FLOW RATE CONTROL DEVICE

Abstract

Provided is a flow rate control device capable of suppressing variation of supply pressure caused by variation of set flow rate and suppressing influence of pressure loss and cavitation on a secondary side. The flow rate control device (18) includes: a flow rate regulating valve (19) that regulates a flow rate of fluid flowing in a flow path; a flow meter (20) that measures the flow rate of the fluid flowing in the flow path; and a control portion (21) that controls an opening degree of the flow rate regulating valve (19) based on a measurement result of the flow meter (20), the flow rate regulating valve (19) is a three-way valve for dividing to regulate fluid flowing in from an inflow port (24) to a first outflow port (25) and a second outflow port (26), the flow meter (20) is connected to the second outflow port (26) side, and a multistage throttle orifice (22) for decompressing the pressure of the fluid in stages is provided on the first outflow port (25) side.

Claims

1. A flow rate control device for controlling a fluid flowing in a flow path that starts from an inflow port and is split to a first flow path leading to a first outflow port and a second flow path leading to a second outflow port, comprising: a flow rate regulating valve that instantaneously regulates a flow rate of the fluid flowing in the flow path; a flow meter that measures a flow rate in the second flow path to produce continuous measurement results of the flow rate; and a controller that receives the continuous measurement results of the flow rate, and instantaneously controls an opening degree of the flow rate regulating valve on each of the continuous measurement results of the flow rate produced by the flow meter, wherein the flow rate regulating valve is a three-way valve for dividing to regulate the fluid flowing to the first flow path leading to the first outflow port and the second flow path leading to the second outflow port, the flow meter is located in the second flow path and is connected to the second outflow port side, and a multistage throttle orifice is located in the first flow path and is provided on the first outflow port side, and wherein the multistage throttle orifice decompresses pressure of the fluid flowing out of the first outflow port in stages, thereby adjusting pressure balance and suppressing cavitation.

2. The flow rate control device according to claim 1, wherein the multistage throttle orifice is built in a valve adapter of the three-way valve.

3. The flow rate control device according to claim 1, wherein the multistage throttle orifice is arranged with a plurality of ring plates, and the plurality of ring plates have tapered throttle orifices whose apertures are narrowed from an inlet to an outlet.

4. The flow rate control device according to claim 2, wherein the multistage throttle orifice is arranged with a plurality of ring plates, and the plurality of ring plates have tapered throttle orifices whose apertures are narrowed from an inlet to an outlet.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0020] FIG. 1 is an overall diagram showing an example in which a flow rate control device of the present invention is applied to a mold temperature control system.

[0021] FIG. 2 is a partial cross sectional view showing the configuration of the flow rate control device of the present invention.

[0022] FIG. 3 is a schematic view showing a switching mode of a flow rate control valve in the flow rate control device of the present invention.

[0023] FIG. 4 is an enlarged exploded view showing the configuration of a multistage throttle orifice in the flow rate control device of the present invention.

[0024] FIG. 5 is a partial cross sectional view showing a variation example of the flow rate control device of the present invention.

[0025] FIG. 6 is a partial cross sectional view showing a variation example of the flow rate control device of the present invention.

[0026] FIG. 7 is an explanatory view showing a general flow rate characteristic of a two-way valve.

[0027] FIG. 8 is an explanatory view showing a general flow rate characteristic of a three-way valve.

[0028] FIG. 9 is an explanatory view showing flow rate characteristics in the case that there is pressure loss on the B port side of the three-way valve.

[0029] FIG. 10 is an explanatory view showing flow rate characteristics when a throttle orifice is provided on the A port side of a three-way valve.

[0030] FIG. 11 is an explanatory view showing a configuration in which a multistage throttle orifice is provided on the A port side of a three-way valve.

[0031] FIG. 12 is an explanatory view showing a configuration in which a multistage throttle orifice is provided by arranging ring plates on the A port side of a three-way valve.

[0032] FIG. 13 is an explanatory view showing a configuration in which a valve adapter on the A port side of a three-way valve has built-in a multistage throttle orifice.

[0033] FIG. 14 is an explanatory view showing a flow rate control device including a flow rate regulating valve including a three-way valve containing a multistage throttle orifice, a flow meter, and a controller (control portion).

A LIST OF REFERENCE NUMBERS

[0034] 1: mold temperature control system [0035] 2: die casting machine [0036] 3: mold [0037] 4: fixed mold [0038] 5: movable mold [0039] 6: temperature sensor [0040] 7: control device [0041] 8: cooling water circulating device [0042] 9: cooling tower [0043] 10: heat exchanger [0044] 11: tank [0045] 12: pump [0046] 13: water supply pipe [0047] 14: mold pipe [0048] 15: backflow pipe [0049] 16: flow rate control unit [0050] 17: manifold [0051] 18: flow rate controller [0052] 19: flow rate regulating valve [0053] 20: flow meter [0054] 21: controller [0055] 22: multistage throttle orifice [0056] 23: adapter [0057] 24: inflow port [0058] 25: first outflow port [0059] 26: second outflow port [0060] 27: valve body [0061] 28: valve core [0062] 29: actuator [0063] 30: stepping motor [0064] 31: motor bracket [0065] 32: valve shaft [0066] 33: valve [0067] 34: sliding O-ring [0068] 35: shaft packing [0069] 36: retainer lock [0070] 37: screw [0071] 38: magnet [0072] 39: magnetic sensor [0073] 40: Hall IC [0074] 41: rectifying plate [0075] 42: wave washer [0076] 43: valve adapter [0077] 44: ring plate [0078] 45: tapered throttle orifice [0079] 46: L-shaped elbow

DETAILED DESCRIPTION

[0080] In the following, reference to the drawings will be made to explain the way of implementing the present invention.

[0081] FIG. 1 shows an embodiment of constructing a mold temperature control system using the flow rate control device of the present invention. The mold temperature control system 1 of the present embodiment is a system for controlling the temperature of the mold 3 by changing the flow rate of cooling water controlled at a constant flow rate during production in a die casting machine 2 for producing (casting) an aluminum die casting product. The mold 3 forms a part of the die casting machine 2 and consists of a fixed mold 4 provided in an injection device and a movable mold 5 provided in a mold clamping device.

[0082] A temperature sensor 6 ( . . . 6n) composed of a thermocouple or a temperature measuring resistor is mounted at respective parts of the mold 3 (the fixed mold 4 and the movable mold 5). The temperature sensor 6 detects the highest temperature, the lowest temperature, the average temperature, and the current temperature of the mold 3 during the production cycle in real time. The detected temperature information of the mold 3 is converted into an electrical signal and output to a control device 7 that performs an arithmetic process described later.

[0083] As a mechanism for adjusting the temperature of the mold 3, a cooling water circulating device 8 for circulating cooling water is provided outside the die casting machine 2. The cooling water circulating device 8 is configured to include a cooling tower 9, a heat exchanger 10, a tank 11, and a pump 12. The water in the tank 11 is cooled by the cooling tower 9 via the heat exchanger 10. The cooling water is supplied by the pump 12 through a water supply pipe 13 and a mold pipe 14 to cooling water holes provided in the respective parts of the mold 3, and circulates to the tank 11 through a backflow pipe 15.

[0084] A flow rate control unit 16 is mounted on the mold 3 (the fixed mold 4 and the movable mold 5), respectively. The flow rate control unit 16 includes a manifold 17 connected to the water supply pipe 13 and an aggregate of a plurality of flow rate controllers 18 ( . . . 18n) coupled to the manifold 17. In the manifold 17, cooling water from the water supply pipe 13 is introduced into a cavity via a strainer (not shown), and is branched at a plurality of ports to be supplied to the respective flow rate controllers 18 ( . . . 18n).

[0085] The flow rate controller 18 is a flow rate control device for controlling the instantaneous flow rate of cooling water which cools the respective parts of the mold 3 (the fixed mold 4 and the movable mold 5). As shown in FIG. 2, the flow rate controller 18 includes a flow rate regulating valve 19, a flow meter 20, a controller (control portion) 21, and a multistage throttle orifice 22, and is connected to a port of the manifold 17 via an adapter 23.

[0086] The flow rate regulating valve 19 is a three-way valve of a dividing type which divides fluid flowing in from an inflow port 24 to a first outflow port 25 and a second outflow port 26 and adjusts the flow rate ratio flowing out of the two outflow ports. The inflow port 24 is connected to the water supply pipe 13 for supplying cooling water from the pump 12, and the first outflow port 25 is connected to the backflow pipe 15 for returning the cooling water to the tank 11. In addition, the second outflow port 26 is connected to the mold pipe 14 for supplying cooling water to the cooling water hole of the mold 3, and a pipe system on the side (one side) of the second outflow port 26 is as a flow rate control object.

[0087] The flow rate regulating valve 19 of the present embodiment adopts an electric rotary valve mechanism, and drives a valve core 28 built in a valve body 27 by electric force of an actuator 29, and adjusts valve opening degree by the electric force. The actuator 29 has a built-in stepping motor 30 and is mounted to a valve body 27 via a motor bracket 31. The valve core 28 includes a valve shaft 32 and a valve 33 provided at the front end thereof and is coupled to a rotating shaft of the stepping motor 30. It should be noted that 34 denotes a sliding O-ring, 35 denotes a shaft packing for pressing the valve shaft 32 to act as a throttle orifice, and 36 denotes a retainer lock for pressing the shaft packing 35 to fix it.

[0088] As shown in FIG. 3, the flow rate regulating valve 19 constituted by a three-way valve is configured that, when an opening portion of the second outflow port (B port) 26 is switched from a fully closed state (opening degree 0%) to a fully open state (opening degree 100%), then along with this, the opening portion of the first outflow port (A port) 25 is switched from the fully open state to the fully closed state, and the flow rate ratio of cooling water flowing out of the two outflow ports (A and B ports) can be adjusted. It should be noted that even if the valve 33 of the valve core 28 rotates so that the flow rate ratio of the cooling water flowing out from the first outflow port (A port) 25 and the second outflow port (B port) 26 vary, the flow rate (total flow rate) of the cooling water flowing in from the inflow port (C port) 24 is substantially constant.

[0089] The flow meter 20 measures the flow rate of the fluid flowing out of the second outflow port 26 and an impeller type flow meter is used in the present embodiment. The impeller type flow meter is configured to include a screw 37 supported in a flow path so as to be rotatable, and a magnetic sensor 39 for detecting a magnet 38 sealed by a blade portion of the screw 37. The magnetic sensor 39 is a non-contact sensor having a Hall IC 40 comprising of a Hall element, a power supply circuit, an amplifier, and the like built in, the Hall IC 40 detects a magnetic field of the magnet 38 and outputs an electrical signal to the controller 21. It should be noted that 41 denotes a rectifying plate for rectifying so as to prevent turbulence of the fluid flowing into the flow path after flow dividing, and the rectifying plate 41 also serves as a bearing for the screw 37. In addition, 42 denotes a wave washer for pressing the rectifying plate 41 to prevent loosening.

[0090] The controller (control portion) 21 is a microcomputer having functions of flow measurement, motor control, PID flow control and the like. The controller 21 measures a flow rate value calculated based on the rotational speed of the screw 37 according to the electrical signal output from the magnetic sensor 39. The controller 21 controls the stepping motor 30 of the actuator 29 based on the measured flow rate value and a set flow rate value input from the control device 7, and performs feedback control (PID control) on the opening degree of the flow rate regulating valve 19.

[0091] The multistage throttle orifice 22 decompresses the pressure of the fluid flowing out of the first outflow port 25 in stages, and the multistage throttle orifice 22 has a function of adjusting a pressure balance and a function of suppressing cavitation. The multistage throttle orifice 22 of the present embodiment is built in a valve adapter 43 connected to the valve body 27 so that compactness and reduction of the sealing position are achieved. In addition, As shown in an enlarged view in FIG. 4, the multistage throttle orifice 22 is arranged in a thickness direction by a plurality of ring plates 44 (five in the present embodiment), so that the multistage throttle orifice 22 is compact and not easily clogged with dirt. On one side (inlet side) of each ring plate 44, a tapered throttle orifice 45 whose aperture gradually narrows from an inlet to an outlet is provided.

[0092] As described above, according to the flow rate controller 18 of the present embodiment, by controlling the distribution amounts of the first outflow port 25 and the second outflow port 26 using a three-way valve in the flow rate control valve 19, it is possible to suppress a variation of a supply pressure of the pump 12 according to the flow rate of the flowing cooling water, and to suppress mutual interference among respective piping systems. In addition, a tapered throttle orifice 45 is provided within the valve adapter 43 so as to prevent deterioration in a balance of flow rate characteristics due to a difference in a back pressure between the first outflow port 25 side and the second outflow port 26 side, thereby enabling precise flow rate control. In addition, by adopting the multistage throttle orifice 22 in which a plurality of ring plates 44 having the tapered throttle orifice 45 are arranged, the pressure of the fluid flowing out of the first outflow port 25 can be decompressed in stages, and cavitation caused by lower back pressure can be suppressed.

[0093] It should be noted that, although a T-shaped three-way valve is used as the flow rate regulating valve 19 constituting the flow rate controller 18 in the above-described embodiment, variation examples such as those shown in FIGS. 5 and 6 may be used. Since the valve throttle of the flow regulating valve 19 is provided at the inlet of the flow meter 20, it can be considered that there are adverse effects on the flow characteristics due to turbulence from the valve. Therefore, for the purpose of preventing such adverse effects, the flow rate controller 18A shown in FIG. 5 connects the flow meter 20 to the valve body 27 via a L-shaped elbow 46, and the flow rate controller 18B shown in FIG. 6 further connects the multistage throttle orifice 22 to the valve body 27 via the L-shaped elbow 46. In this way, by making piping zigzag by using the L-shaped elbow 46, the fluid flowing in the flow path collides with an inner wall, thus extreme turbulence can be suppressed in a short distance. Moreover, in the case of the impeller type flow meter according to the present embodiment, a sliding resistance of a shaft of the screw 37 is reduced by making a mounting position of the flow meter 20 vertical, thus the low flow rate characteristic is improved and the flow rate measurement can be performed in a wide range.

[0094] In the above described embodiment, the mold temperature control system of the die casting machine is constructed using the flow rate control device of the present invention, but an application example of the present invention is not limited thereto. For example, in a piping system provided with a plurality of injection molding machines using cooling water and/or a machine tool using cutting oil and so on, the present invention can be applied to a purpose of changing a supply amount of fluid such as cooling water, a refrigerant liquid, a cutting oil, etc. according to a variation in the number of operating tables of the machine. It should be stated that in the mold temperature control system described above, the instantaneous flow rate of the cooling water is controlled by the flow rate controller, but an accumulated flow rate may be controlled by controlling the instantaneous flow rate and counting an accumulated value.