturing industry, industrial electricity, solar photovoltaics, construction engineering, etc., and the market application is quite popular; currently, the equipment is manual, semi-automatic, and fully automatic. The degree of automation is getting higher and higher.

[0003] The application fields of dispensers are constantly enriched and developed, and various forms of requirements are also put forward for the dispensing valve. Currently, there are more than 30 types of existing dispensing valve models in the dispensing industry market. According to the dispensing method, the dispensing valve can be divided into contact type and non-contact type. The non-contact dispensing valve is a new technology developed in recent years. Similar to the inkjet printing principle, it has the advantages of fast speed and small glue dots, but the technology is not yet very mature and is very sensitive to the viscosity of the glue; while the traditional contact dispensing valve is widely used because of its simple and reliable structure, stable performance, wide application range, and long service life. Common ones include: thimble type dispensing valve, plunger type dispensing valve, diaphragm type dispensing valve, AB dual-liquid dispensing valve, and rotary dispensing valve, etc.

[0004] Common problems when the existing dispensing valve is dispensing are the glue remaining on the needle tip after dispensing and the problem of wire drawing during dispensing. The glue remaining on the needle tip, part of it will drip onto the product or fixture due to gravity, and part of it will cause a reduction in the glue output due to solidification, affecting the product quality and even clogging the needle tip or needle tube; wire drawing occurs when the needle tip moves. If the wire drawing gets on the adhesive, it will affect the dispensing effect. At the same time, when the glue inside the dispensing valve cannot be used up in time, the glue will solidify, thus affecting the overall working efficiency of the dispenser. Summary of the Invention

[0005] In view of the above problems existing in the prior art, a dispensing valve with a reflux structure provided by the present invention is internally designed with a glue back-suction structure, which can well suck the residual glue inside the dispensing tube back into the valve body at the moment of stopping dispensing, and well avoid the phenomenon of dripping glue or wire drawing.

[0006] To achieve the above invention purpose, the technical scheme adopted by the present invention is as follows:

[0007] A dispensing valve with a reflux structure includes a dispensing valve body, a dispensing valve piston, and a dispensing valve stem. Inside the dispensing valve body, a power chamber, a movable chamber, a glue inlet chamber, a control chamber, and a slide bar chamber are sequentially arranged.

[0008] The dispensing valve piston is disposed in the power chamber, and vent holes are respectively disposed on the side walls of the power chamber on the upper and lower sides of the dispensing valve piston.

[0009] The dispensing valve stem is sequentially provided with a first part, a second part, and a third part.

[0010] The first part is located in the movable chamber and is slidably and sealingly connected to the movable chamber.

[0011] A glue passing ring is disposed between the glue inlet chamber and the control chamber, and a glue passing hole is disposed on the glue passing ring.

[0012] The second part is located in the glue passing hole, and the outer diameter of the second part is smaller than the inner diameter of the glue passing hole.

[0013] The third part is located in the slide rod chamber and is slidably and sealingly connected to the slide rod chamber.

[0014] The upper end of the first part is connected to the lower end of the dispensing valve piston, and the dispensing valve piston drives the dispensing valve stem to move downward so that the lower end surface of the first part fits against the upper end surface of the glue passing ring to seal the glue passing hole.

[0015] The outer diameter of the first part is smaller than the inner diameter of the glue inlet chamber, and the outer diameter of the third part is smaller than or equal to the inner diameter of the control chamber and larger than the outer diameter of the second part.

[0016] A glue inlet communicating with the glue inlet chamber is disposed on the side wall of the glue inlet chamber, and a glue outlet penetrating through the dispensing valve body is disposed on the side wall of the control chamber, and a dispensing tube is connected to the glue outlet.

[0017] In one embodiment, a threaded hole is disposed on the lower end surface of the dispensing valve piston, and a thread is disposed on the side wall of the upper end of the first part, and the upper end of the first part is screwed into the threaded hole on the dispensing valve piston.

[0018] In one embodiment, the lower end surface of the first part is rounded, and a tapered counterbore is disposed at the upper end of the glue passing hole.

[0019] In one embodiment, a first sealing ring is arranged in the movable cavity, and the first sealing ring is sleeved outside the first part to achieve a sliding sealing connection between the first part and the movable cavity. A first softening agent hole is arranged at a position corresponding to the first sealing ring on the side wall of the movable cavity. The outer end of the first softening agent hole is connected with a first softening agent pipe made of a transparent material. The first sealing ring includes two upper and lower first sealing rings, and a gap is arranged between the two upper and lower first sealing rings. The first softening agent hole communicates with the gap located between the two upper and lower first sealing rings;

[0020] A second sealing ring is arranged in the sliding rod cavity, and the second sealing ring is sleeved outside the third part to achieve a sliding sealing connection between the third part and the sliding cavity. A second softening agent hole is arranged at a position corresponding to the second sealing ring on the side wall of the sliding cavity. The outer end of the second softening agent hole is connected with a second softening agent pipe made of a transparent material. The second sealing ring includes two upper and lower second sealing rings, and a gap is arranged between the two upper and lower second sealing rings. The second softening agent hole communicates with the gap located between the two upper and lower second sealing rings.

[0021] Compared with the prior art, a dispensing valve with a reflux structure provided by the present invention forms a glue sucking-back structure by arranging a dispensing valve stem, a glue inlet cavity and a control cavity inside the device. The dispensing valve stem moves up and down to change the volume of the inner cavities of the glue inlet cavity and the control cavity to form negative pressure, so as to suck back the residual glue inside the dispensing tube into the dispensing valve body instantaneously when the dispensing machine stops dispensing, thus well avoiding the phenomenon of dripping glue or drawing wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a three-dimensional structural schematic diagram of a dispensing machine including the present invention;

[0023] Figure 2 is an internal structural schematic diagram of a dispensing machine including the present invention;

[0024] Figure 3 is Figure 1 the internal structural schematic diagram of the control valve included in the dispensing machine in;

[0025] Figure 4 is a three-dimensional structural schematic diagram of the present invention;

[0026] Figure 5 is an internal structural schematic diagram of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", etc. are based on the orientation or positional relationships shown in the drawings. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0028] In addition, the terms "first" and "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means more than two, unless otherwise specifically and clearly defined.

[0029] In the present invention, unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled", "fixed", etc. should be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In the present invention, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0031] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0032] As Figures 1-5 shown, for the convenience of description, the orientation references of "upper", "lower", "left", "right", "front", and "rear" in the present invention are based on the orientation shown in the appended Figure 1 figure;

[0033] A dispensing machine includes a housing 1, a glue inlet valve group 2, and a dispensing valve 3. A glue storage cavity 101 is provided inside the housing 1. The glue inlet valve group 2 and the dispensing valve 3 are respectively arranged on the side walls of the housing 1. The glue outlet of the glue inlet valve group 2 and the glue inlet of the dispensing valve 3 are respectively communicated with the glue storage cavity 101.

[0034] Preferably, the glue outlet of the glue inlet valve group 2 is communicated with the glue inlet of the glue storage cavity 101, the glue inlet of the dispensing valve 3 is communicated with the glue outlet of the glue storage cavity 101, and the glue inlet of the glue storage cavity 101 is located on the upper side wall of the glue storage cavity 101, and the glue outlet of the glue storage cavity 101 is located on the lower side wall of the glue storage cavity 101. In this way, the glue temporarily stored in the glue storage cavity 101 will enter and exit the glue storage cavity 101 in an orderly manner according to the principle of first in first out, avoiding the situation that the glue that enters the glue storage cavity 101 first is output from the glue storage cavity 101 later or accumulates in the glue storage cavity 101, resulting in the glue being stored in the glue storage cavity 101 for too long and affecting the quality of the glue.

[0035] The dispensing valve 3 includes a dispensing valve body 301, a dispensing valve piston 302, and a dispensing valve stem 303. Inside the dispensing valve body 301, a power cavity 3011, a movable cavity 3012, a glue inlet cavity 3013, a control cavity 3014, and a slide bar cavity 3015 are sequentially arranged from top to bottom.

[0036] The dispensing valve piston 302 is arranged in the power cavity 3011. First air vents 304 are respectively arranged on the side walls of the power cavity 3011 on the upper and lower sides of the dispensing valve piston 302. The first air vents 304 are externally connected to an external air source, and cooperate with a corresponding reversing valve to control the air inlet and outlet directions of the upper and lower two first air vents 304, thereby driving the dispensing valve piston 302 to move up and down in the power cavity 3011.

[0037] The dispensing valve stem 303 is successively provided with a first part 3031, a second part 3032 and a third part 3033.

[0038] The first part 3031 is located in the movable cavity 3012 and is slidably and sealingly connected to the movable cavity 3012.

[0039] A glue-passing ring 305 is arranged between the glue inlet cavity 3013 and the control cavity 3014, and a glue-passing hole 3051 is arranged on the glue-passing ring 305.

[0040] The second part 3032 is located in the glue-passing hole 3051, and the outer diameter of the second part 3032 is smaller than the inner diameter of the glue-passing hole 3051, so that a glue-passing gap for the glue to pass through is formed between the second part 3032 and the glue-passing hole 3051.

[0041] The third part 3033 is located in the slide rod cavity 3015 and is slidably and sealingly connected to the slide rod cavity 3015.

[0042] The upper end of the first part 3031 is connected to the lower end of the dispensing valve piston 302. Specifically, a threaded hole is arranged on the lower end face of the dispensing valve piston 302, threads are arranged on the side wall of the upper end of the first part 3031, and the upper end of the first part 3031 is screwed into the threaded hole on the lower end face of the dispensing valve piston 302 to realize the connection between the two. The dispensing valve piston 302 drives the dispensing valve stem 303 to move downward so that the lower end face of the first part 3031 fits against the upper end face of the glue-passing ring 305 to seal the glue-passing hole 3051.

[0043] The outer diameter of the first part 3031 is smaller than the inner diameter of the glue inlet cavity 3013, and the outer diameter of the third part 3033 is smaller than or equal to the inner diameter of the control cavity 3014 and larger than the outer diameter of the first part 3031.

[0044] The glue inlet of the dispensing valve 3 is arranged on the side wall of the glue inlet cavity 3013 and is communicated with the glue inlet cavity 3013. An outlet is arranged on the side wall of the control cavity 3014 and penetrates through the dispensing valve body 301, and a dispensing tube 4 is connected to the outlet.

[0045] In this embodiment, a threaded adjustment hole 306 communicating with the power chamber 3011 is provided on the top wall of the dispensing valve body 301. An adjustment screw 307 is screwed into the threaded adjustment hole 306, and a fastening nut 308 is screwed onto the adjustment screw 307 above the threaded adjustment hole 306. By controlling the distance that the adjustment screw 307 extends into the power chamber 306, the distance of the up-and-down movement of the dispensing valve piston 302 is limited. Since the cavity formed by the glue inlet chamber 3013 and the control chamber 3014 decreases in volume as the dispensing valve stem 303 moves downward, the decreased volume is equal to the volume of the third part 3033 retracting downward into the slide rod chamber 3015 minus the increased volume of the first part 3031 entering the glue inlet chamber 3013. Due to the change in this part of the volume generating negative pressure in the glue inlet chamber 3013 and the control chamber 3014, this part of the volume will be filled by the backflow of the glue in the dispensing tube 4 communicating with the glue outlet of the dispensing valve body 301. Therefore, the distance of the up-and-down movement of the dispensing valve piston 302 directly determines the magnitude of the negative pressure generated in the glue inlet chamber 3013 and the control chamber 3014 during the downward movement of the dispensing valve stem 303, thereby controlling the magnitude of the backflow volume of the glue in the dispensing tube 4 communicating with the glue outlet of the dispensing valve body 301. On the other hand, it is also possible to adjust and control the size of the opening between the lower end surface of the first part 3031 and the upper end surface of the glue-passing ring 305 during the first period when it is opened and the second period when it is closed, so as to limit the flow rate and velocity of the glue passing between the lower end surface of the first part 3031 and the upper end surface of the glue-passing ring 305.

[0046] In this embodiment, the glue inlet valve group 2 includes a switching valve 201, a glue inlet valve 202, and a control valve 203. The switching valve 201, the glue inlet valve 202, and the control valve 203 are connected in sequence. The control valve 203 includes a control valve body 2031, a control valve piston 2032, and a control valve stem 2033. Inside the control valve body 2031, there are a glue inlet channel 20311, a glue outlet channel 20312, a piston channel 20313, and a valve stem channel 20314. The glue inlet channel 20311 is located above the glue outlet channel 20312 and is in communication with the glue outlet channel 20312. The control valve piston 2032 is arranged in the piston channel 20313, and the control valve stem 2033 is arranged in the valve stem channel 20314. A sealing ring 204 is provided at the connection between the glue outlet channel 20312 and the housing 1. One end of the control valve stem 2033 is connected to the control valve piston 2032. Second vent holes 205 are respectively provided on the side walls of the piston channel 20313 on both sides of the control valve piston 2032. The second vent holes 205 are externally connected to an external air source and cooperate with corresponding reversing valves to control the air inlet and outlet directions of the left and right second vent holes 205, thereby driving the control valve piston 2032 to move left and right in the piston channel 20313. Furthermore, the control valve piston 2032 drives the control valve stem 2033 to approach the sealing ring 204 so that its end is inserted into the central hole of the sealing ring 204 to block the glue outlet channel 20312. At the same time, a proximity sensor 206 for detecting the position of the control valve stem 2033 is provided on the end face of the glue inlet valve group 2 away from the housing 1. The proximity sensor 206 transmits its detection signal to a controller that cooperates with the dispensing machine provided by the present invention. The controller can control the air inlet time and air inlet direction of the air source that supplies air to the dispensing machine according to the control program inside it and the detection signals of each sensor, realizing the automatic control of the opening and closing action of the control valve 203.

[0047] In this embodiment, the lower end face of the first part 3031 and the edge of the control valve stem 2033 near the sealing ring 204 are respectively rounded. Tapered counterbores are respectively provided at the upper end of the glue passing hole 3051 and the end of the sealing ring 204 near the control valve stem 2033. Therefore, sealing surfaces are respectively formed between the lower end face of the first part 3031 and the upper end of the glue passing hole 3051, and between the end of the control valve stem 2033 near the sealing ring 204 and the end of the sealing ring 204 near the control valve stem 2033, so as to achieve the sealing between the lower end face of the first part 3031 and the upper end of the glue passing hole 3051, and between the end of the control valve stem 2033 near the sealing ring 204 and the end of the sealing ring 204 near the control valve stem 2033.

[0048] In this embodiment, a first sealing ring 309 is provided in the movable cavity 3012, and the first sealing ring 309 is sleeved outside the first part 3031 to achieve a sliding sealing connection between the first part 3031 and the movable cavity 3012. A first softening agent hole is provided at a position corresponding to the first sealing ring 309 on the side wall of the movable cavity 3012. The outer end of the first softening agent hole is connected to a first softening agent pipe 310 made of a transparent material. The first sealing ring 309 includes two upper and lower first sealing rings 309, and there is a gap between the two upper and lower first sealing rings 309. The first softening agent hole communicates with the gap between the two upper and lower first sealing rings 309. Through the first softening agent pipe 310 and the first softening agent hole, it is convenient to inject a softening agent between the first sealing ring 309 and the first part 3031 of the dispensing valve stem 303. Because when the lower end of the first part 3031 reciprocates into and out of the glue inlet cavity 3013, glue is inevitably adhered to its surface. Therefore, injecting a softening agent between the first sealing ring 309 and the first part 3031 of the dispensing valve stem 303 can not only lubricate between the first sealing ring 309 and the first part 3031 of the dispensing valve stem 303, but also, by the action of the softening agent, peel off the glue adhered to the first part 3031 of the dispensing valve stem 303. On the other hand, after the first sealing ring 309 and the first part 3031 of the dispensing valve stem 303 cooperate with each other for a long time, when the first sealing ring 309 is worn or aged, the gap between the first sealing ring 309 and the first part 3031 of the dispensing valve stem 303 will become larger. Therefore, the glue adhered to the lower end of the first part 3031 may enter the first softening agent pipe 310 through the first softening agent hole as the first part 3031 moves upward. Because the first softening agent pipe 310 is made of a transparent material, when the user finds traces of glue in the first softening agent pipe 310, it indicates that the gap between the first sealing ring 309 and the first part 3031 of the dispensing valve stem 303 is too large at this time, and the first sealing ring 309 or the dispensing valve stem 303 needs to be repaired or replaced, which plays a very good warning role. Preferably, a dust cover is provided at the end of the first softening agent pipe 310 to prevent external dust or foreign objects from entering the first softening agent pipe 310 and even affecting the sealing performance between the first sealing ring 309 and the first part 3031 of the dispensing valve stem 303.

[0049] Similarly, a second sealing ring 311 is provided in the sliding rod cavity 3015, and the second sealing ring 3012 is sleeved on the outside of the third part 3033 to realize a sliding sealing connection between the third part 3033 and the sliding cavity 3015, and a second softener hole is provided at a position corresponding to the second sealing ring 311 on the side wall of the sliding cavity 3015, and the outer end of the second softener hole is connected to a second softener tube 312 made of a transparent material, and the second sealing ring 311 includes two upper and lower second sealing rings 311, and a gap is provided between the upper and lower second sealing rings 311, and the second softener hole is connected to the gap between the upper and lower second sealing rings 311; the structure and function of the second sealing ring 311 and the second softener tube 312 here are the same as those of the first sealing ring 309 and the first softener tube 310 mentioned above, and therefore, they are not repeated here.

[0050] Similarly, a third sealing ring 207 is provided in the valve stem channel 20314, and the third sealing ring 207 is sleeved on the outside of the control valve stem 2033, and a third softener hole is provided on the side wall of the valve stem channel 20314 at a position corresponding to the third sealing ring 207, and the outer end of the third softener hole is connected to a third softener tube 208 made of transparent material, and the third sealing ring 207 includes two left and right third sealing rings 207, and a gap is provided between the two left and right third sealing rings 207, and the third softener hole is connected to the gap between the two left and right third sealing rings 207; the structure and function of the third sealing ring 207 and the third softener tube 208 here are the same as those of the above-mentioned first sealing ring 309 and the first softener tube 310, so they are not repeated here.

[0051] In the present embodiment, a driving chamber 102 is arranged inside the shell body above the glue storage chamber 101, a lead screw nut 103 is arranged inside the driving chamber 102, a driving motor 4 is arranged above the shell body 1, the main shaft of the driving motor 4 passes through the top wall of the shell body 1 and is transmission-connected with the lead screw nut 103, a piston rod 104 is arranged inside the glue storage chamber 101, a thread is arranged on the side wall at the upper end of the piston rod 104, the upper end of the piston rod 104 passes through the top of the glue storage chamber 101 and is threadedly connected with the lead screw nut 103, a reducer 5 is arranged between the shell body 1 and the driving motor 4, the driving motor 4 drives the lead screw nut 103 to rotate through the reducer 5 to realize the up and down movement of the piston rod 104; the driving motor 4 can realize precise control of the lead screw nut 103 through the reducer 5, thereby greatly improving the accuracy of the dispensing operation of the dispensing machine provided by the present invention.

[0052] In this embodiment, a heating pipe and a temperature sensor are provided at a position on the side wall of the housing 1 corresponding to the glue storage cavity 101. The heating pipe is designed to heat the glue stored inside the glue storage cavity 101, so as to always ensure good fluidity of the glue, avoid the glue from solidifying in the glue storage cavity 101 and affecting the effect of the entire dispensing operation. Secondly, the temperature sensor detects the temperature of the glue in the glue storage cavity 101 at any time, and the temperature sensor transmits its detection signal to the controller that cooperates with the dispensing machine provided by the present invention. The controller can control the heating duration and the on / off time point of the heating pipe according to the control program inside it and the detection signal of the temperature sensor, avoiding the glue from solidifying due to overheating or overcooling, and realizing the automatic control of the heating action of the heating pipe.

[0053] In this embodiment, pressure sensors 7 for detecting the glue inlet pressure inside the glue storage cavity 101 and the glue inlet valve 202 are respectively provided on the side walls of the housing 1 and the glue inlet valve 202. The pressure sensors 7 transmit their detection signals to the controller that cooperates with the dispensing machine provided by the present invention. The controller can control the glue inlet speed of the device supplying glue to the dispensing machine according to the control program inside it and the detection signals of the respective pressure sensors 7, and cooperate with the above-mentioned respective proximity sensors 206, temperature sensors 103 and other sensors to realize the automatic control of the dispensing action of the entire dispensing machine, greatly improving the efficiency and accuracy of the entire dispensing machine operation.

[0054] The back suction principle of a dispensing machine shown in this embodiment is as follows: Before the dispensing valve piston 302 drives the dispensing valve stem 303 to move downward, the glue inlet valve group 2 has stopped supplying glue, and at the same time, the drive motor 4 also stops injecting the glue in the glue storage cavity 101 into the glue inlet cavity 3013.

[0055] During the process of the dispensing valve piston 302 driving the dispensing valve stem 303 to move downward, since the outer diameter of the third part 3033 is less than or equal to the inner diameter of the control cavity 3014 and greater than the outer diameter of the first part 3031, and at the same time, the distance that the third part 3033 retracts from the control cavity 3014 into the slide rod cavity 3015 is equal to the distance that the first part 3031 enters the glue inlet cavity 3013, but the outer diameter of the third part 3033 is greater than the outer diameter of the first part 3031.

[0056] Before the lower end surface of the first part 3031 is not in contact with the upper end surface of the glue-passing ring 305, the glue inlet cavity 3013 and the control cavity 3014 are in communication with each other. Therefore, as the dispensing valve stem 303 moves downward, the volume of the cavity formed by the glue inlet cavity 3013 and the control cavity 3014 decreases due to the volume occupied by the dispensing valve stem 303 in the glue inlet cavity 3013 and the control cavity 3014. The amount of volume reduction is equal to the volume of the third part 3033 retracting downward into the slide rod cavity 3015 minus the increased volume of the first part 3031 entering the glue inlet cavity 3013. Since this change in volume will generate negative pressure in the glue inlet cavity 3013 and the control cavity 3014, the glue in the dispensing tube 4 communicated with the glue outlet of the dispensing valve body 301 will backfill to fill this part of the volume, so as to achieve the back suction effect. Finally, as the dispensing valve stem 303 moves downward, the lower end surface of the first part 3031 of the dispensing valve stem 303 is in contact with the upper end surface of the glue-passing ring 305 to seal the glue-passing hole 3051, and the glue inlet of the control cavity 3014 is completely sealed, avoiding the phenomenon of dripping or wire drawing of the glue in the dispensing tube 4 when dispensing stops.

[0057] Preferably, a dispensing machine shown in this embodiment can adjust the number of the housing 1, the glue inlet valve group 2, and the dispensing valve 3 included in a dispensing machine according to the types of glue composition. For example, when performing the dispensing operation of AB glue on the market at present, when using the dispensing machine shown in this embodiment for dispensing, two sets of the housing 1, the glue inlet valve group 2, and the dispensing valve 3 can be set on the same dispensing machine. Finally, the AB glue coming out of the glue outlets of the two dispensing valves 3 is mixed into a dispensing tube 4 through a pipeline to realize the dispensing operation of AB glue. At the same time, according to the mixing ratio of AB glue, the dispensing speed of A or B glue can be controlled respectively to match the ratio of the components of different mixed glues.

[0058] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0059] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it cannot be understood as a limitation to the scope of the invention patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent of the present invention should be subject to the appended claims.

Claims

1. A dispensing valve with a reflux structure, characterized in that, It includes a dispensing valve body, a dispensing valve piston and a dispensing valve stem. Inside the dispensing valve body, there are successively arranged a power chamber, a movable chamber, a glue inlet chamber, a control chamber and a slide bar chamber. The dispensing valve piston is arranged in the power chamber. Vent holes are respectively arranged on the side walls of the power chamber on the upper and lower sides of the dispensing valve piston. The dispensing valve stem is successively provided with a first part, a second part and a third part. The first part is located in the movable chamber and is slidably and sealingly connected to the movable chamber. A glue passing ring is arranged between the glue inlet chamber and the control chamber, and a glue passing hole is arranged on the glue passing ring. The second part is located in the glue passing hole, and the outer diameter of the second part is smaller than the inner diameter of the glue passing hole. The third part is located in the slide bar chamber and is slidably and sealingly connected to the slide bar chamber. The upper end of the first part is connected to the lower end of the dispensing valve piston. The dispensing valve piston drives the dispensing valve stem to move downward so that the lower end surface of the first part fits against the upper end surface of the glue passing ring to seal the glue passing hole. The outer diameter of the first part is smaller than the inner diameter of the glue inlet chamber. The outer diameter of the third part is smaller than or equal to the inner diameter of the control chamber and larger than the outer diameter of the first part. A glue inlet communicating with the glue inlet chamber is arranged on the side wall of the glue inlet chamber. An outlet glue port penetrating the dispensing valve body is arranged on the side wall of the control chamber, and a dispensing tube is connected to the outlet glue port.

2. The dispensing valve with a reflux structure according to claim 1, characterized in that, A threaded hole is arranged on the lower end surface of the dispensing valve piston. Threads are arranged on the side wall of the upper end of the first part, and the upper end of the first part is screwed into the threaded hole on the dispensing valve piston.

3. The dispensing valve with a reflux structure according to claim 2, characterized in that, The lower end surface of the first part is processed with a fillet, and a tapered counterbore is arranged at the upper end of the glue passing hole.

4. The dispensing valve with a reflux structure according to claim 3, characterized in that, A first sealing ring is arranged in the movable chamber, and the first sealing ring is sleeved outside the first part to realize the slidable and sealing connection between the first part and the movable chamber. A first softening agent hole is arranged at the position corresponding to the first sealing ring on the side wall of the movable chamber. The outer end of the first softening agent hole is connected with a first softening agent tube made of transparent material. The first sealing ring includes two upper and lower first sealing rings, and there is a gap between the two upper and lower first sealing rings. The first softening agent hole communicates with the gap between the two upper and lower first sealing rings. A second sealing ring is arranged in the slide bar chamber, and the second sealing ring is sleeved outside the third part to realize the slidable and sealing connection between the third part and the sliding chamber. A second softening agent hole is arranged at the position corresponding to the second sealing ring on the side wall of the sliding chamber. The outer end of the second softening agent hole is connected with a second softening agent tube made of transparent material. The second sealing ring includes two upper and lower second sealing rings, and there is a gap between the two upper and lower second sealing rings. The second softening agent hole communicates with the gap between the two upper and lower second sealing rings.

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