PCV valve control system

Abstract

The utility model provides a PCV valve control system. The PCV valve control system comprises a first double-node pressure switch, a second double-node pressure switch, a first relay, a third relay and an electromagnetic valve. The first double-node pressure switch is a normally open switch, the trigger pressure of the first double-node pressure switch is a first preset pressure, the second double-node pressure switch is a normally closed contact, the trigger pressure of the second double-node pressure switch is a second preset pressure, and the first preset pressure is greater than the second preset pressure; one end of the first double-node pressure switch is connected with a power supply, the other end of the first double-node pressure switch is connected with a coil of the first relay, and a first normally open contact of the first relay is connected with the first double-node pressure switch in parallel. According to the invention, the maintenance process is simple, the maintenance cost is reduced, and the working efficiency is improved.

Description

Technical Field

[0001] The present application relates to the technical field of steam pressure control, and in particular to a PCV valve control system. Background Art

[0002] The pressure control valve, also known as the PCV valve, is an important part of the safety of the thermal power generating unit system and the first line of defense for the unit's steam overpressure protection. Its starting pressure is set lower than the safety valve starting pressure, which can reduce the number of safety valve starts. When the steam pressure is too high, the PCV valve automatically opens to release the pressure, ensuring that the pressure is within the normal range, buying time for the operation of the steam turbine side, and avoiding serious accidents such as turbine overspeed or even runaway; when the pressure drops below the starting pressure, the PCV valve automatically resets, avoiding excessive power consumption loss of the unit while ensuring the safety of the unit, ensuring the economic benefits of the unit.

[0003] At present, the control strategies of most PCV valve control devices adopt PLC or controller integrated control. Under the existing control method, the instructions for PCV valve action must be triggered by the controller. When the controller fails, the PCV valve will not work, thereby affecting work efficiency. In addition, the maintenance cost of the controller is high and the maintenance process is relatively complicated. Utility Model Content

[0004] The present application provides a PCV valve control system to solve the problems mentioned in the above background technology.

[0005] The present application provides a PCV valve control system, comprising: a first double-node pressure switch, a second double-node pressure switch, a first relay, a third relay and a solenoid valve;

[0006] The first double-node pressure switch is a normally open switch, and the triggering pressure of the first double-node pressure switch is a first preset pressure; the second double-node pressure switch is a normally closed switch, and the triggering pressure of the second double-node pressure switch is a second preset pressure, and the first preset pressure is greater than the second preset pressure;

[0007] One end of the first dual-node pressure switch is connected to a power source, the other end of the first dual-node pressure switch is connected to the coil of the first relay, and a first normally open contact of the first relay is connected in parallel with the first dual-node pressure switch;

[0008] One end of the second double-node pressure switch is connected to a power supply, the other end of the second double-node pressure switch is connected to a coil of the third relay, a first normally closed contact of the third relay is connected in series with the coil of the solenoid valve and then connected to the power supply, and a second normally open contact of the first relay is connected in series with the coil of the solenoid valve;

[0009] The solenoid valve is connected to the PCV valve.

[0010] Optionally, the PCV valve control system further includes: a second relay and a fourth relay;

[0011] The coil of the second relay is connected in parallel with the coil of the first relay, the first normally open contact of the second relay is connected in parallel with the first normally open contact of the first relay, and the second normally open contact of the second relay is connected in parallel with the second normally open contact of the first relay;

[0012] The coil of the fourth relay is connected in parallel with the coil of the third relay, and the first normally closed contact of the fourth relay is connected in series with the first normally closed contact of the third relay.

[0013] Optionally, the PCV valve control system further includes: a fifth relay, a first travel switch, and a first indicator light;

[0014] The first travel switch is installed in the first position of the PCV valve. The first position is when the PCV valve is fully opened and the valve of the PCV valve can just squeeze the position of the first travel switch. The first travel switch is connected in series with the coil of the fifth relay and then connected to the power supply. The normally open contact of the fifth relay is connected in series with the first indicator light and then connected to the power supply.

[0015] Optionally, the PCV valve control system further includes: a sixth relay, a second travel switch, and a second indicator light;

[0016] The second travel switch is installed in the second position of the PCV valve. The second position is when the PCV valve is fully closed and the valve of the PCV valve can just squeeze the position of the second travel switch. The second travel switch is connected in series with the coil of the sixth relay and then connected to the power supply. The normally open contact of the sixth relay is connected in series with the second indicator light and then connected to the power supply.

[0017] Optionally, the PCV valve control system also includes: a DCS, a first switch, a second switch, and a pressure transmitter, the DCS is connected to the pressure transmitter, the first switch and the second switch are both connected to the DCS, the first switch is connected in parallel with the first dual-node pressure switch, and the second switch is connected in parallel with the second dual-node pressure switch.

[0018] Optionally, the PCV valve control system further includes: an operating console, on which a third switch and a fourth switch are arranged, the third switch is connected in parallel with the first switch, and the fourth switch is connected in parallel with the second switch.

[0019] Optionally, the PCV valve control system further includes: a third indicator light, wherein the third indicator light is connected to the power supply.

[0020] Optionally, the PCV valve control system further includes: a fuse, wherein the fuse is connected to the power supply.

[0021] In this embodiment, the PCV valve control system includes: a first double-node pressure switch, a second double-node pressure switch, a first relay, a third relay and a solenoid valve; the first double-node pressure switch is a normally open switch, and the trigger pressure of the first double-node pressure switch is a first preset pressure, and the second double-node pressure switch is a normally closed switch, and the trigger pressure of the second double-node pressure switch is a second preset pressure, and the first preset pressure is greater than the second preset pressure; one end of the first double-node pressure switch is connected to a power supply, the other end of the first double-node pressure switch is connected to a coil of the first relay, and a first normally open contact of the first relay is connected in parallel with the first double-node pressure switch; one end of the second double-node pressure switch is connected to a power supply, the other end of the second double-node pressure switch is connected to the coil of the third relay, the first normally closed contact of the third relay is connected in series with the coil of the solenoid valve and then connected to the power supply, and the second normally open contact of the first relay is connected in series with the coil of the solenoid valve; the solenoid valve is connected to the PCV valve. Compared with the prior art, the present application realizes automatic control of the opening and closing of the PCV valve by setting a first double-node pressure switch, a second double-node pressure switch, a first relay, a second relay, a third relay and a fourth relay, and adopts a hardware loop control method, which not only reduces the failure rate, but also simplifies the maintenance process, reduces maintenance costs, and improves work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 A circuit connection diagram of a PCV valve control system provided in one embodiment of the present application;

[0024] Figure 2 A circuit connection diagram of a PCV valve control system provided by another embodiment of the present application;

[0025] Figure 3 A circuit connection diagram of a PCV valve control system provided in yet another embodiment of the present application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application is clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work also fall within the scope of protection of the present application.

[0027] Figure 1 A PCV valve control system is shown according to an embodiment of the present application. Figure 1 As shown, the system includes: a first double-node pressure switch S1, a second double-node pressure switch S2, a first relay, a third relay and a solenoid valve;

[0028] The first double-node pressure switch S1 is a normally open switch, and the triggering pressure of the first double-node pressure switch S1 is a first preset pressure. The second double-node pressure switch S2 is a normally closed contact, and the triggering pressure of the second double-node pressure switch S2 is a second preset pressure. The first preset pressure is greater than the second preset pressure.

[0029] One end of the first double-node pressure switch S1 is connected to the power supply, the other end of the first double-node pressure switch S1 is connected to the coil KA1-S of the first relay, and the first normally open contact KA1-1 of the first relay is connected in parallel with the first double-node pressure switch S1;

[0030] One end of the second double-node pressure switch S2 is connected to the power supply, the other end of the second double-node pressure switch S2 is connected to the coil KA3-S of the third relay, the first normally closed contact KA3-1 of the third relay is connected in series with the coil YV of the solenoid valve and then connected to the power supply VDD, and the second normally open contact KA1-2 of the first relay is connected in series with the coil YV of the solenoid valve;

[0031] The solenoid valve is connected to the PCV valve.

[0032] Among them, a first pressure-leading pipe is installed on the generator set, and a first double-node pressure switch S1 is installed at the outlet of the first pressure-leading pipe, which is used to lead the steam pressure in the generator set to the first double-node pressure switch S1. When the steam pressure is greater than the first preset pressure, the first double-node pressure switch S1 is closed.

[0033] Among them, a second pressure-leading pipe is installed on the generator set, and a second double-node pressure switch S2 is installed at the outlet of the second pressure-leading pipe, which is used to lead the steam pressure in the generator set to the second double-node pressure switch S2. When the steam pressure is lower than the second preset pressure, the second double-node pressure switch S2 is closed.

[0034] Furthermore, the first dual-node pressure switch S1 is a normally open switch. When the pressure is less than a first preset pressure, the first dual-node pressure switch S1 is in a disconnected state. When the pressure exceeds the first preset pressure, the first dual-node pressure switch S1 is closed. The second dual-node pressure switch S2 is a normally closed switch. When the pressure is less than a second preset pressure, the second dual-node pressure switch S2 is in a closed state. When the pressure is greater than the second preset pressure, the second dual-node pressure switch S2 is disconnected.

[0035] Among them, the first dual-node pressure switch S1 is connected to the coil KA1-S of the first relay and the power supply VDD. When the first dual-node pressure switch S1 is closed, the coil KA1-S of the first relay is energized, and the first normally open contact KA1-1 of the first relay and the second normally open contact KA1-2 of the first relay are closed.

[0036] Among them, the second double-node pressure switch S2 is connected to the coil KA3-S of the third relay and the power supply VDD. When the second double-node pressure switch S2 is closed, the coil KA3-S of the third relay is energized and the first normally closed contact KA3-1 of the third relay is disconnected.

[0037] The power supply VDD is used to provide electric energy to the coil KA1-S of the first relay and the coil KA3-S of the third relay when the first double-node pressure switch S1 and the second double-node pressure switch S2 are closed.

[0038] Among them, the solenoid valve is connected to the cylinder, the cylinder is connected to the PCV valve, the cylinder is divided into a first cavity and a second cavity by a piston rod, the piston rod is connected to the PCV valve, when the coil YV of the solenoid valve is energized, compressed air enters the first cavity through the solenoid valve, driving the piston rod to move toward the PCV valve, so that the PCV valve opens; when the coil YV of the solenoid valve loses power, compressed air enters the first cavity, driving the piston rod away from the PCV valve, so that the PCV valve closes.

[0039] The working process of the above PCV valve control system is as follows:

[0040] When the steam pressure is lower than the first preset pressure, the first double-node pressure switch S1 is disconnected, the coil KA1-S of the first relay is de-energized, the first normally open contact KA1-1 of the first relay and the second normally open contact KA1-2 of the first relay are disconnected, and the circuit where the coil YV of the solenoid valve is located is not a closed circuit. At this time, the coil YV of the solenoid valve is in a de-energized state;

[0041] When the steam pressure rises to a level greater than the first preset pressure, the first double-node pressure switch S1 is squeezed by the steam and the first double-node pressure switch S1 is closed. At this time, the second double-node pressure switch S2 is in the disconnected state, and the coil KA1-S of the first relay is energized, the first normally open contact KA1-1 and the second normally open contact KA1-2 of the first relay are closed, the coil KA3-S of the third relay is de-energized, and the first normally closed contact KA3-1 of the third relay is in the closed state, so that the coil YV of the solenoid valve is energized, so that the PCV valve is opened. After the PCV valve is opened, the steam pressure of the unit gradually decreases to less than the first preset pressure.

[0042] When the steam pressure gradually decreases to less than the second preset pressure, the second double-node pressure switch S2 is closed due to insufficient steam pressure, and the coil KA3-S of the third relay is energized, so that the first normally closed contact KA3- of the third relay is disconnected, causing the coil YV of the solenoid valve to lose power, thereby closing the PCV valve.

[0043] In this embodiment, the PCV valve control system includes: a first double-node pressure switch S1, a second double-node pressure switch S2, a first relay, a third relay and a solenoid valve; the first double-node pressure switch S1 is a normally open switch, the triggering pressure of the first double-node pressure switch S1 is a first preset pressure, the second double-node pressure switch S2 is a normally closed contact, the triggering pressure of the second double-node pressure switch S2 is a second preset pressure, and the first preset pressure is greater than the second preset pressure; one end of the first double-node pressure switch S1 is connected to a power supply, the other end of the first double-node pressure switch S1 is connected to a coil KA1-S of a first relay, and a first normally open contact KA1-1 of the first relay is connected in parallel with the first double-node pressure switch S1; one end of the second double-node pressure switch S2 is connected to a power supply, the other end of the second double-node pressure switch S2 is connected to a coil KA3-S of a third relay, the first normally closed contact KA3-1 of the third relay is connected in series with a coil YV of the solenoid valve and then connected to a power supply VDD, and a second normally open contact KA1-2 of the first relay is connected in series with the coil YV of the solenoid valve; the solenoid valve is connected to the PCV valve. Compared with the prior art, the present application realizes automatic control of the opening and closing of the PCV valve by setting a first double-node pressure switch S1, a second double-node pressure switch S2, a first relay and a third relay, and adopts a hardware loop control method, which not only reduces the failure rate, but also simplifies the maintenance process, reduces maintenance costs, and improves work efficiency.

[0044] Optionally, the PCV valve control system further includes: a second relay and a fourth relay;

[0045] The coil KA2-S of the second relay is connected in parallel with the coil KA1-S of the first relay, the first normally open contact KA2-1 of the second relay is connected in parallel with the first normally open contact KA1-1 of the first relay, and the second normally open contact KA2-2 of the second relay is connected in parallel with the second normally open contact KA1-2 of the first relay;

[0046] The coil KA4-S of the fourth relay is connected in parallel with the coil KS3-S of the third relay, and the first normally closed contact KS4-1 of the fourth relay is connected in series with the first normally closed contact KS3-1 of the third relay.

[0047] Among them, the first dual-node pressure switch S1 is connected to the coil KA1-S of the first relay, the coil KA2-S of the second relay, and the power supply VDD. When the first dual-node pressure switch S1 is closed, the coil KA1-S of the first relay and the coil KA2-S of the second relay are energized, the first normally open contact KA1-1 of the first relay and the second normally open contact KA1-2 of the first relay are closed, and the first normally open contact KA2-1 of the second relay and the second normally open contact KA2-2 of the second relay are closed.

[0048] Among them, the first relay is connected in parallel with the second relay, that is, the first relay coil and the second relay coil are connected in parallel, the first normally open contact KA1-1 of the first relay and the first normally open contact KA2-1 of the second relay are connected in parallel, and the second normally open contact KA1-2 of the first relay and the second normally open contact KA2-2 of the second relay are connected in parallel, so that when any one of the relays fails, the pressure can be adjusted by the other relay, thereby improving the reliability of the circuit.

[0049] Among them, the second dual-node pressure switch S2 is connected to the coil KA3-S of the third relay, the coil KA4-S of the fourth relay, and the power supply VDD. When the second dual-node pressure switch S2 is closed, the coil KA3-S of the third relay and the coil KA4-S of the fourth relay are energized, and the first normally closed contact KA3-1 of the third relay and the first normally closed contact KA4-1 of the fourth relay are disconnected.

[0050] Among them, the coil of the third relay is connected in parallel with the coil of the fourth relay, and the first contact of the third relay is connected in series with the first contact of the fourth relay, which is used to avoid the situation where the PCV valve is unable to relieve pressure and the steam pressure is still too high due to the coil of one of the relays being energized and closed when any one of the coils of the third relay and the fourth relay is mistakenly energized when the PCV valve is in the process of starting pressure relief.

[0051] Among them, the power supply VDD is used to provide electrical energy to the coil KA1-S of the first relay, the coil KA2-S of the second relay, the coil KA3-S of the third relay and the coil KA4-S of the fourth relay when the first double-node pressure switch S1 and the second double-node pressure switch S2 are closed.

[0052] When the steam pressure is lower than the first preset pressure, the first double-node pressure switch S1 is disconnected, the coil KA1-S of the first relay and the coil KA2-S of the second relay are de-energized, the first normally open contact KA1-1 of the first relay, the second normally open contact KA1-2 of the first relay, the first normally open contact KA2-1 of the second relay, and the second normally open contact KA2-2 of the second relay are disconnected, and the circuit where the coil YV of the solenoid valve is located is not a closed circuit. At this time, the coil YV of the solenoid valve is in a de-energized state;

[0053] When the steam pressure rises to be greater than the first preset pressure, the first double-node pressure switch S1 is squeezed by the steam and the first double-node pressure switch S1 is closed. At this time, the second double-node pressure switch S2 is in the disconnected state, and then the coil KA1-S of the first relay and the coil KA2-S of the second relay are energized, the first normally open contact KA1-1, the second normally open contact KA1-2 of the first relay, the first normally open contact KA2-1 and the second normally open contact KA2-2 of the second relay are closed, the coil KA3-S of the third relay and the coil KA4-S of the fourth relay are de-energized, the first normally closed contact KA3-1 of the third relay and the first normally closed contact KA4-1 of the fourth relay are in the closed state, so that the coil YV of the solenoid valve is energized, so that the PCV valve is opened. After the PCV valve is opened, the steam pressure of the unit gradually decreases to less than the first preset pressure.

[0054] When the steam pressure gradually decreases to less than the second preset pressure, the second double-node pressure switch S2 is closed due to insufficient steam pressure, and the coil KA3-S of the third relay and the coil KA4-S of the fourth relay are energized, so that the first normally closed contact KA3-1 of the third relay and the first normally closed contact KA4-1 of the fourth relay are disconnected, causing the coil YV of the solenoid valve to lose power, thereby closing the PCV valve.

[0055] Alternatively, see Figure 3 , the PCV valve control system also includes: a fifth relay, a first travel switch S7, and a first indicator light L1;

[0056] The first travel switch S7 is installed in the first position of the PCV valve. The first position is when the PCV valve is fully opened and the valve of the PCV valve can just squeeze the position of the first travel switch S7. The first travel switch S7 is connected in series with the coil KA5-S of the fifth relay and then connected to the power supply VDD. The normally open contact KA5-1 of the fifth relay is connected in series with the first indicator light L1 and then connected to the power supply VDD.

[0057] The first position is a position where the valve of the PCV valve can just squeeze the first travel switch S7 when the PCV valve is fully opened. Further, when the PCV valve is opened, the valve of the PCV valve squeezes the first travel switch S7, so that the first travel switch S7 is closed.

[0058] Furthermore, after the first travel switch S7 is closed, the coil KA5-S of the fifth relay connected in series with the first travel switch S7 is energized, so that the normally open contact KA5-1 of the fifth relay is closed, and the first indicator light L1 connected in series with the normally open contact KA5-1 of the fifth relay lights up. When the first indicator light L1 lights up, it prompts the staff that the current PCV valve is fully opened, so that the staff on site can directly observe the status of the PCV valve.

[0059] Alternatively, see Figure 3 , the PCV valve control system also includes a sixth relay, a second travel switch S8, and a second indicator light L2;

[0060] The second travel switch S8 is installed in the second position of the PCV valve. The second position is the position where the valve of the PCV valve can just squeeze the second travel switch S8 when the PCV valve is fully closed. The second travel switch S8 is connected in series with the coil KA6-S of the sixth relay and then connected to the power supply VDD. The normally open contact KA6-1 of the sixth relay is connected in series with the second indicator light L2 and then connected to the power supply VDD.

[0061] Among them, the second position is the position where the valve of the PCV valve can just squeeze the second travel switch S8 when the PCV valve is fully closed. Further, when the PCV valve is fully closed, the valve of the PCV valve squeezes the second travel switch S8, so that the second travel switch S8 is closed.

[0062] Furthermore, after the second travel switch S8 is closed, the coil KA6-S of the sixth relay connected in series with the second travel switch S8 is energized, so that the normally open contact KA6-1 of the sixth relay is closed, and the second indicator light L2 connected in series with the normally open contact KA6-1 of the sixth relay lights up. When the second indicator light L2 lights up, it prompts the staff that the current PCV valve is completely closed, so that the staff on site can directly observe the status of the PCV valve.

[0063] Alternatively, see Figure 2The PCV valve control system also includes: a DCS, a pressure transmitter, a first switch S3 and a second switch S4. The DCS is connected to the pressure transmitter. The first switch S3 and the second switch S4 are both connected to the DCS. The first switch S3 is connected in parallel with the first double-node pressure switch S1, and the second switch S4 is connected in parallel with the second double-node pressure switch S2.

[0064] Among them, when the pressure transmitter detects that the pressure exceeds the first preset pressure and the pressure has not been reduced for a long time, the first dual-node pressure switch S1 fails and cannot be used. A pulse signal is sent to the first switch S3 through DCS to control the first relay and the second relay. When the pressure transmitter detects that the pressure is lower than the second preset pressure and has not changed for a long time, the second dual-node pressure switch S2 fails and cannot be used. A pulse signal is sent to the second switch S4 through DCS to control the third relay and the fourth relay.

[0065] Among them, there is a signal connection between DCS and the first switch S3. When the pressure transmitter detects that the steam pressure is greater than the first preset pressure, DCS sends a pulse signal to the first switch S3. For example, the pulse signal is 1s, and the first switch S3 is closed within 1s. When the pulse signal ends after 1s, the first switch S3 is automatically disconnected.

[0066] When the first switch S3 is closed, the coil KA1-S of the first relay and the coil KA2-S of the second relay are energized, so that the first normally open contact KA1-1 and the second normally open contact KA1-2 of the first relay and the first normally open contact KA2-1 and the second normally open contact KA2-2 of the second relay are closed. At this time, the second switch S4 is disconnected, the coil KA3-S of the third relay and the coil KA4-S of the fourth relay are de-energized, and the first normally closed contact KA3-1 of the third relay and the first normally closed contact KA4-1 of the fourth relay are closed, so that the coil YV of the solenoid valve connected to the second normally open contact KA1-2 of the first relay, the second normally open contact KA2-2 of the second relay, the first normally closed contact KA3-1 of the third relay and the first normally closed contact KA4-1 of the fourth relay is energized, so that the PCV valve opens.

[0067] Furthermore, when the first switch S3 is automatically disconnected, since the coil KA1-S of the first relay and the coil KA2-S of the second relay are energized within the time of the closing pulse signal of the first switch S3 within 1s, the first normally open contact KA1-1 of the first relay and the second normally open contact KA2-21 of the second relay are closed. At this time, the power supply VDD can provide electrical energy to the coil KA1-S of the first relay and the coil KA2-S of the second relay through the first normally open contact KA1-1 of the first relay and the second normally open contact KA2-2 of the second relay, so that the coil KA1-S of the first relay and the coil KA2-S of the second relay are energized, that is, the power supply VDD, the first normally open contact KA1-1 of the first relay, the first normally open contact KA2-1 of the second relay and the coil KA1-S of the first relay and the coil KA2-S of the second relay form a self-holding circuit. When the pulse signal ends, the power supply VDD continues to provide power to the coil KA1-S of the first relay and the coil KA2-S of the second relay, so that the coil KA1-S of the first relay and the coil KA2-S of the second relay continue to be energized, so that the solenoid valve coil YV is energized, so that the PCV valve opens to release pressure. The first normally open contact KA1-1 of the first relay and the first normally open contact KA2-1 of the second relay continue to be closed, and the first normally open contact KA1-1 of the first relay and the first normally open contact KA2-1 of the second relay form a self-holding circuit with the power supply VDD.

[0068] There is a signal connection between the DCS and the second switch S4. When the pressure transmitter detects that the steam pressure is less than the second preset pressure, the DCS sends a pulse signal to the second switch S4. Exemplarily, the pulse signal is 1s, and the second switch S4 is closed within 1s and opened within 1s.

[0069] When S4 is closed, the coil KA3-S of the third relay and the coil KA4-S of the fourth relay are energized, and the first normally closed contact KA3-1 of the third relay and the first normally closed contact KA4-1 of the fourth relay are disconnected. At this time, even if the second normally open contact KA1-2 of the first relay and the second normally open contact KA2-2 of the second relay are in a closed state due to the self-holding circuit, the coil YV of the solenoid valve will lose power, and the PCV valve will be closed.

[0070] When the pulse signal ends after 1s, the second switch S4 is disconnected, the coil KA3-S of the third relay and the coil KA4-S of the fourth relay are de-energized, and the first normally closed contact KA3-1 of the third relay and the first normally closed contact KA4-1 of the fourth relay are closed. At this time, the second normally open contact KA1-2 of the first relay and the second normally open contact KA2-2 of the second relay need to be disconnected, otherwise, the coil YV of the solenoid valve will be energized, so that the PCV valve opens. At this time, the coil YV of the solenoid valve needs to be in a de-energized state, so that the PCV valve closes. Therefore, the second normally open contact KA1-2 of the first relay and the second normally open contact KA2-2 of the second relay need to be disconnected.

[0071] At this time, the staff can manually de-energize the coil KA1-S of the first relay and the coil KA2-S of the second relay, for example, by setting a first manual button between the coil KA1-S of the first relay and the first normally open contact KA1-1 of the first relay, and setting a second manual button between the coil KA2-S of the second relay and the first normally open contact KA2-1 of the second relay.

[0072] Alternatively, a second normally closed contact of the third relay is set between the coil KA1-S of the first relay and the first normally open contact KA1-1 of the first relay, and a second normally closed contact of the fourth relay is set between the coil KA2-S of the second relay and the first normally open contact KA2-1 of the second relay. When the steam pressure gradually decreases to less than the second preset pressure, the coil KA3-S of the third relay and the coil KA4-S of the fourth relay are energized, and the second normally closed contact KA3-2 of the third relay and the second normally closed contact KA4-2 of the fourth relay are disconnected, thereby disconnecting the coil KA1-S of the first relay and the first normally open contact KA1-1 of the first relay, and disconnecting the coil KA2-S of the second relay and the first normally open contact KA2-1 of the second relay, thereby disconnecting the self-holding circuit.

[0073] Among them, by setting a self-holding loop, the DCS only needs to send a pulse signal once, and there is no need to continuously send a pulse signal to maintain the operating state of the first relay and the second relay. This can reduce the number and frequency of pulse signals and simplify the design and operation of the control system.

[0074] Alternatively, see Figure 2 The PCV valve control system also includes: an operating table, on which a third switch S5 and a fourth switch S6 are arranged, the third switch S5 is connected in parallel with the first switch S1, and the fourth switch S6 is connected in parallel with the second switch S2.

[0075] Among them, when the pressure exceeds the first preset pressure and the DCS sends a pulse signal, the pressure transmitter detects that the current pressure still exceeds the first preset pressure for a long time. At this time, the first double-node pressure switch S1 and the first switch S3 are both faulty. The staff controls the third switch S5 to close through the operating console, thereby controlling the first relay and the second relay. When the pressure is less than the second preset pressure and the DCS sends a pulse signal, the pressure transmitter detects that the current pressure is still lower than the second preset pressure for a long time. At this time, the second double-node pressure switch S2 and the second switch S4 are faulty. The staff controls the fourth switch S6 to close through the operating console, thereby controlling the third relay and the fourth relay.

[0076] Among them, when the pressure transmitter detects that the pressure is greater than the first preset pressure, the staff obtains the information that the PCV valve needs to be opened at the DCS, so that the staff closes the third switch S5 on the operating console. After the third switch S5 is closed, the coil KA1-S of the first relay and the coil KA2-S of the second relay are energized, so that the first normally open contact KA1-1 of the first relay is closed, the second normally open contact KA1-2 of the first relay is closed, the first normally open contact KA2-1 of the second relay coil is closed, and the second normally open contact KA2-2 of the second relay coil is closed. At this time, the coil YV of the solenoid valve is energized.

[0077] Among them, when the pressure transmitter detects that the pressure is lower than the second preset pressure, the staff obtains the information that the PCV valve needs to be closed at the DCS, so that the staff closes the fourth switch S6 at the operating console. After the fourth switch S6 is closed, the coil KA3-S of the third relay and the coil KA4-S of the fourth relay are energized, so that the first normally closed contact KA3-1 of the third relay is closed and the first normally closed contact KA4-1 of the fourth relay coil is closed. At this time, the coil YV of the solenoid valve is energized.

[0078] Alternatively, see Figure 3 The PCV valve control system also includes: a third indicator light L3, and the third indicator light L3 is connected to the power supply VDD.

[0079] Among them, the third indicator light L3 is connected to the power supply VDD. When the power supply VDD is turned on, the third indicator light L3 lights up, and other components can work normally at this time, which is used to remind the staff that the power supply VDD is currently turned on.

[0080] Optionally, the PCV valve control system further includes: a fuse BF, and the fuse BF is connected to the power supply VDD.

[0081] The power supply VDD includes a live wire VDD-L and a neutral wire VDD-N. The fuse BF is set on the live wire of the power supply VDD. When the circuit is overloaded or short-circuited, the fuse BF will quickly cut off the current to prevent overheating of the wires, fire or damage to the electrical appliances.

[0082] Finally, it should be noted that all contents not described in the technical solution of this application can be implemented using existing technologies. In addition, the above embodiments are only used to illustrate the technical solution of this application, rather than to limit it; although the application is described in detail with reference to the above embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the above embodiments, or replace some or all of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A PCV valve control system, characterized in that: include: a first double-node pressure switch, a second double-node pressure switch, a first relay, a third relay, and a solenoid valve; The first double-node pressure switch is a normally open switch, and the triggering pressure of the first double-node pressure switch is a first preset pressure; the second double-node pressure switch is a normally closed switch, and the triggering pressure of the second double-node pressure switch is a second preset pressure, and the first preset pressure is greater than the second preset pressure; One end of the first dual-node pressure switch is connected to a power source, the other end of the first dual-node pressure switch is connected to the coil of the first relay, and a first normally open contact of the first relay is connected in parallel with the first dual-node pressure switch; One end of the second double-node pressure switch is connected to a power supply, the other end of the second double-node pressure switch is connected to a coil of the third relay, a first normally closed contact of the third relay is connected in series with the coil of the solenoid valve and then connected to the power supply, and a second normally open contact of the first relay is connected in series with the coil of the solenoid valve; The solenoid valve is connected to the PCV valve.

2. The PCV valve control system according to claim 1, characterized in that: Also includes: The second relay and the fourth relay; The coil of the second relay is connected in parallel with the coil of the first relay, the first normally open contact of the second relay is connected in parallel with the first normally open contact of the first relay, and the second normally open contact of the second relay is connected in parallel with the second normally open contact of the first relay; The coil of the fourth relay is connected in parallel with the coil of the third relay, and the first normally closed contact of the fourth relay is connected in series with the first normally closed contact of the third relay.

3. The PCV valve control system according to claim 1 or 2, characterized in that: Also includes: The fifth relay, the first travel switch, and the first indicator light; The first travel switch is installed in the first position of the PCV valve. The first position is when the PCV valve is fully opened and the valve of the PCV valve can just squeeze the position of the first travel switch. The first travel switch is connected in series with the coil of the fifth relay and then connected to the power supply. The normally open contact of the fifth relay is connected in series with the first indicator light and then connected to the power supply.

4. The PCV valve control system according to claim 1 or 2, characterized in that: It also includes a sixth relay, a second travel switch, and a second indicator light; The second travel switch is installed in the second position of the PCV valve. The second position is when the PCV valve is fully closed and the valve of the PCV valve can just squeeze the position of the second travel switch. The second travel switch is connected in series with the coil of the sixth relay and then connected to the power supply. The normally open contact of the sixth relay is connected in series with the second indicator light and then connected to the power supply.

5. The PCV valve control system according to claim 1 or 2, characterized in that: Also includes: A DCS, a first switch, a second switch, and a pressure transmitter, wherein the DCS is connected to the pressure transmitter, the first switch and the second switch are both connected to the DCS, the first switch is connected in parallel to the first dual-node pressure switch, and the second switch is connected in parallel to the second dual-node pressure switch.

6. The PCV valve control system according to claim 5, characterized in that: Also includes: An operating table, on which a third switch and a fourth switch are arranged, wherein the third switch is connected in parallel with the first switch, and the fourth switch is connected in parallel with the second switch.

7. The PCV valve control system according to claim 1 or 2, characterized in that: Also includes: A third indicator light is connected to the power supply.

8. The PCV valve control system according to claim 1 or 2, characterized in that: Also includes: A fuse is connected to the power source.

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