JP2000257800A - Liquid circulation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain temperature of a target apparatus constant by controlling liquid such as lubricating oil of a machine tool which is the target apparatus by a temperature regulation device of small capacity and a simple control system. SOLUTION: This device sends a flow rate changing command to a pump 10 of an inlet conduit 6 and a flow rate control valve 12 from an electronic control device 23 in accordance with at least either of outlet liquid temperature TO of a target apparatus 5, inlet liquid temperature TI and liquid tank liquid temperature TL, a driving changing command to a temperature adjustment device 13, controls a flow rate so as to make TO constant and controls temperature so as to make a temperature difference between TI and TO to be constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for circulating a liquid for cooling or heating so as to maintain the temperature of a specific portion or the whole thereof at a constant level by supplying the same to a machine tool, a synthetic resin molding machine, various kinds of test equipment, and the like. More particularly, the present invention relates to a liquid circulating apparatus suitable for a machine or a device having a thermal load fluctuation.

[0002]

2. Description of the Related Art For example, the lubricating oil of a spindle of a machine tool is cooled to prevent its own deterioration due to overheating and to prevent the spindle and bearings from being adversely affected by heat, or to prevent the rotation of the spindle at a low temperature from being lowered by heating. Things are widely done. It is also widely practiced to cool a mold in a molten state in a short time by cooling a mold of a synthetic resin injection molding machine.

[0003] Liquids such as oil and water, which are supplied to a target device such as a machine tool, a synthetic resin molding machine or various test devices to maintain a specific part or the whole thereof at a predetermined constant temperature, are transferred from the liquid tank to the target device. It circulates through the path of entering and then returning to the liquid tank, during which time it comes from one or both of cooling means and heating means composed of a refrigerator, a water-cooled or air-cooled cooler, an electric heater, etc. The liquid temperature is adjusted by a temperature adjusting device.

FIG. 2 is a diagram schematically showing an example of this, in which the liquid in a liquid tank 31 is supplied to an inlet line 33 provided with a pump 32.
To the target device 34, and then to the temperature controller 35
Is returned to the liquid tank 31 by the outlet pipe 36 provided with the circulating circuit. At the inlet and outlet of the target device 34, temperature sensors 37 and 38 for detecting the liquid temperature are provided, and based on the detected liquid temperature, an operation command is sent from the electronic control device 39 to the temperature adjusting device 35, and the outlet is output. The liquid is cooled or heated so that the liquid temperature becomes a predetermined temperature.

[0005]

SUMMARY OF THE INVENTION In a device for circulating a liquid while adjusting the temperature of a liquid so that the target equipment 34 is maintained at a predetermined constant temperature, when the heat load fluctuates in the target equipment 34, the fluctuation is caused. Is detected as a change in the outlet liquid temperature, and it is necessary to operate the temperature adjusting device 35 so that the temperature returns to a predetermined temperature set in advance.

[0006] For example, when the heat load increases, the inlet liquid temperature must be lower than before in order to quickly lower the outlet liquid temperature to a predetermined temperature, and the output of the temperature control device 35 must be increased. Must. Next, when the outlet liquid temperature drops to a predetermined temperature, the output of the temperature controller 35 is reduced or its operation is temporarily stopped to return the lowered inlet liquid temperature to an appropriate temperature, and thereafter, the heat load is reduced. The target device 34 is maintained at a predetermined constant temperature by taking the procedure of adjusting the inlet liquid temperature to a temperature at which the increase can be absorbed.

Accordingly, the inlet liquid temperature must be adjusted over a wide temperature range and in each case within a narrow temperature range with respect to various or large fluctuations of the heat load.
However, there is a problem that the system of No. 9 becomes extremely complicated and that a large-capacity temperature control device 35 must be used.

The present invention relates to a large-capacity temperature control device having a conventional liquid circulating device which circulates liquid to a target device having a heat load fluctuation and maintains the liquid at a predetermined constant temperature, a control system is extremely complicated, and a large-capacity temperature control device is provided. A liquid circulating device that is required to solve the above-mentioned problem that it is necessary to maintain a target device at a predetermined constant temperature with a simple control system without using a large-capacity temperature adjusting device. The purpose is to provide.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an inlet line having a pump for feeding liquid from a liquid tank to a target device and a method for returning liquid from the target device to the liquid tank. A circulation line comprising an outlet line, a temperature adjusting device provided separately from the circulation circuit to adjust the liquid in the liquid tank to a set temperature, a flow rate control means for the liquid to be fed into the target equipment, and an electronic type. A flow control command from the control device to the flow control means based on at least one of the outlet temperature, the inlet liquid temperature, and the liquid tank liquid temperature of the target device, and the operation change command to the temperature adjusting device. I sent it.

As described above, by using the means of controlling the flow rate of the liquid supplied to the target equipment in addition to controlling the temperature, the flow rate of the liquid is controlled in proportion to the change in the heat load, so that a small volume of liquid is controlled. The temperature difference between the inlet liquid temperature and the outlet liquid temperature can be kept constant by the temperature controller to absorb or compensate for the fluctuations in the heat load, which means that the flow rate can be adjusted so that the outlet liquid temperature reaches a predetermined temperature. This can be easily achieved by controlling the temperature of the liquid on the inlet side and the temperature of the liquid such that the temperature difference from the liquid temperature on the outlet side is constant.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. 1. A liquid tank 1 is divided into an inlet liquid tank 3 and an outlet liquid tank 4 by a partition plate 2. , The inlet line 6 from the liquid tank section 3 on the inlet side to the target device 5 and the target device 5
A circulation circuit 8 is formed by the outlet pipe line 7 extending from the outlet to the outlet-side liquid tank unit 4 and the internal liquid path of the liquid tank 1 and the target device 5.

The inlet line 6 has a pump 10 driven by a prime mover 9 and a flow control valve 12 operated by an actuator 11.

A temperature control device 13 is provided outside the liquid tank 1 separately from the circulation circuit 8, and an inlet conduit 14 extends from the outlet liquid tank unit 4 and an outlet conduit 15 is connected to the inlet liquid tank unit 3. Has reached. The inlet conduit 14 has a pump 17 driven by a motor 16.

Further, the temperature T _I , T _O , and T _L of the liquid at the respective locations of the inlet line 6 and the outlet line 7 near the target device 5 and the inlet side liquid tank 3 are detected. Temperature sensors 18, 19, 20 are provided. in addition,
In the illustrated embodiment, temperature sensors 21 and 22 for detecting the temperature T _M around the internal liquid path of the target device 5 and the temperature TA of the atmosphere around the target device 5 are provided.

On the other hand, an electronic control unit 23 is prepared, and the above-mentioned temperature sensors 18, 19, 20, 21, 21 are provided.
2 is input as an electric signal. The control device 23 sends a flow rate change command to the actuator 11 based on this signal and sends an operation change command to the temperature adjustment device 13.

The target device 5 is a machine tool, a synthetic resin injection molding machine, or a test device requiring a constant temperature. Further, the temperature adjusting device 13 includes one or both of a cooling unit such as a refrigerator, a water-cooled or air-cooled cooler, and a heating unit such as an electric heater. Further, the control device 23 is a microcomputer, and performs flow rate control and temperature control based on a control program selected from among fuzzy control, proportional control, and the like so as to be suitable for the specifications of the entire device.

In addition, a variable speed motor of, for example, an inverter control type may be used as the prime mover 9 for driving the pump 10 in the inlet line 6, and is driven by a flow control valve 12 and a variable speed motor operated by an actuator 11. The pump 10 constitutes the flow control means 24. The flow control means 24 may be constituted by one of the flow control valve 12 and the variable speed pump 10, but when both are constituted, each having a narrow duty range is used to achieve a large flow range. There is an advantage that appropriate flow control can be performed over the entire range.

In the liquid circulating apparatus having such a configuration, when the target device 5 is operated while circulating the liquid in the circulation circuit 8, the outlet liquid temperature T _O of the target device 5 is detected by the temperature sensor 19 and the control device is operated. 23. The outlet liquid temperature T _O is compared with a predetermined temperature set in advance. When the temperature is higher than this, the flow rate is increased so that cooling is promoted. The control device 23 outputs a signal of a flow rate change command to the flow rate control means 24 so as to measure the temperature rise to the temperature.

[0019] Here, the amount of heat Q of the liquid consumed for internal purposes device 5, the flow rate of liquid L, and the density [rho, the specific heat is c, inlet fluid temperature T _I or a bath liquid temperature T _L and an outlet Assuming that the temperature difference from the liquid temperature T _O is ΔT, it is expressed as follows: Q = L × ρ × c × ΔT

In the present invention, the variation of the heat quantity Q is mainly dealt with by changing the flow rate L, unlike the conventional one in which the variation of the heat quantity Q accompanying the variation of the heat load is dealt with by changing the above-mentioned ΔT. That is the biggest feature.

Therefore, the temperature T _I or T _L of the liquid sent from the inlet side liquid tank 3 to the target equipment 5 is measured by the temperature sensors 18 and 21.
Is input to the control device 23, and the operation change command is output to the temperature adjusting device 13 so that the inlet liquid temperature T _I or the liquid tank liquid temperature _TL that keeps ΔT constant. The required temperature difference ΔT can be provided only by adding a very simple and easy cooling or heating operation to the outlet liquid temperature T _O.

When the heat load of the target equipment 5 changes greatly, especially when the temperature rises significantly, in addition to increasing the flow rate Q, the operation of the temperature adjusting device 13 is raised to increase the inlet liquid temperature. By increasing the temperature difference ΔT by lowering T _I , it is possible to quickly absorb the increase in the thermal load. Conversely, it is when the temperature of the object device 5 is lowered in addition to reducing the flow rate Q, to reduce the temperature difference ΔT by raising the inlet liquid temperature T _I decrease or stop the operation of the temperature adjustment device 13 Thus, the decrease in the heat load can be promptly compensated. By these, the outlet liquid temperature T _O
After the temperature has recovered to the set temperature, the temperature controller 13 is operated so as to keep the temperature difference ΔT constant.

The flow rate control and the temperature control are performed at the inlet temperature T
It is performed by detecting any one of _I and the liquid tank temperature T _L. However, a temperature difference often occurs between T _I and T _L depending on the location and length of the inlet conduit 6. In such a case, by operating the temperature adjusting device 13 so that T _L is lower than T _I by the temperature difference, for example, T T
The temperature difference ΔT between _I and T _O can be a predetermined constant value, and using these temperature sensors 18 and 20 together is effective for achieving the object of the present invention.

Although the internal temperature T _M and the ambient temperature T _A of the target device 5 need not be detected, detecting either or both of them is performed by correcting the inlet liquid temperature T _I. This is advantageous when fuzzy control is performed by predicting the next temperature change. Further, the liquid tank 1 does not have to be divided into two sections, but the inlet-side liquid tank section 3 which receives the liquid whose temperature has been adjusted as shown in FIG.
When the liquid before the temperature adjustment sent from the target device 5 is divided into the outlet side liquid tank section 4 which receives the liquid before the temperature adjustment and sends the liquid to the temperature adjusting device 13, the temperature distribution of the liquid in the liquid tank is not uneven, and the liquid is stirred. And the temperature control becomes easy. The temperature adjusting device 13 may be installed inside the liquid tank 1 depending on its structure.

[0025]

As described above, according to the present invention, a small-capacity temperature control can be performed by a simple means of changing the flow rate of a cooling or heating liquid to be sent to a target device in accordance with a change in a heat load. The temperature of the target device can be kept constant by a simple control system using the device.

[Brief description of the drawings]

FIG. 1 is a layout diagram showing an embodiment of the present invention.

FIG. 2 is a layout diagram of a conventional example.

[Explanation of symbols]

1 liquid tank, 5 target equipment, 6 inlet line, 7 outlet line, 8 circulation circuit, 10 pump, 12 flow control valve, 1
3 temperature controller, 18, 19, 20 temperature sensor, 2
3 control device, 24 flow control means,

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G05D 7/06 G05D 7/06 Z 5H323 23/00 23/00 A F term (Reference) 3J071 AA12 AA13 BB02 BB14 CC07 DD26 EE01 EE02 EE18 EE27 FF16 3L044 AA01 BA06 CA12 DB01 DB02 FA02 GA02 HA03 JA01 KA05 4F202 AK13 AR06 AR14 CA30 CB01 CN01 CN05 CN13 CN22 4F203 AM25 AP05 AR06 AR14 AR20 DA12 DD01 DK07 DM10 5H307 DD08A05 BB05A03H04 BB11 CA08 CB23 CB33 CB35 DA04 DB13 DB15 EE01 EE11 EE13 EE17 FF04 FF10 HH02 KK05 MM06

Claims (6)

[Claims] 1. A circulation circuit comprising an inlet line having a pump for feeding liquid from a liquid tank to a target device and an outlet line for returning liquid from the target device to the liquid tank, and the circulation circuit. A temperature adjusting device that is provided separately from the liquid tank and adjusts the liquid in the liquid tank to a set temperature; a flow rate control unit for the liquid to be fed into the target device; and an electronic control device. The control device sends a flow rate change command to the flow rate control means based on at least one of the liquid temperature, the inlet liquid temperature, and the liquid tank liquid temperature, and sends an operation change command to the temperature adjusting device. Liquid circulation device. 2. The method according to claim 2, wherein the temperature is based on at least one of an outlet liquid temperature, an inlet liquid temperature, and a liquid tank liquid temperature of the target device. The liquid circulation device according to claim 1, wherein a command is sent from a control device to the flow rate control means and the temperature adjustment device. 3. An inlet-side liquid tank section in which the liquid tank receives the liquid whose temperature has been adjusted by the temperature adjustment device and sends the liquid to the target device, and receives the liquid sent from the target device and sends the liquid to the temperature adjustment device. The liquid circulation device according to claim 1, wherein the liquid circulation device is divided into two of an outlet-side liquid tank portion. 4. The liquid circulating apparatus according to claim 1, wherein said flow control means is a flow control valve provided in said inlet conduit. 5. The liquid circulation device according to claim 1, wherein said flow control means is said pump driven by a variable speed motor. 6. The liquid circulating apparatus according to claim 1, wherein said flow control means is a pump driven by a flow control valve provided in said inlet conduit and a variable speed motor.