JP3142267B2 - Pump device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump device for pumping liquid used for air conditioning, water supply equipment or a refrigerator, and more particularly, to a pump in which two or more constant speed pumps without rotation speed control are arranged in parallel. Related to the device.

[0002]

2. Description of the Related Art FIG. 9 shows a conventional example in which two so-called single-speed pumps 1 and 2 whose rotational speeds cannot be changed are arranged side by side as constant-speed pumps. 4
Into a common discharge pipe 5 and communicate with a load generating section 9 where the load changes, such as a heat exchange section of an air conditioner.

FIG. 10 is a diagram showing the operating state of the pump device shown in FIG. 9, in which the vertical axis H is the head (discharge pressure), the horizontal axis Q is the discharge amount (water amount), and the curve P1 is the head when one unit is operating. Curve, P1 +
P2 is a lift curve when the two units are operated, and curve R is a line resistance curve planned based on the rated discharge amount 2Qn when the two units are operated. The pump device is operated along the line resistance curve R. . When two units are operating as planned, the pump operating point is B. If this is changed to one unit, the point A intersecting with the head Hn on the curve P1 becomes the rated operating point, and the pump power, overload, etc. No problem arises.

[0004]

In FIG. 10, when the load is reduced from the two-unit operation state to the one-unit operation, the pump operation point is the intersection A1 between the pipeline resistance curve R and the curve P1. . The water amount Q1 at the operating point A1 is equal to the rated operating point A
Since the water amount is much larger than the water amount Qn, the operation state becomes an excessive water amount, and the possibility that the pump power is overloaded is very high.

In order to prevent the above-mentioned overload of the pump power, the valve at the pump outlet is throttled down to a range where the overload is not overloaded. In this case, the pump characteristic on the valve secondary side is shown by a broken line. It becomes like curve P1 ',
The amount of water Qn at the rated operating point A will be insufficient. In order to compensate for this water shortage and prevent the overload from occurring, a large-sized motor whose output is one rank or several ranks is generally adopted as the motor for driving the pump. However, when a large motor is used, the equipment for controlling the motor is similarly increased in size, which not only increases the equipment cost but also increases the flow rate and lowers the pump efficiency. It also causes cavitation and noise and vibration.

FIG. 11 shows a conventional example in which the above-described parallel type pump device is applied to a refrigerator. Two constant speed type pumps 1 and 2 arranged in parallel are connected to a suction header tube 24 having a common suction side. The discharge sides are refrigerators 21 and 22, respectively.
, And the two refrigerators 21 and 22 join the common discharge header tube 23. The discharge header tube 23 is a common tube 2
9 is connected to a common secondary load generator 28, the outlet of which is connected to the return header tube 26 and further returned to the suction header tube 24 via the flow rate sensor 30. It is configured to be. The suction header tube 24 and the discharge header tube 23 share a line resistance other than the individual lines of the pumps 1 and 2.

[0007] Generally, the operation of the refrigerator is stopped when the amount of chilled water is reduced to a certain limit, in order to prevent internal freezing and a drastic decrease in refrigeration efficiency even when the load on the secondary load generating unit is reduced. By operating the relay, the operation of the refrigerator is stopped. Therefore, as shown in FIG. 11, a bypass pipe 2 is provided between the discharge header pipe 23 and the return header pipe 26.
The operation of the pump on the heat source side including the refrigerator and the refrigerator 7 is often a so-called quantitative operation in which the pump device is rated and operated by bypassing the discharge header tube 23 and the return header tube 26. However, with the bypass structure as described above, regardless of the magnitude of the load,
Operation with a lot of energy loss is forced and fuel cost is increased.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pump device in which two or more constant speed pumps are arranged side by side, so that a constant flow rate operation can be reliably performed even when the load is reduced, and the above-mentioned adverse effects due to an excessive flow rate are prevented. It is. Another object of the present invention is to provide a pump device which can eliminate inefficiency due to a conventional bypass system in a refrigerator or the like and can perform energy-saving operation without increasing the size of a motor.

In order to achieve the above object, the invention according to claim 1 of the present application comprises a plurality of constant-speed pumps 1 and 2 having a fixed rotation speed in parallel, and a discharge unit 1 of each of the pumps 1 and 2.
a, 2a are connected to a common load generating section 9 (or 28) via discharge pipes 3, 4 and a common discharge pipe 5 in which these are assembled, and discharge sections 1a, 2a of the pumps 1, 2 or the primary side. The discharge pipe portions 3a, 4a are connected to the primary valve portions of the two-way valves 11, 12 for controlling the primary pressure of the valve to a constant pressure, and the secondary outlets of the two-way valves 11, 12 are connected. Is connected to the load generating unit 9 side. As a result, the pump can be operated at a constant flow rate, and the above-mentioned adverse effects due to an excessive flow rate can be prevented. Further, the present invention can be implemented simply by connecting a two-way valve of a constant primary pressure control type to the pump, and the cost of parts can be reduced.

According to a second aspect of the present invention, in the pump device of the first aspect, the two-way valve is capable of changing a setting of a primary side set pressure to a value other than a specified pump head.

According to a third aspect of the present invention, in the pump device according to the first aspect, each pump is provided with a two-way valve of a primary pressure constant control type, and the primary set pressure is changed to a different value for each pump. It is characterized by being possible.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The pump device shown in FIG. 1 is a chilled / hot water pump device for an air conditioner to which the present invention is applied.
Two constant speed pumps 1 and 2 are provided side by side. As the constant-speed pumps 1 and 2, so-called single-speed pumps whose rotation speeds are not changed and controlled are used, but variable-speed pumps having fixed rotation speeds can also be used.

Discharge pipes 3 and 4 are respectively connected to the discharge ports 1a and 2a of the constant-speed pumps 1 and 2, and both discharge pipes 3 and 4 merge into a common discharge pipe 5. Flow sensor 6
Are connected to a common load generating unit 9, for example, a heat exchange unit.

Two-way valves 11 and 12 having a primary side pressure constant control function are disposed in the discharge pipes 3 and 4 or the discharge ports 1a and 2a of the constant speed pumps 1 and 2, respectively. Although the two-way valves 11 and 12 are connected to both pumps 1 and 2 in FIG.
When one of the constant-speed pumps 1 is the starting and the other constant-speed pump 2 is the late, and their operation order is fixed, the two-way valve 11 is connected to the preceding constant-speed pump 1. It is possible to omit the two-way valve 12 of the later constant-speed pump 2. As the two-way valves 11 and 12, a normal electric control valve, a pneumatic control valve, a hydraulic control valve, or a self-control valve using hydraulic power is suitable, and the primary pressure of the valves 11, 12 is controlled to a constant pressure. It has the function to do. In other words, it has a function of controlling the pressures of the discharge ports 1a and 2a of the constant speed pumps 1 and 2 and the primary discharge pipe portions 3a and 4a of the discharge pipes 3 and 4 to a constant pressure.

FIG. 3 is a head curve diagram showing the operating state of one of the pump devices of FIG. 1 (operating state of only the preceding constant speed pump 1), wherein the vertical axis H is the head and the horizontal axis Q is the discharge. Amount (amount of water)
And the total pump head is equal to the discharge pressure.
Curve P1 is the lift curve of the pump 1. When the primary side set pressure of the two-way valve 11 is Hn and the rated discharge amount is Qn, the point (Qn, Hn) is the rated operating point A, and the rated operating point is The pipeline resistance curve passing through A is denoted by Rfn, and those with sequentially reduced pipeline resistance are denoted by Rf1, Rf2, and Rf3 in order from the largest one.

If the line resistance (load) is reduced to the curve Rf1 during the operation at the rated operating point A, the pump operating point will be at the intersection A1 between the curve Rf1 and the curve P1 if no control is applied. And the pump discharge pressure drops to the pressure corresponding to the point A1. However, when the two-way valve 11 is provided as in the present invention and the primary pressure of the valve 11 is controlled to a constant pressure, the pump discharge pressure, that is, the two-way valve 1
By detecting a decrease in the primary pressure, the throttle amount inside the two-way valve is automatically increased, and the primary pressure is increased to the pressure Hn corresponding to the rated operating point A. The amount of increase in the throttle of the two-way valve 11 at this time is equal to the difference between the line resistance curve Rfn and the same Rf1. Therefore, the pump performance (secondary pressure) imagined at the two-way valve outlet is determined by the pump head From the curve P1,
The difference between the resistance curve Rfn and the resistance curve Rf1 is subtracted for the entire discharge amount, and the result is a lift curve P1-1 indicated by a broken line.
Therefore, the intersection point An1 between the curve P1-1 and the pipeline resistance curve Rf1 is the operating point of the virtual pump performance at the two-way valve outlet, and the discharge amount at this time is Qn, which is the same as the rated operating point A. Discharge amount.

Since the original operating point of the pump in this state is nothing but the point A, the pump continues to operate at the same operating point A as the original even if the secondary line resistance changes. become.

Subsequently, when the pipe resistance decreases and the curve Rf2 is reached, the primary pressure of the two-way valve 11 decreases to the point A2, so that the throttle amount of the two-way valve 11 further increases, and The aperture is adjusted to A. The operating point at this time is represented by curve R
Same as f1. That is, two-way valve outlet (secondary side)
Is a curve P1-2, the intersection An2 of the curve P1-2 and the curve Rf2 is a virtual operating point,
The discharge amount at this time is Qn, which is the same discharge amount as the rated operating point A. Of course, the original operating point of the pump at this time is point A, as in the case of the curve Rf1.

Further, even when the pipe line resistance further decreases and becomes the curve Rf3, as in the case of the curves Rf1 and Rf2, the operating point of the virtual pump performance is An3, the original operating point of the pump is A, and the discharge is The amount becomes Qn, and in any case, as a result of controlling the primary pressure to be constant by the two-way valve, the pump discharge amount is maintained at the constant value Qn. That is, it is understood that the constant flow rate operation is performed.

FIG. 2 is a view showing a state in which two constant-speed pumps are operated in parallel. As in FIG.
The primary side set pressures of the two-way valves 11 and 12 are set to the same Hn, and a curve P1 + P2 is a lift curve when two units are operated. Here, when the flow rate decreases from 2Qn to Qn, as described above, the pump outlet side, that is, the primary pressure of the two-way valve 11 also decreases, so the two-way valve 11 increases the internal throttle to reduce the pressure Hn. Try to keep. As a result, the pump discharge pressure is maintained at the pressure Hn. If the resistance of the two-way valve 11 when fully opened is ignored, the resistance to the curve P1 when the two-way valve 11 is fully opened is represented by a curve R1.
However, when the flow rate gradually decreases, the two-way valve 11 increases the internal throttle in order to prevent a decrease in the primary pressure. When one pump is operated, the increase in the throttle becomes a curve r, and the pump 1 operates at the intersection A between the curve P1 and the curve r. On the secondary side of the two-way valve 11, the virtual pump performance becomes a curve P1-n obtained by subtracting the valve resistance increase r from the curve P1, and the intersection A of the curve P1-n and the curve R is obtained.
n becomes the operating point of the virtual pump performance, and the discharge amount becomes Qn. That is, by designating the primary side set pressure of the two-way valve 11 as Hn, the advance pump 1 is operated with the discharge amount Qn fixed, and the operating point A1 as in the conventional example of FIG. The excessive discharge amount Q1 can be avoided.

As described above, in the parallel operation of two constant-speed pumps 1 and 2, conventionally, when one pump is stopped, the remaining one rotates at a discharge rate greatly exceeding the rating,
Although various problems such as an overload or an increase in vibration noise occur, as in the present invention, the two-way valve 11 of the primary pressure constant control type is arranged at least at the discharge part of the constant-speed pump P1 which has been developed earlier. By controlling the primary pressure to be constant, the pump 1 is operated at the rated water volume Qn, and the above problem does not occur.

[0022]

[Embodiment 2] FIG. 4 shows an apparatus in which constant-speed pumps 1 and 2 are connected to refrigerators 21 and 22, respectively, to which the invention described in claim 2 of the present application is applied. The basic structure is the same as that of the device shown in FIG. 11, and the same components are denoted by the same reference numerals and overlapping description will be omitted.

The discharge sections of the constant speed pumps 1 and 2 are provided with two-way valves 11 and 12 of a constant primary pressure control type, respectively.
The primary pressure (pump discharge pressure) of the two-way valves 11, 12 is controlled to be constant, and the two-way valves 11, 12
Reference numeral 12 indicates that the set pressure can be changed to a value other than the specified pump head Hn.

FIG. 5 shows the operating state of one constant speed pump. The horizontal axis shows the flow rate Q in%, and the vertical axis shows the head (pump pressure) H in%. P1 is pump 1
Is a curve representing the pipeline resistance, and the intersection A of the curves P1, R indicates the rated operating point of the pump 1. The rated water amount Qn is set to 100%, and the lower limit water amount Qb of the refrigerator is set to, for example, 60%. Hn is 100% ratio
Hb is the head corresponding to the water amount Qb,
For example, the ratio is 130%.

As the load on the secondary load generator 28 decreases,
When the amount of water gradually decreases from Qn to Qb, two-way valve 1
If the primary side set pressure of 1, 12 is designated as Hb, the pump operating point is A4, the secondary virtual pump performance of the two-way valve 11 is P1-n, and the virtual pump performance operating point is Ab, whereby the ejection amount is fixed at Qb.

As described above, the refrigerator lower limit water amount Qb is reliably maintained at the set value irrespective of the continuous decrease in the load. In addition, compared to the conventional bypass-type fixed operation, the power is reduced according to the load. For example, L indicates a change in pump power (shaft power). In the conventional quantitative operation, the shaft power is required to be L1, whereas in the present application, L2 is reduced.

In short, if the two-way valves 11 and 12 can be changed to a set pressure other than the specified head, in the refrigerator shown in FIG. By variably setting the two-way valves 11 and 12 so that the pressure becomes a pressure (%) corresponding to each water amount, the lower limit water amount of the refrigerator is ensured at any time, and at the same time, the operation is performed according to a decrease in the flow rate. By using the pump characteristic that reduces the power, it is possible to achieve energy saving compared to the conventional quantitative operation.

Further, FIG. 6 explains that the pump can be operated at a pressure corresponding to the discharge amount of the pump by controlling the two-way valves 11 and 12 in a small water amount equal to or less than the rated water amount Qn.

When the cooling load is reduced, the pipe resistance is increased by a method such as increasing the amount of chilled water supplied to the air conditioner by using a regulating valve to increase the throttle, and the resistance curve r1 becomes larger than the resistance curve R. If the amount of water at this time is Qb, the pressure on the pump characteristic is Hb, and the intersection of the curve r1 and the pump head P1 is A4. In order to set and maintain such a state, the set pressure of the two-way valves 11 and 12 may be designated as Hb. Then, the pump characteristic imagined on the valve secondary side at this time is a curve P1-1 obtained by subtracting the difference between the curve R and the curve r1 from the curve P1 over each water amount. Then, an intersection An1 between the curve P1-1 and the curve R is a virtual pump operating point. This means that the operation at the virtual operating point An1, that is, the water amount Qb, is guaranteed unless the set pressure Hb is changed once. Further, when the load water amount is reduced to Qc, the two-way valves 11, 12
As long as the primary side pressure is indicated as Hc, the pump operating point is A5, the virtual pump performance is curve P1-2, the virtual pump operating point is An2, and the water amount Qc is discharged.

That is, when the water amount Qc is set to the lower limit water amount, if the primary side set pressure of the two-way valves 11 and 12 is designated to the pressure Hc corresponding to the water amount, the water amount Qc cannot be reduced below this water amount Qc. Therefore, the minimum water volume required for the refrigerator is secured.

By setting the corresponding pump pressure in advance from the water amounts Qn to Qc in FIG. 6, the rated water amount Q
In the range from n to the lower limit water amount Qc, the two-way valve 1
The primary set pressures of the first and the second 12 are automatically changed, so that a reliable operating state can be maintained. And the lower limit water amount can be surely kept.

[0032]

Third Embodiment In FIG. 7, four constant-speed pumps 41, 42, 43, and 44 are provided side by side.
A case where the invention according to claim 3 of the present application is applied to a pump device in which two-way valves 51, 52, 53, 54 of a constant primary pressure control type are connected to discharge portions 42, 43, 44 will be described. That is, the setting pressure of each of the two-way valves 51, 52, 53, 54 can be changed to a different value for each pump.

FIG. 8 shows a head curve in the four-unit operation state of the pump device of FIG. In the single-unit operation, the operating point when there is no two-way valve 51 is A1, but in the present application, the operating point of the virtual pump performance is An due to the primary side constant pressure control of the two-way valve 51, and the discharge amount is It becomes the rated Qn, and the pump discharge pressure is kept at Hn.

Similarly, during the operation of the two vehicles, as described above,
The operating point when the two-way valve 52 is not provided is B1, but in this application, the operating point of the virtual pump performance is Bn, the discharge amount is 2Qn, and the pump discharge pressure is Hn is maintained.

During the operation of the three units, the operating point when there is no two-way valve 53 is C1 as described above. The point is Cn, the discharge amount is kept at 3Qn, and the pump discharge pressure is kept at Hn.

During operation of all four units, all pumps are rated. As described above, no matter how many units are operated in parallel, if the primary pressure of the two-way valve is set to the pressure corresponding to the rated discharge amount of the pump at that time, the pump will be operated at a constant rated water volume, Excessive water operation or overload operation does not occur.

Further, if the necessary pressure is set in advance in accordance with the change between the water amounts, the required pressure is automatically set for the two-way valve in each state with respect to the continuous change in the water amount. Therefore, a reliable pump discharge amount can be obtained without excess or shortage over the entire water amount range. In FIG. 8, the upper and lower limits of the pressure at this time are as follows. In FIG. 8, the set pressure at the time of minimum water flow is Hs and the set pressure at the maximum water flow is Hn. Time set pressure is Hn
When three units are operated, the set pressure at the minimum water amount is H2, and the set pressure at the maximum water amount is Hn. When four units are operated, the set pressure at the minimum water amount is H3 and the set pressure at the maximum water amount is Hn. The pressure between the maximum and minimum pressures may be set as a pressure approximating the pump head curve.

[0038]

According to the present invention, (1) a plurality of constant-speed pumps are arranged side by side,
In a pump device in which discharge pipes of respective pumps are merged and connected to a common load generating unit, a two-way valve for controlling the primary pressure to a constant level is provided at the discharge unit of the pump. Even in the case of the platform operation state, it is possible to prevent the flow rate from becoming excessively large and prevent the pump power from being overloaded.

(2) It is possible to efficiently use a small pump and prevent overload of the pump power without increasing the size of an electric motor for driving the pump, so that equipment costs can be reduced, and cavitation and noise can be reduced. Generation of vibration can also be prevented.

(3) If the two-way valve can be changed to a set pressure other than the specified head, for example, in the refrigerator,
In response to the change from 00% to the lower limit water amount, the two-way valve is variably set so that the pump pressure becomes a pressure corresponding to each water amount, thereby ensuring the lower limit water amount of the refrigerator at any time, By using the pump characteristic in which the operating power decreases as the flow rate decreases, energy saving can be achieved as compared with the conventional quantitative operation.

(4) If the set pressure of each two-way valve can be changed to a different value for each pump, the primary pressure of the two-way valve can be adjusted to the rated pressure of the pump no matter how many units are operated in parallel. If the pressure is set to the pressure corresponding to the discharge amount, the pump is operated at a constant rated water amount, and there is no excessive water amount operation or overload operation state.

[Brief description of the drawings]

FIG. 1 is a schematic piping diagram of a pump device to which the present invention is applied.

FIG. 2 is a head curve diagram of the pump device of FIG.

3 is a lift curve diagram showing a state of one pump device of FIG. 1 during operation.

FIG. 4 is a schematic diagram of a piping in which the invention described in claim 2 of the present application is applied to a refrigerator.

FIG. 5 is a head curve diagram when one pump device of FIG. 4 is operated.

6 is a head curve diagram when two pump devices of FIG. 4 are operated.

FIG. 7 is a schematic piping diagram of a pump device to which the invention described in claim 3 of the present application is applied.

8 is a head curve diagram showing an operation state of the pump device of FIG.

FIG. 9 is a schematic diagram of a conventional pipe.

FIG. 10 is a lift curve diagram showing an operating state of two pump units of FIG. 9;

FIG. 11 is a piping schematic diagram of a conventional refrigerator.

[Explanation of symbols]

1,2,41,42,43,44 Constant-speed pump 9,28 Common load generator 11,12,51,52,53,54 Two-way valve with constant primary pressure control

Claims (3)

(57) [Claims] 1. A plurality of constant-speed pumps 1 and 2 having a fixed rotation speed are provided in parallel, and discharge sections 1a and 2a of each of the pumps 1 and 2 collect discharge pipes 3 and 4 and these. Connected to the common load generating section 9 (or 28) via the common discharge pipe 5, the discharge section 1a, 2a or the primary discharge pipe section 3a, 4a of each of the pumps 1 and 2 applies a valve primary pressure to a constant pressure. The two-way valves 11 and 12 are connected to the primary side of the constant-pressure control type two-way valves 11 and 12, and the outlets of the two-way valves 11 and 12 are connected to the load generator 9 side. Pumping equipment. 2. The pump device according to claim 1, wherein the two-way valves 1 and 2 are capable of changing a primary side set pressure to a value other than a specified pump head. 3. The pump apparatus according to claim 1, wherein each of said two-way valves 1 and 2 is changeable to a value other than a specified head which can be changed to a different value for each pump.