Oligonucleotide synthesizer

Abstract

The utility model relates to an oligonucleotide synthesizer, including casing, baroceptor, electrical proportional valve and control subassembly, the casing is provided with the intake cavity, the intake cavity is provided with the intake port and communication port, the electrical proportional valve is provided in the casing, the intake port is used for the communication with the gas source through the electrical proportional valve, and the control subassembly is used for the communication with the gas source through the gas pressure sensor. The machine shell is used for fixing a synthesis container, the communication opening is used for being matched with the synthesis container so that the liquid inlet side of the synthesis container can be communicated with the air inlet cavity and the liquid outlet side of the synthesis container can be communicated with the outside, and the air pressure sensor is arranged on the machine shell and used for detecting the air pressure of the air inlet cavity. The control assembly is electrically connected with the air pressure sensor and the electric proportional valve. The control assembly can control the electric proportional valve so as to adjust the required amount of gas introduced into the gas inlet cavity, so that residual reagents in each reaction step can be completely removed, and the quality of reaction products is ensured.

Description

Technical Field

[0001] This utility model relates to the field of oligonucleotide synthesis technology, and in particular to an oligonucleotide synthesizer. Background Technology

[0002] Because oligonucleotide synthesis requires four reagent removal processes for each additional base, the synthesis of longer DNA chains (e.g., 90 bases) necessitates hundreds of such processes. This is typically achieved by applying positive pressure to the synthesis tube using a gas source. However, the length of the synthesis process and the numerous removal steps significantly reduce the gas source pressure. This pressure decay leads to insufficient reagent removal in subsequent reaction steps, severely impacting the quality of the synthesized product. Furthermore, as the length of the oligonucleotide chain increases, the micropores on the synthesis carrier decrease, increasing gas resistance. A fixed gas source pressure also results in insufficient reagent removal in subsequent reaction steps, further affecting the quality of the synthesized product. Utility Model Content

[0003] Therefore, it is necessary to provide an oligonucleotide synthesizer.

[0004] An oligonucleotide synthesizer includes a housing, a pressure sensor, an electro-proportional valve, and a control assembly. The housing has an air inlet chamber with an air inlet and a connecting port. The electro-proportional valve is disposed within the housing. The air inlet is used to connect to a gas source via the electro-proportional valve. The housing is used to fix a synthesis container. The connecting port cooperates with the synthesis container so that the liquid inlet side of the synthesis container connects to the air inlet chamber, and the liquid outlet side of the synthesis container connects to the outside. The pressure sensor is disposed within the housing and is used to detect the pressure in the air inlet chamber. The control assembly is electrically connected to both the pressure sensor and the electro-proportional valve.

[0005] It is worth noting that the existing synthesis container has openings on both sides, with the openings serving as the inlet and outlet, respectively. The side with the inlet is the inlet side of the synthesis container, and the side with the outlet is the outlet side. The synthesis container can be tubular or dish-shaped. A tubular synthesis container can be called a synthesis tube or synthesis column, and its interior is hollow and tubular. In some embodiments, one end of the synthesis tube is conical, and the internal diameter of the conical section of the synthesis tube gradually decreases to guide the removal of residual reagents and accelerate their removal. When the synthesis container is dish-shaped, an outlet is provided at the bottom of the dish, which is the outlet side of the synthesis container.

[0006] The aforementioned oligonucleotide synthesizer has a housing that secures the synthesis container. The synthesis container, containing the synthesis carrier and reaction reagents, is placed behind the housing. Through a connecting port, the liquid inlet side of the synthesis container is connected to the air inlet chamber, and the liquid outlet side is connected to the outside. After the reaction reagents have reacted on the synthesis carrier, a gas source introduces gas into the air inlet chamber through the air inlet. This creates a positive pressure difference between the liquid inlet and outlet sides of the synthesis container, driving residual reagents to detach from the synthesis carrier and thus removing them. During the removal of residual reagents, a pressure sensor continuously monitors the pressure within the air inlet chamber. The control component acquires the pressure data from the pressure sensor and, when it detects that the air pressure in the air inlet chamber is too high or too low, adjusts the opening of the electro-proportional valve to control the amount of gas input into the air inlet chamber, thereby maintaining stable pressure within the air inlet chamber. In this way, even if the internal pressure of the gas source becomes unstable during use, such as when the gas source pressure decreases, the control component can adjust the amount of gas that needs to be introduced into the air inlet chamber by controlling the electric proportional valve, thereby stabilizing the gas pressure in the air inlet chamber and ensuring that residual reagents in each reaction step can be completely removed, thus ensuring the quality of the reaction product.

[0007] Furthermore, the inventors of this invention discovered that the various reagents used in the oligonucleotide reaction steps have different functions and therefore different viscosities. Conventional synthesis systems can only maintain a constant gas pressure, resulting in varying times required to purge each residual reagent. As the number of reaction steps increases, the length of the product on the synthesis support increases, and impurities from the reagents accumulate on the synthesis support, increasing venting resistance. At this point, even with constant pressure and extended venting time, residual reagents cannot be completely removed, thus affecting the quality of the final synthesized product. In this application, however, by adjusting the gas pressure to fully purge residual reagents, it is ensured that residual reagents from each reaction step are completely removed, thereby ensuring the quality of the reaction product.

[0008] In one embodiment, the housing is further provided with an exhaust chamber, the exhaust chamber having an exhaust port communicating with the outside, and the air intake chamber communicating with the exhaust chamber through the communication port.

[0009] In one embodiment, at least one synthesis container is further included, the synthesis container having a through-flow inlet side and an outlet side, the inlet side and the outlet side being used to fix the synthesis carrier, the synthesis container including at least one of the following configurations:

[0010] i) The synthesis container is fixed inside the air inlet chamber, and the liquid discharge side of the synthesis container abuts against the communication port of the housing;

[0011] ii) The synthesis container is fixed outside the air inlet chamber, and the liquid inlet side of the synthesis container abuts against the communication port of the housing;

[0012] iii) The communication port of the housing is used to insert the synthesis container.

[0013] In one embodiment, the number of the communication ports is set to multiple, and each communication port is used to correspond to the synthesis container.

[0014] In one embodiment, each of the communication ports corresponds to one of the synthesis containers; or

[0015] Each of the aforementioned connection ports is divided into multiple groups, and each group of connection ports corresponds to one of the aforementioned synthesis containers.

[0016] In one embodiment, a gas source is also included, which is connected to the air inlet via the electro-proportional valve.

[0017] In one embodiment, a reagent delivery mechanism is further included, which is disposed in the housing and oriented toward the air inlet chamber.

[0018] In one embodiment, the control component includes one of a PID controller, a microcontroller, and a PLC controller.

[0019] In one embodiment, a display component is also included, which is electrically connected to the PID controller.

[0020] In one embodiment, a pressure reducing valve is also included, the electro-proportional valve being used to communicate with the gas source via the pressure reducing valve.

[0021] In one embodiment, the pressure sensor is used to detect the pressure data of the intake chamber, and the control component is used to control the opening degree of the electro-proportional valve based on the pressure data of the intake chamber; and / or

[0022] The air pressure detection component is used to detect the air pressure data of the air intake chamber at a preset time interval. The control component is used to calculate the air pressure drop rate of the air intake chamber based on the air pressure data at the preset time interval. When the air pressure drop rate is less than the preset drop rate, the control component increases the opening of the electro-proportional valve. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating the principle of oligonucleotide synthesis.

[0024] Figure 2 This is a schematic diagram of the structure of an oligonucleotide synthesizer according to one embodiment.

[0025] Figure 3 This is a schematic diagram of the synthesis container of an oligonucleotide synthesizer according to one embodiment.

[0026] In the diagram, 10 is the oligonucleotide synthesizer; 100 is the housing; 200 is the pressure sensor; 300 is the electro-proportional valve; 400 is the control component; 101 is the air inlet chamber; 102 is the air inlet; 103 is the connecting port; 500 is the synthesis container; 104 is the exhaust chamber; 105 is the exhaust port; 610 is the gas cylinder; 620 is the gas flow meter; 630 is the reagent storage bottle; 710 is the display screen; 720 is the pressure reducing valve; 730 is the gas tank; 111 is the split sampler; 510 is the liquid inlet side; 520 is the liquid outlet side; and 530 is the synthesis carrier. Detailed Implementation

[0027] To facilitate understanding of this application, a more complete description will be provided below. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0031] like Figure 1 As shown, the synthesis reaction steps of oligonucleotides include the following cycle in sequence: deprotection, coupling reaction, capping, oxidation...ammonia cleavage.

[0032] Each step involves three processes: adding reaction reagents, waiting for the reaction to proceed, and removing the reagents. The process of removing reagents mainly involves adding inert gas in the forward direction to remove residual reagents, thus preparing for the next step of the reaction. It is essential to thoroughly remove any residual reagents.

[0033] To ensure that residual reagents are completely removed, such as Figure 2 and Figure 3 As shown, in one embodiment, an oligonucleotide synthesizer 10 is provided, including a housing 100, a pressure sensor 200, an electro-proportional valve 300, and a control component 400. The housing 100 has an air inlet chamber 101 with an air inlet 102 and a connecting port 103. The electro-proportional valve 300 is disposed on the housing 100. The air inlet 102 is used to connect to a gas source through the electro-proportional valve 300. The housing 100 is used to fix a synthesis container 500. The connecting port 103 cooperates with the synthesis container 500 so that the liquid inlet side 510 of the synthesis container 500 is connected to the air inlet chamber 101, and the liquid outlet side 520 of the synthesis container 500 is connected to the outside. The pressure sensor 200 is disposed on the housing 100 and is used to detect the pressure of the air inlet chamber 101. The control component 400 is electrically connected to the pressure sensor 200 and the electro-proportional valve 300.

[0034] It is worth mentioning that the existing synthesis container 500 has openings on both sides, with the openings being an inlet and an outlet, respectively. The side with the inlet is the inlet side 510 of the synthesis container 500, and the side with the outlet is the outlet side 520. The synthesis container can be tubular or dish-shaped. A tubular synthesis container can be called a synthesis tube or synthesis column, and its interior is hollow and tubular. In some embodiments, one end of the synthesis tube is conical, and the internal diameter of the conical part of the synthesis tube gradually decreases to guide the removal of residual reagents and accelerate the removal of residual reagents. When the synthesis container is dish-shaped, an outlet is opened at the bottom of the dish, and the bottom of the dish is the outlet side of the synthesis container.

[0035] The housing 100 of the aforementioned oligonucleotide synthesizer 10 can fix the synthesis container 500. After placing the synthesis container 500, which contains the synthesis carrier 530 and reaction reagents, in the housing 100, the liquid inlet side 510 of the synthesis container 500 can be connected to the air inlet chamber 101 through the communication port 103, and the liquid outlet side 520 of the synthesis container 500 can be connected to the outside. After the reaction reagents have reacted on the synthesis carrier 530, the gas source introduces gas into the air inlet chamber 101 through the air inlet port 102, which can create a positive pressure difference between the liquid inlet side 510 and the liquid outlet side of the synthesis container 500, thereby driving the residual reagents to detach from the synthesis carrier 530 and realizing the removal of residual reagents. During the removal of residual reagents, the pressure sensor 200 continuously monitors the pressure inside the air inlet chamber 101. The control component 400 acquires the pressure data from the pressure sensor 200 and, when it detects that the pressure in the air inlet chamber 101 is too high or too low, adjusts the opening of the electro-proportional valve 300 to control the amount of air input to the air inlet chamber 101, thereby maintaining a stable pressure inside the air inlet chamber 101. Thus, even if the internal pressure of the air source becomes unstable during use, such as when the air source pressure decreases, the control component 400 can still adjust the required amount of air supplied to the air inlet chamber 101 by controlling the electro-proportional valve 300, stabilizing the pressure inside the air inlet chamber 101, thereby ensuring that residual reagents from each reaction step are completely removed and ensuring the quality of the reaction product.

[0036] Furthermore, the inventors of this invention discovered that the various reagents used in the oligonucleotide reaction steps have different functions and therefore different viscosities. Conventional synthesis systems can only maintain a constant gas pressure, resulting in varying times required to purge each residual reagent. As the number of reaction steps increases, the length of the product on the synthesis support increases, and impurities from the reagents accumulate on the synthesis support, increasing venting resistance. At this point, even with constant pressure and extended venting time, residual reagents cannot be completely removed, thus affecting the quality of the final synthesized product. In this application, however, by adjusting the gas pressure to fully purge residual reagents, it is ensured that residual reagents from each reaction step are completely removed, thereby ensuring the quality of the reaction product.

[0037] In one embodiment, the housing 100 further includes an exhaust chamber 104, which has an exhaust port 105 communicating with the outside. In one embodiment, the exhaust port 105 communicates with the atmosphere, and the intake chamber 101 communicates with the exhaust chamber 104 through the communication port 103. The exhaust chamber 104 provides a space relatively isolated from the external environment of the housing 100, minimizing product contact with the external environment and preventing product contamination by impurities. Furthermore, the exhaust chamber 104 communicates with the outside through the exhaust port 105, facilitating the formation of a pressure difference between the intake chamber 101 and the exhaust chamber 104.

[0038] In one embodiment, the oligonucleotide synthesizer 10 further includes at least one synthesis container 500, the synthesis container 500 having a through inlet side 510 and a outlet side 520, the inlet side 510 and the outlet side 520 being used to fix a synthesis carrier 530, the synthesis container 500 including at least one of the following configurations, namely at least one of i, ii and iii, and there can be multiple synthesis containers 500, so that the configuration of the synthesis containers 500 can be diverse.

[0039] In one embodiment, the synthesis container is fixed within the air inlet chamber, and the drain side of the synthesis container abuts against the communication port of the housing. In this configuration, the drain side of the synthesis container abuts against the inner surface of the housing near the communication port, so that the inlet of the synthesis container is connected to the communication port. Thus, the air inlet chamber, the interior of the synthesis container, and the communication port are sequentially connected, thereby easily creating a positive pressure difference between the inlet and drain sides of the synthesis container, which can effectively remove residual reagents from the synthesis carrier. For example, the communication port is located at the inner bottom of the housing, and the drain side of the synthesis container is placed and abuts against the inner bottom of the housing, with the drain port connected to the communication port. In one embodiment, a limiting ring is provided around the communication port at the inner bottom of the housing, and the synthesis container is placed within the limiting ring to fix the synthesis container. For example, the housing is provided with a fixing mechanism for fixing the synthesis container, such as a clamping component, a snap-fit ​​component, a magnetic suction component, etc., so as to fix the synthesis container in the air inlet cavity of the housing, and make the liquid discharge side of the synthesis container abut against the communication port of the housing.

[0040] like Figure 2 As shown, in one embodiment, the synthesis container 500 is fixed outside the air inlet chamber 101. In this embodiment, the synthesis container 500 is disposed inside the exhaust chamber 104, and the liquid inlet side 510 of the synthesis container 500 abuts against the communication port 103 of the housing 100. In this configuration, the synthesis container 500 is fixed on the side of the housing 100 opposite to the air inlet chamber 101. In one embodiment, a limiting ring is provided around the communication port 103 on the outer surface of the housing 100, and the synthesis container 500 is inserted into the limiting ring to fix the synthesis container 500. Alternatively, the outer side of the housing 100 may be provided with a fixing mechanism for fixing the synthesis container 500, such as a clamping assembly, a snap-fit ​​assembly, or a magnetic suction assembly, thereby fixing the synthesis container 500 on the side of the housing 100 opposite to the air inlet chamber 101, and ensuring that the liquid inlet side 510 of the synthesis container 500 abuts against the communication port 103 of the housing 100.

[0041] In one embodiment, the communication port of the housing is used to insert a synthesis container. In this configuration, the synthesis container is directly inserted into the communication port, and the outer surface of the synthesis container abuts against the side wall of the communication port, thereby facilitating the fixation of the synthesis container. Simultaneously, the air inlet chamber is connected to the atmosphere through the interior of the synthesis container, creating a positive pressure difference. In another embodiment, the synthesis container and the side wall of the communication port are interference-fitted, thereby sealing the gap between the synthesis container and the side wall of the communication port to prevent air leakage. This allows the air pressure in the air inlet chamber to better act on the reaction reagents in the synthesis container, which is beneficial for removing residual reagents.

[0042] In one embodiment, the number of communication ports 103 is set to multiple, and each communication port 103 is configured to correspond to a synthesis container 500. In one embodiment, each communication port 103 corresponds to one synthesis container 500. In this embodiment, multiple synthesis containers 500 can be configured to carry out multiple reactions simultaneously. Alternatively, the communication ports 103 are divided into multiple groups, and each group of communication ports 103 corresponds to one synthesis container 500. In this embodiment, multiple communication ports 103 are all connected to the interior of the synthesis container 500, thereby diverting the gas from the inlet chamber 101 to the interior of the synthesis container 500. Some communication ports 103 can guide the gas to blow gas to specific locations, thereby better removing residual reagents on the synthesis carrier 530.

[0043] In one embodiment, the oligonucleotide synthesizer 10 further includes a gas source connected to the air inlet 102 via the electro-proportional valve 300. For example, the gas source is a gas tank 730 containing a non-reactive gas that does not participate in oligonucleotide synthesis. For instance, the non-reactive gas may be an inert gas to avoid reaction with the oligonucleotide raw materials and to prevent corrosion of the equipment. Another example is an air pump used to draw ambient air into the air inlet chamber 101.

[0044] In one embodiment, the oligonucleotide synthesizer 10 further includes a reagent delivery mechanism disposed in the housing 100 and facing the air inlet chamber 101. The reagent delivery mechanism is used to deliver the reaction reagents for oligonucleotide synthesis into the synthesis container 500, achieving automated reagent addition and improving reaction efficiency. In this embodiment, the reagent delivery mechanism includes a gas cylinder 610, a gas flow meter 620, and a reagent storage bottle 630 connected in sequence. In this embodiment, the gas delivery pipe from the gas flow meter 620 is inserted above the reagent storage bottle 630, and the liquid outlet pipe of the reagent storage bottle 630 extends from the bottom of the reagent storage bottle 630 to the air inlet chamber 101, facing the synthesis container 500. Thus, the gas from the gas cylinder 610 drives the reagent in the reagent storage bottle 630 to the synthesis container 500, achieving automated liquid addition. In this embodiment, there are multiple reagent storage bottles 630. The oligonucleotide synthesizer 10 also includes a split sampler 111. The gas flow meter 620 is connected to each reagent storage bottle 630 through the split sampler 111. Each reagent storage bottle can store different reagents, that is, each reagent storage bottle 630 is set to correspond to the synthesis container 500.

[0045] In one embodiment, the control component 400 includes a PID controller. The PID controller consists of a proportional unit P, an integral unit I, and a derivative unit D. In this embodiment, the PID controller is used to acquire air pressure data from the air pressure sensor 200, and when it detects that the air pressure in the intake chamber 101 is too high or too low, it adjusts the opening of the electro-proportional valve 300 to control the amount of air input to the intake chamber 101, thereby maintaining stable air pressure in the intake chamber 101. In this embodiment, the PID controller combined with the electro-proportional valve is a simple and practical control method with high reliability. Of course, the control component 400 can also be implemented in other ways, such as by a computer. Compared with the complex control component 400 such as a computer, the PID controller in this solution has a smaller size and can still achieve control functions. In other embodiments, the control component can also be a microcontroller or a PLC controller, both of which can achieve control functions.

[0046] In one embodiment, the oligonucleotide synthesizer 10 further includes a display component electrically connected to the PID controller. Specifically, the display component includes a display screen 710. The display screen 710 of the display component can display the PID controller readings and operation keys, thereby facilitating the adjustment of different modes.

[0047] In one embodiment, the oligonucleotide synthesizer 10 further includes a pressure reducing valve 720. The electro-proportional valve 300 is used to communicate with the gas source 730 through the pressure reducing valve 720. The gas in the gas source is under high pressure. The pressure reducing valve 720 is used to reduce the output pressure of the gas source to a more suitable level to avoid excessive pressure release.

[0048] In one embodiment, the pressure detection component is used to detect the pressure data of the air inlet chamber at preset time intervals. The control component is also used to calculate the pressure drop rate of the air inlet chamber based on the pressure data at the preset time intervals. When the pressure drop rate is less than a preset drop rate, the control component increases the opening of the electro-proportional valve. This is because a slow or no pressure drop rate indicates that the pressure in the air inlet chamber is insufficient to remove residual reagents from the synthesis carrier. In this case, the control component will increase the opening of the electro-proportional valve to remove reagents in a shorter time, thereby improving the efficiency of the entire synthesis reaction.

[0049] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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, they should be considered to be within the scope of this specification.

[0050] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. An oligonucleotide synthesizer characterized in that, The device comprises a casing, an air pressure sensor, an electric proportional valve and a control assembly, the casing is provided with an air inlet cavity, the air inlet cavity is provided with an air inlet and a communication port, the electric proportional valve is arranged in the casing, the air inlet is used to communicate with an air source through the electric proportional valve, the casing is used to fix a synthesis container, the communication port is used to cooperate with the synthesis container to make a liquid inlet side of the synthesis container communicate with the air inlet cavity and make a liquid outlet side of the synthesis container communicate with the outside, the air pressure sensor is arranged in the casing and is used to detect the air pressure of the air inlet cavity, and the control assembly is electrically connected with the air pressure sensor and the electric proportional valve respectively.

2. The oligonucleotide synthesizer of claim 1, wherein, The casing is further provided with an air outlet cavity, the air outlet cavity is provided with an air outlet communicating with the outside, and the air inlet cavity communicates with the air outlet cavity through the communication port.

3. The oligonucleotide synthesizer of claim 1, wherein, The device further comprises at least one synthesis container, the synthesis container is provided with a through liquid inlet side and a liquid outlet side, the liquid inlet side and the liquid outlet side are used to fix a synthesis carrier, and the synthesis container comprises at least one of the following arrangement modes: i) the synthesis container is fixed in the air inlet cavity, and the liquid outlet side of the synthesis container abuts against the communication port of the casing; ii) the synthesis container is fixed outside the air inlet cavity, and the liquid inlet side of the synthesis container abuts against the communication port of the casing; iii) the communication port of the casing is used to pass through the synthesis container.

4. The oligonucleotide synthesizer of claim 1, wherein, The number of the communication ports is multiple, and each communication port is used to correspond to the arrangement of the synthesis container.

5. The oligonucleotide synthesizer of claim 1, wherein, Each communication port corresponds to the arrangement of one synthesis container; or Each communication port is divided into multiple groups, and each group of communication ports corresponds to the arrangement of one synthesis container.

6. The oligonucleotide synthesizer of claim 1, wherein, The device further comprises an air source, the air source communicates with the air inlet through the electric proportional valve.

7. The oligonucleotide synthesizer of claim 1, wherein, The device further comprises a reagent conveying mechanism, the reagent conveying mechanism is arranged in the casing and is arranged towards the air inlet cavity.

8. The oligonucleotide synthesizer of claim 1, wherein, The control assembly comprises one of a PID controller, a single-chip microcomputer and a PLC controller.

9. The oligonucleotide synthesizer of claim 8, wherein, The device further comprises a display assembly, the control assembly comprises a PID controller, and the display assembly is electrically connected with the PID controller.

10. The oligonucleotide synthesizer according to any one of claims 1 to 9, characterized in that The device further comprises a pressure reducing valve, and the electric proportional valve is used to communicate with the air source through the pressure reducing valve.

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