CN207795498U - A kind of constant pressure and flow pump - Google Patents

Abstract

The utility model provides a constant pressure and constant flow pump different from the prior art solution, which can realize stable control of pressure and flow. Two sets of liquid output devices operate alternately, which can realize continuous output of pressure liquid; when one set of liquid output device is in operation, the pressure of the other set of liquid output device is controlled by the controller to keep equal to the pressure liquid, and the two sets of liquid output When the device is switched, there is no pressure difference, thus ensuring the stability of the overall output pressure.

Description

A constant pressure and constant flow pump

technical field

The utility model relates to the field of test equipment, in particular to a constant pressure and constant flow pump.

Background technique

In scientific experiments such as geology and oil and gas development, the constant pressure and constant flow pump is an important component, such as 201610553336.X "Dynamic Damage Evaluation Device and Method for Shale Base Block Based on Liquid Pressure Pulse", 201710099944.2 "A Kind of Ultrasonic Action In "Shale Permeability Testing Device and Method Based on Liquid Pressure Pulse", a constant pressure and constant flow pump is used to drive the test liquid to circulate stably. In 201710429869.1, a constant pressure is used in "A Simulation Method and Device for the Expansion of Hydraulic Fracturing Fractures in a Plane". The constant flow pump pumps out the fluid to fracture the rock sample. The Chinese invention patent application with application number 201510094375.3 proposes a "constant flow pump device", which can realize the function of constant pressure and constant flow.

Contents of the invention

The technical problem to be solved by the utility model is to provide a constant pressure and constant flow pump which is different from the existing technical solutions, and can realize stable control of pressure and flow.

The technical scheme of the utility model is: a constant pressure constant flow pump, including a first liquid output device, the first liquid output device includes: a plunger cylinder, a plunger, a screw, a nut, a motor, and the plunger is installed on In the plunger cylinder, the nut is connected to the plunger, the screw is matched with the nut, and the motor drives the screw to rotate, so that the nut drives the plunger to reciprocate in the plunger cylinder. When the plunger is pushed out, the liquid is pushed out from the plunger cylinder. , when the plunger is retracted, the liquid is sucked into the plunger cylinder; it is characterized in that the first liquid output device also includes a pressure sensor and a rotary encoder, and the pressure sensor is arranged on the output pipeline of the plunger cylinder for Detecting the pressure of the liquid output by the plunger cylinder, the rotary encoder is installed on the motor to detect the rotation angle of the motor; it also includes a second liquid output device, a controller, a first on-off valve, a second on-off valve, The third on-off valve and the fourth on-off valve; the inlet of the first on-off valve is connected to the liquid output port of the plunger cylinder of the first liquid output device, and the first on-off valve is connected to the liquid output port of the plunger cylinder of the first liquid output device The pipeline between them is provided with a bypass, the second switch valve is set on the bypass, the outlet of the second switch valve communicates with the liquid output port of the plunger cylinder of the first liquid output device, and the inlet of the second switch valve communicates with the liquid supply tank connected; the composition of the second liquid output device is the same as that of the first liquid output device, the inlet of the third switch valve is connected to the plunger cylinder liquid output port of the second liquid output device, and the third switch valve is connected to the second liquid output device. The pipeline between the liquid output port of the plunger cylinder of the liquid output device is provided with a bypass, the fourth on-off valve is arranged on the bypass, and the outlet of the fourth on-off valve communicates with the liquid output port of the plunger cylinder of the second liquid output device. The inlet of the fourth on-off valve communicates with the liquid supply tank; the outlets of the first on-off valve and the third on-off valve communicate with the pump liquid outlet. The pressure sensors of the first and second liquid output devices and the signal output terminals of the rotary encoders are all connected to the controller. The first, second, third and fourth on-off valves are all electronically controlled. 3. The control ends of the fourth on-off valve are all connected to the controller, and the controller controls the on-off of the first, second, third, and fourth on-off valves.

Its working state is the cycle operation of the following steps (1) and (2):

(1) The controller controls the opening of the first switching valve and the closing of the second switching valve, the plunger of the first liquid output device is pushed out, and the pressure liquid is supplied to the outside through the first switching valve and the pump liquid outlet; the controller outputs the liquid through the first liquid The pressure sensor of the device obtains the output liquid pressure value of the plunger cylinder of the first liquid output device, the controller obtains the motor speed through the rotary encoder of the first liquid output device, and then converts it into the pressure liquid flow value, and the controller converts the pressure value, flow rate The value is compared with the set value, and the steering and rotation speed of the motor of the first liquid output device are controlled by the comparison result, thereby realizing the pressure and flow control of the pressure liquid; at the same time, the controller controls the third switch valve to close and the fourth switch The valve is opened, the plunger of the second liquid output device is retracted, and the liquid is drawn from the liquid supply tank through the fourth on-off valve, and the fourth on-off valve is closed after the pump is full; the pressure value is compared with the set value by the controller, and the As a result, the steering and rotating speed of the motor of the second liquid output device are controlled, and the output pressure of the plunger cylinder of the second liquid output device is equal to the set value and the output pressure of the plunger cylinder of the first liquid output device when waiting for output; When the plunger of the first liquid output device reaches the end of the stroke, the controller will control the first on-off valve to close and the third on-off valve to open, and switch to the second liquid output device to output pressure liquid;

(2) The plunger of the second liquid output device is pushed out, and the pressure liquid is supplied to the outside world through the third switch valve and the pump liquid outlet; the controller passes the pressure sensor of the second liquid output device, the second rotary encoder of the second liquid output device The liquid obtains the liquid supply pressure and flow information, compares it with the set value, controls the steering and rotation speed of the motor of the second liquid output device through the comparison result, and then realizes the pressure and flow control of the pressure liquid; at the same time, the controller controls the first The on-off valve is closed, the second on-off valve is opened, the plunger of the first liquid output device is retracted, and the liquid is drawn from the liquid supply tank through the second on-off valve, and the second on-off valve is closed after the pumping is full; Compared with the set value, the steering and rotation speed of the motor of the first liquid output device are controlled by the comparison result, and the plunger cylinder of the first liquid output device outputs the liquid pressure and the set value when waiting for output, and the column of the second liquid output device The output pressure of the plug cylinder is equal; when the plunger of the second liquid output device reaches the end of the stroke, the controller will control the opening of the first switching valve and the closing of the third switching valve, and switch to the output pressure of the first liquid output device liquid;

Two sets of liquid output devices operate alternately, which can realize continuous output of pressure liquid; when one set of liquid output device is in operation, the pressure of the other set of liquid output device is controlled by the controller to keep equal to the pressure liquid, and the two sets of liquid output When the device is switched, there is no pressure difference, thus ensuring the stability of the overall output pressure.

The type of motor is a servo motor. Servo motor is used, which has high control precision and can better realize the adjustment of pressure and flow.

The type of controller is PLC. In the field of automatic control, the control method of the motor has been mature, and there are many control methods to realize the control of the motor, such as PID control, etc., and the PLC control method is adopted, which is simple and easy.

The type of the screw is a ball screw. The ball screw has small resistance, high motion precision and small transmission loss.

The motor and the screw rod are connected through a reducer. Through the reducer as an intermediary, the motor can be installed in multiple directions, which is more convenient.

Description of drawings

Fig. 1 is a schematic diagram of a constant pressure and constant flow pump of the present invention.

Fig. 2 is a structural schematic diagram of an embodiment of the first or second liquid output device.

Detailed ways

Embodiment 1.

An embodiment of a constant pressure and constant flow pump of the present invention is described in conjunction with accompanying drawing 1 .

As shown in Figure 1, the constant pressure and constant flow pump includes: a controller 1, a first liquid output device 2, a first on-off valve 3, a second on-off valve 4, a pump liquid outlet 5, a liquid supply tank 6, and a third on-off valve 7. The fourth switch valve 8, the second liquid output device 9; the first liquid output device includes: pressure sensor 11, plunger cylinder 12, plunger 13, nut 14, screw rod 15, reducer 16, motor 17, rotary The encoder 18 and the plunger 13 are installed in the plunger cylinder 12, the plunger 13 is connected with the nut 14, the nut 14 cooperates with the screw rod 15, the screw rod 15 and the nut 14 form a nut pair, and the rotation action of the screw rod 15 is converted into The linear movement of the nut 14 drives the plunger 13 to reciprocate in the plunger cylinder 12 through the nut 14, the power output end of the motor 17 is connected with the power input end of the reducer 16, the power output end of the reducer 16 is connected with the screw rod 15, and the power Through the motor 17, the reducer 16, the screw rod 15, the nut 14, and the plunger 13, it is finally converted into the pressure liquid output in the plunger cylinder 12, and the flow direction of the pressure liquid in the plunger cylinder 12 can be controlled by controlling the motor 17. Pressure, flow rate, when the motor 17 rotates forward, the plunger 13 is pushed forward, forcing the liquid to flow out of the plunger cylinder 12, forcing the liquid pressure to rise, and when the motor 17 speeds up, the flow rate of the output liquid also increases; when the motor 17 reverses, The plunger 13 is pulled back to force the liquid to flow into the plunger cylinder 12; the signal output terminals of the pressure sensor 11 and the rotary encoder 18 are all connected with the controller 1, and the pressure sensor 11 detects the pressure of the output liquid of the plunger cylinder 12, and It is transmitted to the controller 1, and the rotary encoder 18 is installed on the motor 17, and the rotation angle data of the motor 17 is transmitted to the controller 1, and the controller 1 converts the rotational speed of the motor 17 and the flow rate of the liquid output by the plunger cylinder 12; The composition of the second liquid output device 9 is the same as that of the first liquid output device 2. For ease of comparison, the same parts as the first liquid output device 2 in the second liquid output device 9 are all added with "second" at the front, and the number of its label is Tens digit changed from "1" to "2".

The second liquid output device 9 includes: a second pressure sensor 21, a second plunger cylinder 22, a second plunger 23, a second nut 24, a second screw mandrel 25, a second speed reducer 26, a second motor 27, a second Two rotary encoders 28, the second plunger 23 is installed in the second plunger cylinder 22, the second plunger 23 is connected with the second nut 24, the second nut 24 cooperates with the second screw mandrel 25, and the second screw mandrel 25 , The second nut 24 forms a nut pair, which converts the rotation of the second screw mandrel 25 into the linear motion of the second nut 24, and drives the second plunger 23 to reciprocate in the second plunger cylinder 22 through the second nut 24, The power output end of the second electric motor 27 is connected with the power input end of the second speed reducer 26, and the power output end of the second speed reducer 26 is connected with the second screw mandrel 25, and the power passes through the second electric motor 27, the second speed reducer 26, the second The screw rod 25, the second nut 24, and the second plunger 23 are transmitted, and finally converted into the output of the pressure liquid in the second plunger cylinder 22. By controlling the second motor 27, the pressure liquid in the second plunger cylinder 22 can be controlled. Flow direction, pressure, flow velocity, when the second motor 27 rotates forward, the second plunger 23 is pushed forward, forcing the liquid to flow out of the second plunger cylinder 22, forcing the pressure of the liquid to rise, and when the second motor 27 speeds up, the output liquid The flow rate also increases; when the second motor 27 reverses, the second plunger 23 is pulled back, forcing the liquid to flow into the second plunger cylinder 22; the signal output terminals of the second pressure sensor 21 and the second rotary encoder 28 are all connected to The controller 1 is connected, the second pressure sensor 21 detects the pressure of the output liquid of the second plunger cylinder 22, and transmits it to the controller 1, the second rotary encoder 28 is installed on the second motor 27, and the second motor 27 The rotation angle data is transmitted to the controller 1, which is converted into the rotational speed of the second motor 27 and the flow rate of the second plunger cylinder 22 output liquid by the controller 1;

The inlet of the first on-off valve 3 is connected to the plunger cylinder 12 liquid outlet of the first liquid output device 2, and the pipeline between the first on-off valve 3 inlet and the plunger cylinder 12 liquid outlet is provided with a bypass, and the second The on-off valve 4 is arranged on the bypass, the outlet of the second on-off valve 4 communicates with the liquid output port of the plunger cylinder 12, and the inlet of the second on-off valve 4 communicates with the liquid supply tank 6;

The inlet of the third on-off valve 7 is connected to the second plunger cylinder 22 liquid outlets, the pipeline between the third on-off valve 7 inlet and the second plunger cylinder 22 liquid outlets is provided with a bypass, and the fourth on-off valve 8 Set on the bypass, the outlet of the fourth on-off valve 8 communicates with the liquid output port of the second plunger cylinder 22, and the inlet of the fourth on-off valve 8 communicates with the liquid supply tank 6; the first on-off valve 3 and the third on-off valve 7 The outlet is connected and communicated with the pump liquid outlet 5; the signal output ends of the pressure sensor 11 and the rotary encoder 18 are all connected to the controller 1, the first on-off valve 3, the second on-off valve 4, the third on-off valve 7, and the fourth on-off valve 8 are all electronically controlled, the control terminals of the first on-off valve 3, the second on-off valve 4, the third on-off valve 7, and the fourth on-off valve 8 are all connected to the controller 1, and the controller 1 controls the first on-off valve 3, On-off of the second on-off valve 4, the third on-off valve 7, and the fourth on-off valve 8.

Its working state is the alternate cycle operation of the first and second liquid output devices. The state marked in Figure 1 is the state in which the first liquid output device 2 outputs pressure liquid, and the first liquid output device 2 absorbs liquid from the liquid supply tank. The two sets of liquid output devices operate alternately, which can realize the continuous output of pressure liquid; the specific working mode is the cyclic execution of the following steps (1), (2), (3), and (4).

(1) When the first liquid output device 2 outputs pressure liquid, the first switch valve 3 is opened, the second switch valve 4 is closed, the plunger 13 is pushed forward, and the pressure liquid is output through the pump liquid outlet 5; the pressure sensor 11 will The pressure value of the pressure liquid is transmitted to the controller 1, and the supporting rotary encoder 18 detects the rotation angle of the motor 17, and is transmitted to the controller 1, which is converted into the flow value of the pressure liquid by the controller 1, and the controller converts the pressure value, flow value Compared with the set value, the steering and rotational speed of the motor 17 are controlled through the comparison result, and then the pressure and flow rate of the pressure liquid are controlled.

(2) When the first liquid output device 2 outputs pressurized liquid, the second motor 27 of the second liquid output device 9 reverses to control the retraction of the second plunger 23, and the liquid is extracted from the liquid supply tank 3. The third on-off valve 7 is turned off, the fourth on-off valve 8 is opened, and the liquid in the liquid supply tank 3 enters the second plunger cylinder 22 through the fourth on-off valve 8; The device 1 controls the motor 27 to obtain the same pressure as the output liquid of the first liquid output device 1;

(3) When the plunger 13 of the first liquid output device 2 reaches the end of the stroke, the controller 1 will close the first switch valve 3, and the controller 1 will open the third switch valve 7, and the second liquid output The device 9 replaces the first liquid output device 2 to output pressure liquid;

(4) Afterwards, the second on-off valve 4 is opened, the plunger 13 of the first liquid output device 2 is retracted to absorb the liquid, and after the plunger cylinder 12 is filled, the second on-off valve 4 is turned off, and the controller 1 controls the motor 17 to keep the pressure. To be output; when the plunger 13 of the second liquid output device 9 reaches the end of the stroke, the controller 1 closes the third on-off valve 7, opens the first on-off valve 3, and continues to be output by the first liquid output device 2 pressure liquid.

Such reciprocating operation realizes uninterrupted output of pressure liquid. When one set of liquid output device is in operation, the pressure of the other set of liquid output device is controlled by the controller to keep equal to the pressure liquid. When the two sets of liquid output devices are switched, there is no pressure difference, thus ensuring the overall output pressure. smooth.

The types of the motor 17 and the second motor 18 are servo motors. Servo motor is used, which has high control precision and can better realize the adjustment of pressure and flow.

The type of controller 1 is PLC. In the field of automatic control, the control method of the motor has been mature, and there are many control methods to realize the control of the motor, such as PID control, etc., and the PLC control method is adopted, which is simple and easy.

The type of the screw rod 15 is a ball screw. The ball screw has small resistance, high motion precision and small transmission loss.

Embodiment 2

An embodiment of the first or second liquid output device of the present invention is illustrated in conjunction with accompanying drawing 2 .

In Fig. 2, the type of motor 37 is a servo motor, and rotary encoder 38 is installed on motor 37, and the output end of motor 37 is installed on the speed reducer 36, and the output section of speed reducer 36 is installed on the electric cylinder 39, and in electric cylinder 39 Lead screw, nut are provided, and plunger 13 is connected with the nut in electric cylinder 39, and the housing of electric cylinder 39 is equipped with transition support 40, and the plunger cylinder 32 that transition support 40 other ends is installed, and plunger 33 can be in plunger cylinder 32 Moving back and forth in the middle, the plunger cylinder 32 is provided with a liquid output port, and a pressure sensor 31 is installed at the liquid output port.

Claims (4)

1. A constant pressure and constant flow pump, comprising: a controller (1), a first liquid output device (2), a first switch valve (3), a second switch valve (4), a pump liquid outlet (5), Liquid supply tank (6), third switch valve (7), fourth switch valve (8), second liquid output device (9); first liquid output device (2) includes: pressure sensor (11), plunger Cylinder (12), plunger (13), nut (14), screw rod (15), reducer (16), motor (17), rotary encoder (18), plunger (13) installed in the plunger cylinder In (12), the plunger (13) is connected with the nut (14), and the nut (14) cooperates with the screw rod (15). The screw rod (15) and the nut (14) form a nut pair, and the screw rod (15) The rotation action is converted into the linear motion of the nut (14), and the plunger (13) is driven to move back and forth in the plunger cylinder (12) through the nut (14), and the power output end of the motor (17) and the power input end of the reducer (16) connection, the power output end of the reducer (16) is connected to the screw rod (15), and the power is transmitted through the motor (17), reducer (16), screw rod (15), nut (14), and plunger (13), Finally converted into the pressure liquid output in the plunger cylinder (12), the flow direction, pressure and flow velocity of the pressure liquid in the plunger cylinder (12) can be controlled by controlling the motor (17). When the motor (17) rotates forward, the plunger (13) is pushed forward to force the liquid to flow out of the plunger cylinder (12), forcing the pressure of the liquid to rise. When the motor (17) speeds up, the flow rate of the output liquid also increases; when the motor (17) reverses, the plunger (13) ) is pulled back to force the liquid to flow into the plunger cylinder (12); the signal output ends of the pressure sensor (11) and the rotary encoder (18) are connected to the controller (1), and the pressure sensor (11) detects the plunger cylinder (12) output the pressure of the liquid and transmit it to the controller (1); the rotary encoder (18) is installed on the motor (17), and transmits the rotation angle data of the motor (17) to the controller (1), Converted by the controller (1) to the rotational speed of the motor (17) and the flow rate of the liquid output by the plunger cylinder (12); The second liquid output device (9): the second pressure sensor (21), the second plunger cylinder (22), the second plunger (23), the second nut (24), the second screw rod (25), the second The second reducer (26), the second motor (27), the second rotary encoder (28), the second plunger (23) is installed in the second plunger cylinder (22), the second plunger (23) and The second nut (24) is connected, and the second nut (24) cooperates with the second screw mandrel (25), and the second screw mandrel (25) and the second nut (24) form a nut pair, and the second screw mandrel (25) The rotary motion of the second nut (24) is converted into the linear motion of the second nut (24), and the second plunger (23) is driven to reciprocate in the second plunger cylinder (22) by the second nut (24), and the power of the second motor (27) The output end is connected with the second speed reducer (26) power input end, and the power output end of the second speed reducer (26) is connected with the second screw mandrel (25), and power passes through the second electric motor (27), the second speed reducer ( 26), the second screw mandrel (25), the second nut (24), the second plunger (23) transmission, finally converted into the pressure liquid output in the second plunger cylinder (22), by controlling the second motor ( 27) The flow direction, pressure and flow rate of the pressure liquid in the second plunger cylinder (22) can be controlled. When the second motor (27) rotates forward, the second plunger (23) is pushed forward to force the liquid to flow out of the second column The plug cylinder (22) forces the pressure of the liquid to increase, and when the second motor (27) speeds up, the flow rate of the output liquid also increases; when the second motor (27) reverses, the second plunger (23) is pulled back , to force the liquid to flow into the second plunger cylinder (22); the signal output ends of the second pressure sensor (21) and the second rotary encoder (28) are connected to the controller (1), and the second pressure sensor (21) detects The second plunger cylinder (22) outputs the pressure of the liquid and transmits it to the controller (1); the second rotary encoder (28) is installed on the second motor (27), and the second motor (27) The rotation angle data is transmitted to the controller (1), and converted by the controller (1) into the rotation speed of the second motor (27) and the flow rate of the output liquid of the second plunger cylinder (22); The inlet of the first switch valve (3) is connected to the liquid output port of the plunger cylinder (12) of the first liquid output device (2), between the inlet of the first switch valve (3) and the liquid output port of the plunger cylinder (12) The pipeline is provided with a bypass, the second on-off valve (4) is set on the bypass, the outlet of the second on-off valve (4) communicates with the liquid output port of the plunger cylinder (12), and the inlet of the second on-off valve (4) Connected with the liquid supply tank (6); The inlet of the third on-off valve (7) is connected to the liquid outlet of the second plunger cylinder (22), and the pipeline between the inlet of the third on-off valve (7) and the liquid outlet of the second plunger cylinder (22) is provided with bypass The fourth on-off valve (8) is set on the bypass, the outlet of the fourth on-off valve (8) communicates with the liquid output port of the second plunger cylinder (22), and the inlet of the fourth on-off valve (8) communicates with the liquid supply tank (6) Communication; the outlets of the first on-off valve (3) and the third on-off valve (7) are connected and connected to the pump liquid outlet (5); the first on-off valve (3), the second on-off valve (4), the third on-off valve The on-off valve (7) and the fourth on-off valve (8) are all electronically controlled, and the first on-off valve (3), the second on-off valve (4), the third on-off valve (7), and the fourth on-off valve (8) The control terminals are all connected to the controller (1), and the controller (1) controls the first on-off valve (3), the second on-off valve (4), the third on-off valve (7), and the fourth on-off valve (8). on and off. 2. The constant pressure and constant flow pump according to claim 1, characterized in that, the electric motor (17) and the second electric motor (27) are servo motors. 3. The constant pressure and constant flow pump according to claim 1 or 2, characterized in that the type of the controller (1) is PLC. 4. The constant pressure and constant flow pump according to claim 1, characterized in that, the type of the screw (15) and the second screw (25) is a ball screw.