Pulse acquisition circuit and controller for flow metering

Abstract

The application provides a pulse collection circuit and a controller for flow metering. The pulse collection circuit comprises a power supply circuit, an anti-interference circuit and a metering circuit, the power supply circuit is connected with the metering circuit and the anti-interference circuit respectively, and the anti-interference circuit is connected with the metering circuit. The anti-interference circuit is used for receiving a pulse signal collected by a flow meter and sending the pulse signal to the metering circuit, wherein the pulse signal comprises an active pulse signal and a passive pulse signal. The metering circuit is used for counting flow according to the pulse signal, and the power supply circuit is used for providing a bias voltage for the pulse signal input to the metering circuit and the anti-interference circuit. According to the application, the active pulse signal and the passive pulse signal collected by the flow meter can be received by the same pulse collection circuit, and then flow metering is performed according to the collected active pulse signal or passive pulse signal, so that the user can use more conveniently.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit, and particularly relates to a pulse collection circuit and a controller for flow measurement. BACKGROUND

[0002] The flow meter is matched with the controller, and can be used for measuring the quantity of fluid in a pipeline or an open channel, and is widely applied in multiple scenes. For example, the flow meter can be applied in a gas measurement scene, data is collected by a gas flow meter installed in a gas pipeline, and the controller measures the gas flow according to the collected data.

[0003] Taking the gas measurement scene as an example, in the prior art, the measurement of the gas flow is performed according to the pulse signal received by the pulse collection circuit of the controller. If the pulse signal is an active pulse signal, the measurement is performed according to the change of the pulse signal by the corresponding active pulse collection circuit. If the pulse signal is a passive pulse signal, the measurement is performed according to the change of the pulse signal by the corresponding passive pulse collection circuit.

[0004] However, the same pulse collection circuit in the prior art cannot simultaneously support the active pulse signal and the passive pulse signal, which brings inconvenience to the user. SUMMARY

[0005] The present application provides a pulse collection circuit and a flow meter for flow measurement, to solve the problem that the same pulse collection circuit in the prior art cannot support the active pulse signal and the passive pulse signal.

[0006] In a first aspect, the present application provides a pulse collection circuit for flow measurement, comprising:

[0007] a power supply circuit, an anti-interference circuit and a measurement circuit;

[0008] The power supply circuit is connected with the measurement circuit and the anti-interference circuit respectively, and the anti-interference circuit is connected with the measurement circuit.

[0009] The anti-interference circuit is used for receiving the pulse signal collected by the flow meter, and sending the pulse signal to the measurement circuit.

[0010] The measurement circuit is used for counting the flow according to the pulse signal.

[0011] The power supply circuit is used for providing a bias voltage for the pulse signal input to the measurement circuit and the anti-interference circuit.

[0012] Optionally, the power supply circuit comprises a first diode, a first pull-up resistor, a second pull-up resistor and a power supply.

[0013] The first diode cathode end is connected with the second pull-up resistor input end, the first diode anode end is connected with the power supply, and the power supply is also connected with the first pull-up resistor input end;

[0014] The second pull-up resistor output end is connected with the anti-interference circuit, and the first pull-up resistor output end is connected with the metering circuit.

[0015] Optionally, the anti-interference circuit comprises a first capacitor, a second diode and a third diode.

[0016] The first capacitor input end is connected with the second pull-up resistor output end and the second diode anode end respectively, the second diode cathode end is connected with the third diode anode end, the third diode cathode end is connected with the metering circuit, and the first capacitor output end is grounded.

[0017] Optionally, the first capacitor input end is used for receiving a pulse signal collected by the flow meter and filtering out a non-metering signal in the pulse signal.

[0018] Optionally, the metering circuit comprises a field effect transistor, a pull-down resistor, a current limiting resistor and a second capacitor.

[0019] The pull-down resistor input end is connected with the third diode cathode end and the field effect transistor gate end respectively, the field effect transistor drain is connected with the first pull-up resistor output end, and the pull-down resistor output end is grounded.

[0020] The current limiting resistor input end is connected between the field effect transistor drain and the first pull-up resistor output end.

[0021] The second capacitor input end is connected with the current limiting resistor output end, and the second capacitor output end is grounded with the field effect transistor source end respectively.

[0022] Optionally, the metering circuit further comprises a control unit.

[0023] The control unit is connected with the current limiting resistor output end.

[0024] The control unit is used for receiving a pulse signal output through the current limiting resistor.

[0025] Optionally, the pulse signal comprises an active pulse signal and a passive pulse signal, when the pulse signal is the active pulse signal, the control unit is specifically used for:

[0026] According to the output pulse signal, if the output pulse signal changes from a high pulse signal to a low pulse signal, and then changes from the low pulse signal to the high pulse signal, flow counting is performed.

[0027] Optionally, the pulse signal comprises an active pulse signal and a passive pulse signal, and when the pulse signal is the passive pulse signal, the control unit is specifically used for:

[0028] According to the output pulse signal, if the output pulse signal changes from a low pulse signal to a high pulse signal, and then changes from the high pulse signal to the low pulse signal, flow counting is performed.

[0029] Optionally, the field effect tube is an N-type field effect tube.

[0030] In a second aspect, the present application provides a controller comprising the pulse acquisition circuit for flow metering according to any one of the first aspect.

[0031] The present application provides a pulse acquisition circuit for flow metering and a controller. The circuit comprises a power supply circuit, an anti-interference circuit and a metering circuit. The power supply circuit is connected with the metering circuit and the anti-interference circuit respectively. The anti-interference circuit is connected with the metering circuit. The anti-interference circuit is used for receiving the pulse signal collected by the flow meter and sending the pulse signal to the metering circuit. The pulse signal comprises an active pulse signal and a passive pulse signal. The metering circuit is used for counting the flow according to the pulse signal. The power supply circuit is used for providing a bias voltage for the pulse signal input into the metering circuit and the anti-interference circuit. The pulse acquisition circuit of the present application can simultaneously compatible with the active pulse signal and the passive pulse signal, and then count according to the collected pulse signal, which is more convenient for users to use. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0033] Figure 1 A structure schematic diagram of a pulse acquisition circuit for flow metering provided by an embodiment of the present application;

[0034] Figure 2 A structure schematic diagram of a power supply circuit provided by an embodiment of the present application;

[0035] Figure 3 A structure schematic diagram of an anti-interference circuit provided by an embodiment of the present application;

[0036] Figure 4 A structure schematic diagram of a metering circuit provided by an embodiment of the present application;

[0037] Figure 5 A structure schematic diagram of a field effect tube provided by an embodiment of the present application;

[0038] Figure 6Another structure diagram of a pulse collection circuit for flow metering provided by an embodiment of the present application.

[0039] The specific embodiments of the present application have been shown through the above-described drawings, and will be described in more detail hereinafter. These drawings and the written description are not intended to restrict the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0040] The exemplary embodiments will be described in detail herein with reference to the attached drawings. In the following description, the same numbers are used to indicate the same or similar components. The embodiments described in the following exemplary embodiments are not meant to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present application as detailed in the appended claims.

[0041] In the description of the embodiments of the present application, the terms indicating the direction or position relationship of the terms "inner", "outer" and the like are based on the direction or position relationship shown in the drawings, which is merely for the convenience of description, and does not indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0042] In addition, it should be further pointed out that, in the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0043] The flow meter is used in conjunction with the controller to measure the flow of fluid in the pipeline (the volume of fluid passing through per unit time), and with the development of society and the progress of technology, it is widely used in many fields, for example, it can be applied to industrial production, household use, environmental protection, transportation, etc.

[0044] The present application takes the gas measurement scene as an example. At present, the flow collection of industrial and commercial gas meters is carried out by flow meters.

[0045] One method is that the flow meter collects flow data, and sends the collected flow data to the controller, and the controller performs metering according to the collected data. Another method is that the flow meter collects pulse signals, and sends the collected pulse signals to the controller, and the controller performs metering according to the collected pulse signals. The connection between the flow meter and the controller can be achieved through a 485 communication interface, a 422 communication interface, a 232 communication interface, etc.

[0046] When using pulse collection, the collected signals are generally divided into two types: active pulse signals and passive pulse signals.

[0047] The active pulse signal itself outputs a certain level of pulse signal, generally 3V-5V. After the controller receives the active pulse signal, it identifies the high and low level changes, and completes metering according to the preset level logic. The passive pulse signal itself does not output a level, and its type can be divided into two types: electronic switch type and relay type. Their common feature is that the output signal presents two impedance states of high resistance and low resistance, but the specific output level value is determined by the external power supply. Correspondingly, after the controller receives the passive pulse signal, it identifies the high and low level changes, and completes metering according to the preset level logic.

[0048] However, in the prior art, the pulse collection circuit of the controller uses two circuits corresponding to active pulse signals and passive pulse signals, respectively. If the pulse signal collected by the flow meter is an active pulse signal, metering is performed according to the change of the pulse signal through the corresponding active pulse collection circuit. If the collected pulse signal is a passive pulse signal, metering is performed according to the change of the pulse signal through the corresponding passive pulse collection circuit. These two pulse collection circuits are independent of each other and cannot be compatible, and the types of each circuit are diverse, which brings inconvenience to users. In addition, the existing pulse collection circuit also contains devices such as boost / buck chips, optocouplers, and operational amplifiers, which can achieve the stability of the circuit, but the circuit is complex and the cost is high.

[0049] Therefore, in order to solve the above technical problems of the prior art, the application provides a pulse acquisition circuit and a controller for flow metering. The pulse acquisition circuit comprises a power supply circuit, an anti-interference circuit and a metering circuit. The power supply circuit is connected with the metering circuit and the anti-interference circuit respectively, and the anti-interference circuit is connected with the metering circuit. The anti-interference circuit is used for receiving a pulse signal collected by a flow meter and sending the pulse signal to the metering circuit. The pulse signal comprises an active pulse signal and a passive pulse signal. The metering circuit is used for counting flow according to the pulse signal. The power supply circuit is used for providing a bias voltage for the pulse signal input to the metering circuit and the anti-interference circuit. The application can receive the active pulse signal and the passive pulse signal collected by the flow meter through the same pulse acquisition circuit, and then count flow according to the collected active pulse signal or passive pulse signal, so that the user can use more conveniently.

[0050] The technical solutions of the application and how the application solves the above technical problems will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes can not be described again in some embodiments. The embodiments of the application will be described below with reference to the drawings.

[0051] Figure 1 A structure diagram of a pulse acquisition circuit for flow metering provided by an embodiment of the application is shown in FIG. 1. The pulse acquisition circuit provided by the application comprises a power supply circuit 11, an anti-interference circuit 12 and a metering circuit 13. Figure 1

[0052] The electronic device or apparatus comprising the pulse acquisition circuit described above in the application can be a controller, etc. The controller acquires the pulse signal collected by the flow meter by communicating with the flow meter. The pulse signal comprises an active pulse signal and a passive pulse signal.

[0053] The active pulse signal means that the signal node can be directly connected to a power supply. The passive pulse signal means that the signal node is connected to various switching electronic elements or relay electronic elements, such as limit switches, travel switches, relays, etc.

[0054] The flow meter in the application can comprise various types, such as a mass flow meter, a thermal mass flow meter, an ultrasonic flow meter, a vortex flow meter, a differential pressure flow meter, an orifice plate flow meter, etc. It can be understood that the types of flow meters listed in the application are only used for illustration and do not limit the application. The actual form of the flow meter and the controller is not limited.

[0055] The power supply circuit 11 is connected with the metering circuit 13 and the anti-interference circuit 12 respectively, and the anti-interference circuit 12 is connected with the metering circuit 13. ​

[0056] The anti-interference circuit 12 is configured to receive the pulse signal collected by the flow meter and send the pulse signal to the metering circuit 13.

[0057] For example, in a vortex flow meter installed in a fluid pipeline, within a certain flow range, the fluid flow drives the rotation of the turbine, and the rotation speed of the turbine can be converted into a pulse signal output.

[0058] For example, in an eddy current flow meter installed in a fluid pipeline, the change in frequency of the force on the vortex generator and the change in frequency of the flow near the vortex generator are detected by the internal installation of a thermal sensor, a photoelectric sensor, etc. Detection element, according to the detection result, it is converted into a pulse signal output.

[0059] In this application, fluid refers to a flowing substance, which is a general term for liquids and gases, and has the characteristics of flowing.

[0060] After the flow meter collects the pulse signal, it is sent to the anti-interference circuit 12 of the controller. After the anti-interference circuit 12 receives the pulse signal, it filters out the non-metering signal in the pulse signal, enhances the anti-interference performance of the pulse collection circuit by filtering out part of the noise signal, and sends the pulse signal after filtering out the non-metering signal to the metering circuit 13.

[0061] The metering circuit 13 is configured to count the flow according to the pulse signal.

[0062] One possible implementation is that after the metering circuit 13 receives the pulse signal after filtering out the non-metering signal, according to the high and low level change of the pulse signal, the metering is completed according to the preset level logic.

[0063] It should be noted that according to the different received pulse signals, that is, according to whether it is an active pulse signal or a passive pulse signal, the corresponding level logic is correspondingly selected.

[0064] The power supply circuit 11 is configured to provide a bias voltage for the pulse signal input to the metering circuit 13 and the anti-interference circuit 12, so that the pulse signal has a stable level when input to the metering circuit 13 and the anti-interference circuit 12. The power supply circuit 11 can also provide power supply for the metering circuit 13 and the anti-interference circuit 12.

[0065] In the above embodiment of the present application, the pulse acquisition circuit for flow metering comprises a power supply circuit 11, an anti-interference circuit 12 and a metering circuit 13, the power supply circuit 11 is connected with the metering circuit 13 and the anti-interference circuit 12 respectively, and the anti-interference circuit 12 is connected with the metering circuit 13. The anti-interference circuit 12 is used for receiving the pulse signal collected by the flow meter and sending the pulse signal to the metering circuit 13, wherein the pulse signal comprises an active pulse signal and a passive pulse signal. The metering circuit 13 is used for counting the flow according to the pulse signal, and the power supply circuit 11 is used for providing a bias voltage for the pulse signal input to the metering circuit 13 and the anti-interference circuit 12. The pulse acquisition circuit in the embodiment can simultaneously compatible with the active pulse signal and the passive pulse signal, and then count according to the collected pulse signal, so that the user can use more conveniently.

[0066] Further, on the basis of the above embodiment, the structure and composition of the power supply circuit 11, the anti-interference circuit 12 and the metering circuit 13 are described in detail through the following embodiments.

[0067] Figure 2 A structure schematic diagram of the power supply circuit 11 provided in the embodiment of the present application is shown in FIG. 1, which comprises a first diode 111, a first pull-up resistor 112, a second pull-up resistor 113 and a power supply 114. Figure 2

[0068] The cathode end of the first diode 111 is connected with the input end of the second pull-up resistor 113, the anode end of the first diode 111 is connected with the power supply 114, and the power supply 114 is also connected with the input end of the first pull-up resistor 112.

[0069] The output end of the second pull-up resistor 113 is connected with the anti-interference circuit 12, and the output end of the first pull-up resistor 112 is connected with the metering circuit 13.

[0070] In a possible implementation, the pull-up resistor in the present application can be a fixed resistor or a variable resistor.

[0071] Since the first pull-up resistor 112 also bears most of the current when the field effect transistor 131 is turned on, in order to reduce the power consumption of the circuit and ensure the safety of the device, the resistance value can be preferably selected in the order of MΩ. Since the second pull-up resistor 113 bears the function of a voltage dividing resistor, accordingly, in order to reduce the power consumption of the circuit, the resistance value of the second pull-up resistor 113 can also be preferably selected in the order of MΩ.

[0072] In a possible implementation, the power supply 114 can be a controllable power supply, and the voltage regulation function is realized by controlling the power supply voltage. By using the controllable power supply, the power consumption of the controller during the non-pulse signal acquisition period can be reduced.

[0073] ​In a possible implementation, the first diode 111 can be a reverse prevention diode, for example, 1N4148, which has a small leakage current and can realize protection of the power supply end.

[0074] It can be understood that the first diode 111 can also be of other types, which are not limited in the present application.

[0075] Figure 3 A structural schematic diagram of an anti-interference circuit 12 provided in the embodiment of the present application is shown in FIG. 2, which includes a first capacitor 121, a second diode 122 and a third diode 123. Figure 3

[0076] The input end of the first capacitor 121 is connected to the output end of the second pull-up resistor 113 and the anode end of the second diode 122, the cathode end of the second diode 122 is connected to the anode end of the third diode 123, the cathode end of the third diode 123 is connected to the metering circuit 13, and the output end of the first capacitor 121 is grounded.

[0077] In a possible implementation, the second diode 122 and the third diode 123 are used to increase the on voltage of the metering circuit 13.

[0078] The forward on current of the metering circuit 13 is large, and the use of two diodes can increase the voltage, thereby reducing the false on of the field effect transistor 131, and further increasing the accuracy of metering. The second diode 122 and the third diode 123 can be, for example, 1N4148 or 1N4007.

[0079] It can be understood that the type of diode is not limited in the present application, and can be selected according to actual conditions.

[0080] In addition, in the present embodiment, the second diode 122 and the third diode 123 can also be deleted, but in order to avoid the false on of the field effect transistor 131, the preset voltage at which the field effect transistor 131 is turned on needs to be set to be larger.

[0081] In a possible implementation, the input end of the first capacitor 121 is used to receive a pulse signal collected by a flow meter, and non-metering signals in the pulse signal are filtered out.

[0082] Figure 4 A structural schematic diagram of a metering circuit 13 provided in the embodiment of the present application is shown in FIG. 3, which includes a field effect transistor 131, a pull-down resistor 132, a current limiting resistor 133 and a second capacitor 134. Figure 4

[0083] ​​The input end of the pull-down resistor 132 is connected with the cathode end of the third diode 123 and the gate end of the field effect transistor 131 respectively, the drain end of the field effect transistor 131 is connected with the output end of the first pull-up resistor 112, and the output end of the pull-down resistor 132 is grounded.

[0084] The input end of the current-limiting resistor 133 is connected between the drain end of the field effect transistor 131 and the output end of the first pull-up resistor 112.

[0085] The input end of the second capacitor 134 is connected with the output end of the current-limiting resistor 133, and the output end of the second capacitor 134 is grounded with the source end of the field effect transistor 131 respectively.

[0086] In a possible implementation, when the resistance value of the pull-down resistor 132 is selected, in order to reduce the power consumption of the circuit, the resistance value can be selected in the order of MΩ.

[0087] In a possible implementation, in order to ensure the rationality of the rising edge and the falling edge of the pulse signal in time, the ratio between the current-limiting resistor 133 and the second capacitor 134 can be equal to 1 / 2πf, wherein f represents the frequency, and the frequency deviation can be within the range of 10 kHz. The resistance value of the current-limiting resistor 133 can be selected in the order of KΩ, the second capacitor 134 can be selected in the range of 100 pF to 1 uF, and the capacitance value of the second capacitor 134 is equal to that of the first capacitor 121.

[0088] It can be understood that the data range described above is not limited in the application, and can be selected according to actual conditions.

[0089] In a possible implementation, the field effect transistor 131 can be an N-type field effect transistor (N-Metal-Oxide-Semiconductor, NMOS).

[0090] The NMOS is a commonly used switching device in the control circuit, and according to the size relationship between the voltage received by the receiving end of the NMOS and the preset voltage value, the conduction and the closing of the NMOS can be controlled.

[0091] In order to ensure that the NMOS is completely turned on, the conduction voltage should not be too large, for example, it can be lower than 1.4V.

[0092] The structure of the field effect transistor 131 is shown in Figure 5 , and Figure 5 is a structure diagram of the field effect transistor 131 provided by the embodiment of the application, which includes a gate end G, a drain end D and a source end S.

[0093] In use, the field effect transistor 131 is usually provided with a preset voltage VG, and the field effect transistor 131 is turned on only when the voltage VB received by the gate end of the field effect transistor 131 is greater than the preset voltage VG. Therefore, the preset voltage can ensure that the field effect transistor 131 is in a stable state, and prevent it from being frequently turned on or off due to the influence of other signals.

[0094] It should be noted that the specific value of the preset voltage VG is not limited in the present application, and can be set according to the actual application.

[0095] In a possible implementation, the metering circuit 13 can further include a control unit 135.

[0096] The control unit 135 is connected to the output end of the current limiting resistor 133, and is used to receive the pulse signal output by the current limiting resistor 133.

[0097] The current limiting resistor 133 can prevent the control unit 135 from being damaged by a large current, and the second capacitor 134 is a filtering circuit, which can enable the output pulse signal to be stably transmitted to the control unit 135.

[0098] The control unit 135 can also be used for selection of the resistance value of the current limiting resistor 133.

[0099] In a possible implementation, the resistance value of the current limiting resistor 133 can be determined according to the maximum current value that the control unit 135 can receive and the frequency of the output pulse signal, i.e., resistance value < power supply / maximum current.

[0100] In the above embodiments of the present application, the structural components of the power supply circuit 11 include the first diode 111, the first pull-up resistor 112, the second pull-up resistor 113 and the power supply 114, the structural components of the anti-interference circuit 12 include the first capacitor 121, the second diode 122 and the third diode 123, and the structure of the metering circuit 13 includes the field effect transistor 131, the pull-down resistor 132, the current limiting resistor 133 and the second capacitor 134. Through the above structure, the present embodiment can simultaneously meter the active pulse signal or the passive pulse signal collected, so that the user can use more conveniently. Moreover, the signal collection circuit of the present embodiment has a simple structure, a small number of device types and low power consumption, and can greatly improve the service life and reduce the cost.

[0101] Furthermore, in order to facilitate understanding of the present application, the pulse collection circuit is how to meter the flow is explained through the following specific examples on the basis of the above embodiments.

[0102] Figure 6 Another structure diagram of the pulse collection circuit for flow metering provided by the embodiments of the present application is shown in FIG. 5. Figure 6 As shown in FIG. 5.

[0103] Example 1,

[0104] Assume Figure 6 If the pulse signal collected by the flow meter is an active pulse signal, the control unit 135 is low active, which means that when the anti-interference circuit 12 receives the active pulse signal, the control unit 135 receives a low pulse signal.

[0105] First, adjust the resistance value of the second resistor in the power supply circuit 11 and the current limiting resistor 133 in the metering circuit 13, so that the voltage division on the current limiting resistor 133, i.e. the gate voltage VB of the NMOS transistor, is less than the preset voltage value VG, thereby ensuring that when the active pulse signal is not transmitted to the NMOS transistor, the NMOS transistor is in a closed state.

[0106] Alternatively, the adjustment of the second resistor and the current limiting resistor 133 can be to replace the resistor device with a corresponding resistance value, or if the second resistor and the current limiting resistor 133 are adjustment resistors, adjust them to their corresponding resistance values.

[0107] When the anti-interference circuit 12 does not receive the active pulse signal sent by the flow meter, the voltage VA at point A is less than 3V, where the active signal itself outputs a certain level of pulse signal, generally 3V-5V. And the voltage VB at point B is less than the preset voltage value VG, at this time, the NMOS transistor is in a closed state. However, due to the presence of the first pull-up resistor 112, the level VD output by point D is high, and therefore the control unit 135 receives a high pulse signal.

[0108] When the anti-interference circuit 12 receives the active pulse signal sent by the flow meter, the voltage VA at point A is raised to 3V~5V, at this time, VA is greater than VB, and VA VB>1.4V, 1.4V is because the second diode 122 and the third diode 123 raise the voltage, and in an ideal case, one diode raises 0.7V, so two diodes raise 1.4V. It can be understood that the present application does not limit the voltage raising value of each diode, which is related to the type of diode, and the present application is only used for example. Because the voltage VB at point B is raised by two diodes, the current VB is greater than the preset voltage value VG at this time, and the NMOS transistor is in a conducting state. Since the NMOS transistor is conducting, the source is grounded, and therefore the voltage at point C is 0 due to the grounding of the conducting state, and thus the voltage VD at point D is low at this time. The level VD output by point D is converted from high to low, and the level state is reversed, and therefore the control unit 135 receives a low pulse signal.

[0109] When the active pulse signal transmission ends, the voltage VA at point A returns to the original voltage, i.e., less than 3V, and the voltage VB at point B also returns to the original state. At this time, VB is less than the preset voltage VG, and the NMOS transistor is in the off state again. Similarly, due to the presence of the first pull-up resistor 112, the level VD output by the D point is converted from low to high, and thus the control unit 135 receives a high pulse signal.

[0110] In summary, according to the output pulse signal, if the output pulse signal changes from a high pulse signal to a low pulse signal and then changes from a low pulse signal to a high pulse signal, the control unit 135 performs flow counting.

[0111] Example 2,

[0112] Suppose Figure 6 If the pulse signal collected by the flow meter is a passive pulse signal, the control unit 135 is high. High active means that when the anti-interference circuit 12 receives a passive pulse signal, the control unit 135 receives a high pulse signal.

[0113] First, adjust the resistance values of the second resistor in the power supply circuit 11 and the current limiting resistor 133 in the metering circuit 13, so that the voltage division on the current limiting resistor 133, i.e., the gate voltage VB of the NMOS transistor, is greater than the preset voltage VG, thereby ensuring that when the passive pulse signal is not transmitted to the NMOS transistor, the NMOS transistor is in the on state.

[0114] Alternatively, the second resistor and the current limiting resistor 133 can be replaced with resistor devices with corresponding resistance values, or if the second resistor and the current limiting resistor 133 are adjustable resistors, they can be adjusted to their corresponding resistance values.

[0115] When the anti-interference circuit 12 does not receive the passive pulse signal sent by the flow meter, the voltage VA at point A is less than 3V. And VA VB>1.4V, 1.4V is because the second diode 122 and the third diode 123 have lifted the voltage. Ideally, one diode lifts 0.7V, and two diodes lift 1.4V. It can be understood that the application does not limit the voltage lifting value of each diode, which is related to the type of diode, and the application is only used for illustration. Since the voltage at point B is lifted by two diodes, the current VB is greater than the preset voltage VG at this time, and the NMOS transistor is in the on state. Since the NMOS transistor is on, the source is grounded, and thus the voltage at point C is 0 due to the on-state grounding, and thus the voltage VD at point D is low, and thus the control unit 135 receives a low pulse signal.

[0116] When the anti-interference circuit 12 receives the passive pulse signal sent by the flow meter, the voltage VA at point A is pulled down to 0, and at this time, VA VB<1.4V, the second diode 122 and the third diode 123 are not turned on, the voltage VB of the point B is less than the preset voltage value VG, at this time, the NMOS tube is in the off state. However, due to the existence of the first pull-up resistor 112, the level VD output by the point D is converted from a low level to a high level, completing the level state flip, and therefore the control unit 135 receives a high pulse signal.

[0117] When the passive pulse signal transmission ends, the voltage VA of the point A returns to the original voltage, i.e., less than 3V, and the voltage VB of the point B also returns to the original state, at this time, VB is greater than the preset voltage value VG, and the NMOS tube is again in the on state. Similarly, due to the on state of the NMOS tube, the source is grounded, and therefore the voltage of the point C becomes 0 due to the on state of the ground, and therefore the voltage VD of the point D becomes a low level, and therefore the control unit 135 receives a low pulse signal.

[0118] In summary, according to the output pulse signal, if the output pulse signal changes from a low pulse signal to a high pulse signal, and then changes from a high pulse signal to a low pulse signal, the control unit 135 performs flow counting.

[0119] In the above embodiments of the present application, through the pulse acquisition circuit of the present application, both active pulse signals and passive pulse signals can be acquired for metering, and the user can use it more conveniently.

[0120] The present application also provides a controller comprising the pulse acquisition circuit for flow metering of any of the above embodiments.

[0121] Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the present application cover any and all variations of the application that come within the scope of the general inventive concepts described herein and including all modifications, equivalents, and alternatives falling within the scope of the present application. The specification and examples are illustrative only and not restrictive of the present application. The true scope and spirit of the application is indicated by the following claims.

[0122] It should be understood that the present application is not limited to the precise construction that has been described above and illustrated in the accompanying drawings and that various modifications and changes can be made by those skilled in the art without departing from the scope of the present application. The scope of the present application is limited only by the appended claims.

Claims

1. A pulse acquisition circuit for flow metering, characterized in that, include: Power supply circuit, anti-interference circuit, and metering circuit; The power supply circuit is connected to the metering circuit and the anti-interference circuit respectively, and the anti-interference circuit is connected to the metering circuit. The anti-interference circuit is used to receive the pulse signal collected by the flow meter and send the pulse signal to the metering circuit; The metering circuit is used to count the flow rate based on the pulse signal; The power supply circuit is used to provide a bias voltage for the pulse signals input to the metering circuit and the anti-interference circuit; The power supply circuit includes: a first diode, a first pull-up resistor, a second pull-up resistor, and a power supply; The cathode of the first diode is connected to the input terminal of the second pull-up resistor, and the anode of the first diode is connected to the power supply. The power supply is also connected to the input terminal of the first pull-up resistor. The output terminal of the second pull-up resistor is connected to the anti-interference circuit, and the output terminal of the first pull-up resistor is connected to the metering circuit. The anti-interference circuit includes: a first capacitor, a second diode, and a third diode; The input terminal of the first capacitor is connected to the output terminal of the second pull-up resistor and the anode of the second diode, the cathode of the second diode is connected to the anode of the third diode, the cathode of the third diode is connected to the metering circuit, and the output terminal of the first capacitor is grounded. The first capacitor input terminal is used to receive the pulse signal collected by the flow meter and filter out the non-metering signal in the pulse signal; The metering circuit includes: a field-effect transistor, a pull-down resistor, a current-limiting resistor, and a second capacitor; The input terminal of the pull-down resistor is connected to the cathode of the third diode and the gate terminal of the field-effect transistor, respectively. The drain of the field-effect transistor is connected to the output terminal of the first pull-up resistor, and the output terminal of the pull-down resistor is grounded. The input terminal of the current-limiting resistor is connected between the drain of the field-effect transistor and the output terminal of the first pull-up resistor. The input terminal of the second capacitor is connected to the output terminal of the current-limiting resistor, and the output terminal of the second capacitor is grounded to the source terminal of the field-effect transistor. The metering circuit also includes: a control unit; The control unit is connected to the output terminal of the current-limiting resistor; The control unit is used to receive pulse signals output through the current-limiting resistor, the pulse signals including active pulse signals and passive pulse signals.

2. The pulse acquisition circuit for flow measurement according to claim 1, characterized in that, When the pulse signal is the active pulse signal, the control unit is specifically used for: Based on the output pulse signal, if the output pulse signal changes from a high pulse signal to a low pulse signal, and then changes from a low pulse signal to a high pulse signal, then flow counting is performed.

3. The pulse acquisition circuit for flow measurement according to claim 2, characterized in that, The pulse signal includes active pulse signals and passive pulse signals. When the pulse signal is a passive pulse signal, the control unit is specifically used for: Based on the output pulse signal, if the output pulse signal changes from a low pulse signal to a high pulse signal, and then changes from a high pulse signal to a low pulse signal, then flow counting is performed.

4. The pulse acquisition circuit for flow metering according to claim 2 or 3, characterized in that, The field-effect transistor is an N-type field-effect transistor.

5. A controller, characterized in that, include: The pulse acquisition circuit for flow measurement as described in any one of claims 1-4.

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