JPH0517534Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention uses a water pump to send water in a water tank to objects to be cooled, such as laser processing machines and electrical discharge machines, and also uses water to cool objects to be cooled. This invention relates to a water cooling system that performs heat exchange between a cooling circuit that returns water to a water tank and a refrigerant circuit that includes a compressor, a condenser, and an evaporator via an evaporator.

[Prior Art] As a water cooling device that maintains the water temperature in the water tank at a preset target temperature by exchanging heat between the cooling circuit and the refrigerant circuit, the applicant of the present application has developed a water cooling system that uses water via the evaporator. A three-way electrically operated valve is interposed at the branching point between the water channel and the channel that does not pass through the evaporator, and the valve angle of the electrically operated valve is appropriately adjusted using proportional control based on the detection results of the temperature sensor in the water tank. We have already proposed something that performs control.

[Problems to be solved by the invention] Although electric valves are more suitable for controlling large flow rates than solenoid valves, they do not require frequent valve angle adjustment due to mechanical life and seal life problems caused by their mechanical configuration. is not suitable. However, in a system that proportionally controls the water temperature toward a single point, the target temperature Tr, of water in the water tank, frequent adjustments to the valve angle of the motorized valve are unavoidable, and frequent adjustments to the valve angle will reduce the mechanical lifespan. and seal life is shortened.

An object of the present invention is to provide a water cooling device that can control water temperature without frequently adjusting the valve angle of an electric valve.

[Means for Solving the Problems] To achieve this, in the present invention, a three-way valve type is installed at the branching part between the waterway passing through the evaporator and the waterway not passing through the evaporator. A temperature sensor is installed inside the water tank via an electric valve, and the temperature sensor is connected to a control device, and a control signal is output according to the water temperature detected by the temperature sensor outside the target temperature range of the water temperature in the water tank. A control device is connected to the electric valve, and control signal output from the control device to the electric valve is stopped in the target temperature range.

[Operation] When the detected water temperature exceeds the target temperature range, the control device issues a control signal to the motor-operated valve to lower the water temperature, and the proportion of return water from the heat load body passing through the evaporator increases. As a result, the amount of water flowing back into the tank via the evaporator increases, and the water temperature in the tank tends to decrease. Conversely, when the detected water temperature does not reach the target temperature range, the control device issues a control signal to the electric valve to increase the water temperature, and the proportion of return water from the heat load body passing through the evaporator is reduced. This increases the amount of water that flows back into the aquarium without going through evaporation, causing the water temperature in the aquarium to rise. When the detected water temperature falls within the target temperature range, the control device stops outputting the control signal to the motor-operated valve, and the motor-operated valve is stopped and maintained at the valve angle state immediately after the control signal output stops. Therefore, the operation of changing the valve angle of the motor-operated valve is significantly reduced, and the mechanical life and seal life of the motor-operated valve are improved.

[Example] Hereinafter, an example embodying the present invention will be described based on the drawings.

1 is a water tank, a water pump 3 is interposed on a supply pipe 2 connected to the water tank 1, and the supply pipe 2 is an introduction pipe 4 which becomes the waterway inlet of the heat load body 4
The reflux pipe 5, which is connected to the water tank 1 and the water tank 1, is connected to the discharge pipe 4b, which serves as a waterway outlet of the heat load body 4. One end of a cooling pipe 6 is branched and connected to the supply pipe 2 on the downstream side of the water pump 3, and the input port _P1 of a three-way valve type electric transmission valve 7 is connected to the other end of the cooling pipe 6. There is. One output port _P2 of the electric valve 7 is connected to the water tank 1 via a cooling pipe 8,
A discharge pipe 9 is connected to the other output port P ₃ of the electric valve 7 and its open end is placed above the water tank 1 .

The ball-shaped valve 7a of the electric valve 7 is connected to the motor part 7b.
is connected and fixed to the output shaft 7c of the ball-shaped valve 7a, and one opening of the passage 7d in the ball-shaped valve 7a is an input port.
It is always in communication with P ₁ , and the other opening can communicate with both output ports P ₂ and P ₃ . aisle 7d
is in communication with both output ports P ₂ and P ₃ within a certain range of rotation angle (i.e., valve angle) of the ball-shaped valve 7a, and outside this valve angle range, the passage 7d is connected to the output ports P ₂ and P ₃ It communicates with only one of them.
A reduction gear mechanism is incorporated in the motor section 7b, and this reduction gear mechanism causes the ball-shaped valve 7a to
can be stopped and held at any valve angle.

10 is a compressor, and a condenser 11 for liquefying refrigerant gas and a capillary tube 12 for restricting the flow rate of refrigerant liquid are connected in series to the discharge port side of the compressor, and a solenoid valve 13 for adjusting the flow rate is connected in series to the discharge port side of the compressor. The capillary tube 11 and the capillary tube 12 are connected in parallel. An evaporator 14 is connected to the suction port side of the compressor 10, and a capillary tube 12 and a flow rate adjustment solenoid valve 13 are connected to the evaporator 14 in parallel. Note that 15 is a fan.

The evaporator 14, which constitutes a refrigerant circuit together with the compressor 10, condenser 11, capillary tube 12, and flow rate adjustment solenoid valve 13, includes a water tank 1, a supply pipe 2, a water pump 3, a reflux pipe 5, a cooling pipe 8, and an electric motor. It is assembled into a cooling pipe 8 that constitutes a cooling circuit together with the valve 7 and the discharge pipe 9, and the cooling pipe 8 and the evaporator 14 constitute a cooler 16.

A temperature sensor 17 is installed in the water tank 1 to detect the temperature of the water, and a temperature detection signal from the temperature sensor 17 is input to a control computer C. The control computer C sends a control signal to the drive circuit 7e of the electric valve 7 based on the temperature detection signal from the temperature sensor 17. The control computer C has a target temperature range for the water temperature in the water tank 1.
T ₁ and T ₂ are input and set in advance, and the control computer C sets the water temperature Tx in the water tank 1 detected by the temperature sensor 17 to a preset target temperature range.
In cases other than T ₁ and T ₂ , valve opening control is performed on the motor-operated valve 7, and this valve opening control is performed by proportional control expressed by the following equation.

V(t) = Kp ΔT(t) = Kp ⋅ (tx(t) - Tr) where V(t) is the controlled variable expressed as the duty ratio, _Kp is the proportional element coefficient, and ΔT(t) is the target temperature.
This is the difference between Tr and the detected water temperature Tx.

When the detected water temperature Tx=Tx ₁ does not reach the target temperature range T ₁ , T ₂ , that is, when Tx ₁ < T ₁ , the control computer C sets the duty ratio V ₁ represented by the straight line L ₁ in FIG. Calculate (t)=Kp(Tx(t)−Tr),
A control signal for this duty ratio (curve D ₁ shown in FIG. 3a) is output to the drive circuit 7e. As a result, the ball-shaped valve 7a of the motor-operated valve 7 changes to the control signal curve.
Output port in angular unit Δθ according to the pulse width of D ₁
It rotates toward the _P3 side, and the amount of water returned from the discharge pipe 9 to the water tank 1 increases. Therefore, the water temperature in the water tank 1 increases, and the detected water temperature Tx moves toward the target temperature ranges T ₁ and T ₂ .

When the detected water temperature Tx=Tx ₂ exceeds the target temperature range T ₁ , T _{2 ,} that is, when Tx ₂ > T ₂ , the _{control computer C sets the duty ratio V 2 (} t)=Kp(Tx(t)-Tr), and calculate the control signal for this duty ratio (the curve shown in Figure 3b).
D ₂ ) is output to the drive circuit 7e. As a result, the ball-shaped valve 7a of the electric valve 7 follows the control signal curve D ₂
Output port P ₂ in angular units Δθ according to the pulse width of
The amount of water returned from the cooling pipe 8 to the water tank 1 increases. Therefore, the water temperature in the water tank 1 decreases, and the detected water temperature Tx moves toward the target temperature ranges T ₁ and T ₂ .

When the detected water temperature Tx reaches the target temperature ranges T ₁ and T ₂ , the control computer C stops outputting the control signal, and the valve angle of the electric valve 7 is maintained at the position immediately after the control signal stops. As a result, the electric valve 7 is not driven while the detected water temperature Tx is within the target temperature ranges T ₁ and T ₂ , and the number of operations in valve angle control is significantly reduced compared to a one-point target setting with no range. Decrease. Therefore, mechanical deterioration and reduction in sealing performance caused by frequent operations in valve angle control due to the mechanical configuration of the electric valve 7 are avoided;
The reliability of the electric valve 7 is greatly improved.

Furthermore, the configuration in which feedback control regarding the electric valve 7 is not performed leads to a simplified control system and is advantageous in terms of cost.

The present invention is, of course, not limited to the embodiments described above, and the valve angle of the electric valve 7 may be controlled in the same manner as in the embodiments described above using a control device having an electronic circuit configuration instead of, for example, computer control.

[Effects of the invention] As detailed above, the present invention has a three-way valve type that can separate the flow and can be stopped and held at any valve angle at the branching part between the waterway passing through the evaporator and the waterway not passing through the evaporator. When the valve angle of the motorized valve is controlled based on the water temperature information obtained from the temperature sensor in the water tank via the motorized valve, if the detected water temperature is outside the target temperature range, the motorized valve is operated using a control signal according to the water temperature detected by the temperature sensor. Since the valve is driven and the motorized valve is not driven when the detected water temperature is in the target temperature range, the number of changes in valve angle control in the motorized valve is reduced, thereby suppressing mechanical deterioration of the motorized valve and deterioration of seat performance. This has the excellent effect of significantly improving the reliability of the electric valve.

[Brief explanation of the drawing]

The drawings show an embodiment embodying the present invention, and FIG. 1 is a circuit diagram, and FIGS. 2 and 3 a and 3 are graphs. Water tank 1, water pump 3, electric valve 7, evaporator 14
A cooling pipe 8 as a waterway passing through the evaporator 14, a discharge pipe 9 as a waterway not passing through the evaporator 14, a temperature sensor 17, and a control computer C.

Claims (1)

[Scope of utility model registration request] The water in the water tank 1 is transferred to the heat load body 4 by the water pump 3.
At the same time, heat exchange is performed between a cooling circuit that circulates the water that has cooled the heat load body 4 into the water tank 1 and a refrigerant circuit that includes a compressor 10, a condenser 11, and an evaporator 14 via an evaporator 14. In the water cooling device, the water channel 8 passing through the evaporator 14 and the evaporator 1
A three-way electric valve 7 is interposed at the branching point with the water channel 9 that does not pass through the water tank 1, and a three-way electric valve 7 that can separate the flow and can be stopped and held at any valve angle is installed in the water tank 1. 17 is connected to the control device C, and a control device C is connected to the electric valve 7, and outputs a control signal according to the water temperature detected by the temperature sensor 17 outside the target temperature range of the water temperature in the water tank 1. A water cooling device configured to stop outputting a control signal from a control device C to an electric valve 7 in a temperature range.