JPH0571880B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to controlling the rotational speed of a load device with large inertia, such as a blower fan, in order to automatically control the temperature of a control medium such as cooling water in a cooling tower. The present invention relates to a temperature control device that can change the temperature proportionally or continuously.

[Prior art]

Conventionally, as a schematic structure of this type of temperature control method for a control medium, a method using a stepless reducer as shown in FIGS. 1A and 1B has been considered. However, both the power transmission method and the more specific speed change control method remained beyond mere ideas and were not put into practical use.

FIG. 1A shows its configuration diagram. In the figure, 1 is a cooling tower, 2 is a water sprinkler, 3 is a filler, 4 is a water tank, 5 is a cooling water inlet pipe, 6 is an outlet pipe, and 7 is an air flow. The principle is that heated cooling water is sprayed by a sprinkler 2, cooled by an air flow 7 from below, and then returned to an outlet 6. This is intended to control the speed of the blower in order to continuously change the amount of airflow 7.

10 is a stepless reducer, 11 is a blower motor, 12 is a gear reducer, 13 is a blower fan, 14 is a power source, 1
5 is a computer, and 16 is a sensor.

Here, the processing is performed by the computer 15 and a speed change signal is given to the stepless reducer 10 to control the rotational speed of the blower fan 13.

〔problem〕

Although those skilled in the art have come up with this type of idea many times in the past, all of them have remained beyond ideas, failed to put them into practical use, and have not been commercialized.
The reason for this was mainly due to the following two points.

The first reason is that the transmission part will be damaged in a short period of time because the continuously variable reducer 10 cannot withstand a large inertial load such as a blower fan, and the second reason is that the transmission part will be damaged in a short period of time. The problem was that no solution could be found as to whether the configuration should be automatically controlled.

For example, the description will be made using a conventionally well-known stepless reduction gear 10. FIG. 1B is a sectional view of a metal friction type transmission, which is an example of a static friction drive system. In this figure, only a cross-sectional view of the half side from the axis center is drawn. In the figure, A is the input shaft, B is the output shaft, C is the sun wheel, and the fixed side car C ₁ and the moving side car C ₂ constantly hold the planet wheel E with the spring D, while the planet wheel E and the carrier F are linked. G is a gear ratio control unit, which allows the planetary wheels E to be moved in the radial direction using a fixed ring _G2 and a moving cam _G1 . In this structure, the planet wheel E plays the role of a variable planet, and the gear ratio is controlled by the interval between the cracks by operating the moving cam _G1 .

However, when this type of friction transmission method between metal wheels C and E is applied to a large inertial load such as a blower,
The following phenomenon occurs.

In a blower, when transmitting power from input shaft A to output shaft B, in a planetary wheel, point Z is the fulcrum and contact point X
is rotated in the tangential direction, thereby extracting the output from the Y point, so torque is transmitted smoothly by the viscous drag in the lubricating oil. However, on the other hand, with a large inertia load, when the main motor 11 is stopped, or even when the main motor 11 is not stopped but the moving cam _G1 is operated to the deceleration side, inertia remains on the load side, so power transmission is not normally performed. Power is transmitted from the output shaft B side to the input shaft A side. During this reverse transmission, the planetary wheel E has its fulcrum as the Z point and the Y point as the point of action, so the original transmission point, the X point, receives an irregular external force, and as a result, the viscous transmission by the lubricating oil is not properly carried out. This did not work, and the metal contact surfaces of the planet wheel E and the sun wheel C were damaged instantaneously, and if this was repeated, the metal contact surfaces of the planet wheel E and the sun wheel C would become scraped in a short period of time.

Furthermore, in addition to the inherent drawbacks of the continuously variable reducer 10, the second reason is that the technology for controlling the gear ratio of the continuously variable reducer 10 has not been established. Because of this, mechanical speed control of the blower was not implemented.

〔the purpose〕

When driving a load device that changes the temperature of a control medium, this invention provides an acceleration/deceleration type power transmission method using line or surface contact using a belt, instead of transmitting power through point contact between metals as described above. The purpose of the present invention is to provide a temperature control device that uses a belt transmission to achieve stable transmission, and that includes a control medium to form a feedback closed loop to precisely adjust the temperature of the control medium. There is.

[Technical means to solve problems]

The temperature control device of the present invention includes a temperature detector for a control medium regulated by a load device, and an automatic control regulator that supplies a proportional output signal of a predetermined gear ratio to a pilot electric controller in accordance with the temperature signal of this detector. , a pulley device in which a speed change belt is held between a fixed pulley and a sliding pulley is provided at the input and intermediate shafts, and is directly connected to one of the sliding pulleys of the pulley device so that the sliding pulley is connected to the fixed pulley. a speed increasing/decelerating type belt transmission having the above-mentioned pilot electric controller for controlling the speed change by moving up and down, a speed reducer for transmitting the rotational power of the intermediate shaft to the above-mentioned load device, and further the above-mentioned load device. A feedback closed loop is formed.

[Effect]

When operating such an automatic control loop,
This is determined by the reliability of the blower electric transmission itself, which corresponds to the operating end of the control system, and the quality of control followability, and whether or not a high-precision system exists. The mechanical belt transmission is highly durable against loads, and the gear ratio is controlled by a pure electric servo adjuster.
Since the advantages or effects of both are directly exhibited during temperature control, as a result, highly durable continuous stable operation and highly accurate temperature control are simultaneously realized.

〔Example〕

In FIG. 2, a partial cross-sectional view of the double suction type cross-flow cooling tower 10 is shown as an embodiment. In the figure, 11 is a water tank, 12 is an air inlet louver, 1
Reference numeral 3 indicates a filler, 14 an eliminator, and 15 a partition wall. Cooling water is supplied from an inlet pipe 17 to a water sprinkling tank 16 above these. Further, a cylindrical fan stack 24 is assembled in the center, and an air outlet 20 is provided at the top of the fan stack 24, between which a blower fan 21 and a gear reducer 22 are installed in the center of a pipe stay 23 that is radially incorporated. Ru.

Furthermore, the top plate 2 adjacent to the fan stack 24
5 includes an induction motor 27, a pilot electric controller 29, and these electric motors 27 and controllers 29.
A variable power mechanism 26 is installed, which is comprised of an increase/decrease type belt transmission 28 which is integrally assembled with a variable power mechanism 26.
Further, the rotational output of the transmission 28 is coupled to the gear reducer 22 by a coupling 30 and a transmission body 31. In addition, the transmission 28 has a mechanism in which the cooling air is circulated through the closed chamber of the transmission 28 via the piping 36 from the cooling air inlet 35 and then released from the exhaust port 37 in order to insulate the frictional heat between the belt and the pulley. This is aimed at improving the belt life rate. 40 and 41 are wiring for power supply and control signals.

FIG. 3 is a configuration diagram of the speed-up/down type belt transmission 28. As shown in FIG. This transmission 28 includes a frame body 45 and a lid body 46.
A sealed chamber is formed to prevent moist air from entering, and the motor rotation shaft, that is, the input shaft 51 is located inside.
Fixed pulleys 54a and 55a for clamping the speed change belt 53 are provided on the intermediate rotating shaft 52 and the intermediate rotating shaft 52, respectively.
A pair of pulley devices 54 and 55 consisting of sliding pulleys 54b and 55b are attached. The drive-side pulley device 54 includes an impeller 56b attached to a sliding pulley 54b, and a spiral casing 56a.
A vortex centrifugal blower device 56 consisting of the following is attached, and a portion of the casing 56a communicates with the pipe 36', which in turn communicates with the introduction pipe 36 shown in FIG.
This introduces heat-insulated air into the room, and
It is discharged from 7. Pilot electric controller 2
9 is connected to an adjusting hoisting screw 57, and as the adjusting hoisting screw 57 rotates in the forward or reverse direction, the guide ring 58 moves up and down, thereby causing the fixed pulley 54a to move up and down.
The gear ratio is controlled by adjusting the distance between the sliding pulley 54a and the sliding pulley 54a.

This pilot electric controller 29 and pulley device 5
A reversible electric motor 79, an adjustment hoisting screw 57, and a guide ring 58, which are interposed between the servo adjustment system and the servo adjustment system, function to convert electrical and mechanical signals.

That is, when the contact radius between the pulley device 54 and the variable belt 53 changes, the contact radius also changes on the driven side, which is simply held by the spring force, and this cooperative operation controls the gear ratio. be done.
For belt conversion and maintenance, the intermediate shaft 52 is cantilever-supported by two bearings 59a and 59b, with one end being a free end, and the lid 46 is separable from the frame 45. The shaft support 60 has an adjustment mechanism using a bolt 62 and an elongated hole 6 so that it can be slid with respect to the frame 45.
1.

In the present invention, as described above, the first stage transmission is combined with an increasing/decelerating type belt transmission, and the second stage is combined with a constant reduction ratio speed reducer. Here, the increasing/decelerating type belt transmission is one that can change the speed of the intermediate shaft 52 both in the direction of speeding up and in the direction of decelerating the input rotational speed of the electric motor. Therefore, it is different from a continuously variable reducer that can only change speed in the deceleration direction in response to an input.

It has been found that such a combination of an increase/decrease type belt transmission and a speed reducer has the following synergistic effect, and works as a sufficiently stable and advantageous transmission even with a load of large inertia.

First, with a large inertial load, even if the large inertial power of the load is reversely transmitted when a deceleration command is issued from the pilot electric controller during operation, the elastic force of the belt itself and the spring of the driven pulley device It has the advantage of being able to relieve the stress through three actions: recovery and slippage between the belt and pulley, and this guarantees durability when continuously operating a large inertial load.

Second, in the combination of an increasing/decelerating type transmission and a reducer,
Particularly in the increase/decrease range, the pulley devices 54 and 55 increase the input rotation speed, and then the reducer 2
Although it may seem like a waste of time to decelerate the speed in step 2, this has an advantageous effect on making the equipment smaller, more economical, and easier to maintain.

From the first point, when the electric motor 27 is stopped, the contactor 4R is stopped, as is clear from FIG. 4, so the pilot electric controller 29 is also stopped (described later). Therefore, the rotating force in the opposite direction applied from the blower fan 21 via the reducer 22 is simply the belt 5
However, when deceleration is commanded during operation, the fan still maintains the high-speed inertia before the command, and on the other hand, the pilot electric controller 29 forcibly rotates the rotor of the electric motor 27. The electric motor 29 also applies a large rotational force to the input pulley 54 while acting on the input pulley 53 together with the spring 55c. Therefore, the stress of the speed between the high-speed inertial force of the load before the command and the rotational force of the electric motor is necessarily applied directly to the line or surface contact portion of the belt and pulley even in this case. In this case, in belt transmission, the elastic force mainly made of synthetic rubber such as neoprene absorbs this stress, and if this stress cannot be absorbed, a slip occurs between the belt and the pulley due to the escape of the pulley spring 55c, and the belt material Even if it wears out, it has the effect of absorbing this speed stress. This is fundamentally different in principle from the metal friction reducer mentioned earlier, and the situation where the metal transmission wheel itself is damaged is not part of the present invention, and the belt becomes a consumable item. The guarantee function works by actively utilizing this fact.

Furthermore, as a second advantageous condition, miniaturization and economy can be achieved. In other words, as a characteristic of the blower fan itself, its shaft horsepower W is proportional to the cube of the rotation speed N, and maximum power is required at maximum speed increase.
At this time, the capacities of the belt transmission and reducer may be selected based on the transmitted horsepower. In other words, in a normal belt transmission body, if the transmitted horsepower W ₀ is constant, the horsepower is proportional to the product (N T) of the rotation speed N and belt tension T, so if a transmission that works as a speed increaser is used, Since the number of rotations N is high, the tension T applied to the belt can be reduced accordingly. This means that the first stage transmission can use extremely small and inexpensive belts and pulleys. This has a great economic effect because it is placed on the top of the tower, which simplifies the structure of the tower itself and facilitates maintenance.

FIG. 4 is a block circuit connection diagram of the automatic cooling water temperature control and adjustment device. A temperature detector 67 is provided at a cooling water outlet 65 of the cooling tower 10 and connected to a servo regulator 70 . The servo controller 70 includes a bridge input circuit 71, an operational amplifier 72, and a filter 7.
3. Operational amplifier 74, positive feedback circuit 75, dead band circuit 76, speed increase and deceleration side output switch circuit 77
and 78. Further, the output switch circuits 77 and 78 have their contacts 77a
and the pilot electric controller 29 via 78a.
It is connected to the. On the other hand, the pilot electric controller 29 is connected to an input shaft side pulley device 54 in the speed-up/down type belt transmission 28. The cooling water temperature detector 67, the servo regulator 70, the pilot electric controller 29, the belt transmission 28, the speed reducer 22 and the blower fan form a first feedback circuit. Power supplies 8' and T' to the pilot electric controller 29 having the reversible motor 79 are supplied from the S and T terminals of the three-phase power supply line 83 to the blower motor 27. On the other hand, this power line 8
3 includes a start/stop control circuit 80 and a low temperature section control circuit 8.
1 is connected.

The operation of this servo adjuster 70 is as follows. When the start switch SW is pressed, normally closed contact 2R
The relay 3R operates via the contact 3R1, and the power to the servo regulator 70 (not shown) is turned on. It doesn't work because it's open. Next, while the temperature of the cooling water is maintained within the proportional operation region of the servo controller 70, the contact of the mechanical temperature detector 68 for low temperature region control is closed, so the low temperature region control is controlled. The circuit 81 is activated when the contact 3R1 is closed, and at this time, the contact 3R2 is closed and the relay 4R is energized. Therefore, the blower motor 27 operates via the three contacts 4R1. At the same time, interlock contact 4R
2 closes, the pilot electric controller 29 operates and performs normal proportional control operation. As is clear from FIGS. 3 and 4, the pilot electric controller 29 has a built-in reversible electric motor 79 and a gear reducer.
A part of the shift pulley 5 rotates the adjusting hoisting screw 57 in the forward or reverse direction according to the signal from the servo adjuster 70.
It is used to control the speed change by moving the No. 4 sliding pulley 54b against the spring 55c. Further, this electric motor 79 also has a power transmission body, that is, a gear reduction gear, connected to a bridge circuit 71, in which the state of the gear ratio is detected by a variable resistor, and a second feedback circuit of the servo adjustment system is activated. configured,
Arbitrarily variable speed control of fan rotation speed.

Although an example is shown in which the adjusting hoisting screw 57 is installed on the pulley device 54, other types may be used, and the adjusting hoisting screw 57 may be integrated with the reversible motor 79.

At this time, if the outside air wet bulb temperature is constant, the rotation speed of the blower fan will increase as the cooling water temperature rises, but even if the high limit switch HL of the pilot electric controller 29 closes, the blower fan will increase to the maximum speed. Continuous operation in this condition. Furthermore, when the cooling water temperature drops, even if low limit switch LL closes and relay 1R closes, relay 3R is still energized by contact 2R2, so blower motor 27 continues to rotate. The blower fan 21 rotates at the lowest speed.

At this time, when the cooling water temperature drops further as in winter, the liquid-filled inlet water or outlet water temperature detector 68 is activated, the relay 4R is deenergized, and the main motor 27 can be stopped. ing. That is, when the cooling water temperature is within the proportional band range of the servo controller 70, the fan rotation speed is proportionally controlled according to the temperature, and when the temperature falls below the proportional band range, automatic start/stop control of the main motor 27 is performed. It is configured so that it can be switched.

Next, to completely stop this device, press the stop switch SW, energize relay 2R, and contact 2R.
1 and 2R2 are inverted, and at the same time, the contacts of the bridge input circuit 71 of the servo regulator 70 (not shown)
, and sends out a signal that causes only the deceleration output switch circuit 78 to operate. Then, the pilot electric controller 29 receives this deceleration command and eventually lowers the speed.
Limit switch LL is closed, relay 1R is deenergized, contact 1R1 is opened, relay 3R is deenergized, regulator 70 stops operating, and relay 4R is stopped via contact 3R2. That is,
The start/stop control circuit 80 performs slow start control in this way, and when stopped, the belt 53 is stopped at its maximum deceleration, achieving ease of maintenance, and at the same time, the blower fan is always turned on at the next restart. lowest speed,
That is, the engine is started from the lightest load state based on the principle of the power cube reduction law mentioned above. For this reason,
Particularly during startup, there is an advantage that auxiliary equipment such as a reactor starter is not required. Note that the slow start control performed in the start/stop control circuit 80 and the blower device 56 described above are both mere belt protection measures; the former is for relieving the belt impact at the time of start, and the latter is for preventing friction. This is a measure to prevent the belt material from being cut due to softening due to heat, and is merely an auxiliary measure to improve durability toward full automation, which is the gist of the present invention, and is not directly related to the gist of the invention.

[Other Examples]

FIG. 5 is a partial configuration diagram of a cooling tower blower system according to another embodiment of the present invention, in which a belt reducer 85 is added to the reducer 22 shown in FIG. are using. As mentioned earlier, this system has the property that the belt 31' of the reducer 29 also actively absorbs the stress caused by the difference between the rotational force returned from the large inertia load side and the rotational force from the electric motor when a deceleration command is issued. Therefore, it has a better effect against this stress, and has the advantage of reducing wear on the belt of the belt speed change on the acceleration/deceleration side.

[Effects of the present invention]

Conventionally, a large horsepower, high inertia blower fan has been used to cool the control medium, but since it was difficult to control the rotational speed of the blower fan, bypass flow control using a three-way valve, etc. As a result, most of the methods involved controlling the temperature of the control medium. As a result, temperature fluctuations were large and it was impossible to expect highly accurate adjustment. However, according to the present invention, the main power is transmitted by an increase/decrease type belt transmission that has extremely stable durability against large inertial loads, while the gear ratio is controlled by a pure electric servo regulator. As a result, a highly reliable and highly accurate temperature control system that fully utilizes the strengths of each can be realized.

In particular, the use of an accelerating/decelerating belt transmission for the mechanical part sufficiently absorbs the startup impact of the large inertia fan and the stress caused by the speed difference between the fan and the electric motor that occurs when deceleration control commands are issued. It is advantageous for controlling ventilation fans because it can achieve continuous duty and can be made smaller. In addition, since the pilot electric controller is connected to this belt transmission, from the perspective of the control system, the speed-up/deceleration type belt transmission can be integrated into one operating end.
As a result of achieving remote automatic control using a servo controller in an almost ideal configuration, temperature control using a blower fan, which was previously considered impossible, has become a reality.
For example, the temperature control on the condenser side of a large-capacity refrigerator can be stabilized, resulting in highly efficient operation of the refrigerator itself and energy savings, and its derivative industrial value is extremely large.

[Brief explanation of the drawing]

Figure 1A shows a configuration diagram of a case where a blower device, which was conventionally considered as a mere idea, is applied to a cooling tower, and Figure 1B shows a partial cross-sectional view of an example of a stepless reducer used there. Fig. 2 shows a schematic external view of a cooling tower according to an embodiment of the present invention, Fig. 3 shows a partial sectional view of an increase/decrease type belt transmission used in the cooling tower, and Fig. 4 shows the same. FIG. 5 shows a wiring diagram of a servo control circuit system for controlling a blower motor for a cooling tower and a belt transmission thereof, and FIG. 5 shows a schematic diagram of a partial configuration of a cooling tower according to another embodiment of the present invention. . In the figure, 10...Cooling tower, 21...Blower fan, 22
...constant speed ratio reducer, 27...main blower motor, 28...increase/deceleration type belt transmission, 29...pilot electric controller, 51...input rotating shaft, 52...intermediate rotating shaft, 70
... Servo adjustment circuit, 80 ... Start/stop control circuit, 8
1...Low temperature section control circuit.

Claims (1)

[Scope of Claims] 1. A temperature control device that adjusts a control medium of a load device to a predetermined temperature by changing speed with a continuously variable transmission, comprising: a temperature detector for a control medium regulated by the load device; An automatic control regulator that supplies a proportional output signal of a predetermined speed ratio to the pilot electric controller in response to a temperature signal of the , an increase/decrease type belt transmission having the pilot electric controller directly connected to one of the sliding pulleys of the pulley device and controlling the speed change by moving the sliding pulley up and down with respect to the fixed pulley; A temperature control device comprising a first feedback closed loop formed by a speed reducer that transmits rotational power of an intermediate shaft to the load device, and the load device. 2 The pilot electric controller controls the speed ratio of the pulley device according to the forward and reverse operations of the reversible motor, and the automatic control regulator transmits the rotational output of the reversible motor to the automatic 2. A temperature control device according to claim 1, further comprising a servo regulator forming a second feedback circuit connected to an input circuit of the control regulator. 3. The automatic control regulator is configured such that the load device is a blower fan, and when the blower fan is stopped, the regulator prevents a speed change command from being sent to the pilot electric controller, forcibly supplies a deceleration command, and 3. The temperature control device according to claim 2, further comprising a start/stop control circuit that stops rotation of the blower fan only in a deceleration state. 4. The automatic control regulator has a start/stop control circuit that stops the blower fan when the control medium is overcooled and starts it when the fan returns to normal.
Temperature control device as described in section.