Pump apparatus

Abstract

Provided is a pump apparatus capable of improving the performance in a wide operation range from an operation area with a low pressure and a high flow rate to an operation area with a high pressure and a low flow rate while suppressing a rated output of a motor used to drive a pump. A rotation speed of a motor 20 is controlled so that the rotation speed of the motor decreases with an increase in the load of the motor 20 driving a pump unit 10 , the rotation speed thereof increases with a decrease in the load thereof, and the load does not exceed a predetermined upper limit. For this reason, it is possible to improve the performance in a wide operation range from an operation area with a low pressure and a high flow rate to an operation area with a high pressure and a low flow rate compared to a method of the related art of uniformly keeping a rotation speed of a motor.

What is claimed is: 
     
         1 . A pump apparatus comprising:
 a pump;   a motor that drives the pump;   a rotation speed detector that detects a rotation speed of the motor;   a rotation speed controller that controls the rotation speed of the motor so that the rotation speed detected by the rotation speed detector approaches a target rotation speed;   a load detector that detects a load of the motor; and   a target rotation speed regulator that regulates the target rotation speed in response to the load detection value of the load detector so as to approach a predetermined relation between the load and the rotation speed, the predetermined relation being set so that the rotation speed decreases in accordance with an increase in the load, the rotation speed increases in accordance with a decrease in the load, and an upper-limit value of the load is set,   wherein in a case where the target rotation speed regulator regulates the target rotation speed in response to the load detection value, the target rotation speed regulator calculates a difference between the target rotation speed set to the rotation speed controller and a predetermined rotation speed corresponding to the load detection value in the predetermined relation, and sets a new target rotation speed, which is included in the range from the predetermined rotation speed to the currently set target rotation speed and in which a difference between the new target rotation speed and the predetermined rotation speed is smaller than the calculated difference, to the rotation speed controller when the calculated difference exceeds a predetermined threshold value.   
     
     
         2 . The pump apparatus according to  claim 1 ,
 wherein the target rotation speed regulator sets a middle rotation speed in the range from the predetermined rotation speed to the currently set target rotation speed as the new target rotation speed to the rotation speed controller.   
     
     
         3 . A pump apparatus comprising:
 a pump;   a motor that drives the pump;   a rotation speed detector that detects a rotation speed of the motor;   a rotation speed controller that controls the rotation speed of the motor so that the rotation speed detected by the rotation speed detector approaches a target rotation speed;   a load detector that detects a load of the motor; and   a target rotation speed regulator that regulates the target rotation speed in response to the load detection value of the load detector so as to approach a predetermined relation between the load and the rotation speed, the predetermined relation being set so that the rotation speed decreases in accordance with an increase in the load, the rotation speed increases in accordance with a decrease in the load, and an upper-limit value of the load is set,   wherein the target rotation speed regulator sets a minimum rotation speed defined in the predetermined relation as the target rotation speed to the rotation speed controller when the load detection value exceeds the upper-limit value and the target rotation speed currently set to the rotation speed controller is faster than the minimum rotation speed, and decreases the target rotation speed by a predetermined variation amount until the load detection value becomes smaller than the upper-limit value when the load detection value exceeds the upper-limit value even after the setting.   
     
     
         4 . A pump apparatus comprising:
 a pump;   a motor that drives the pump;   a rotation speed detector that detects a rotation speed of the motor;   a rotation speed controller that controls the rotation speed of the motor so that the rotation speed detected by the rotation speed detector approaches a target rotation speed;   a load detector that detects a load of the motor; and   a target rotation speed regulator that regulates the target rotation speed in response to the load detection value of the load detector so as to approach a predetermined relation between the load and the rotation speed, the predetermined relation being set so that the rotation speed decreases in accordance with an increase in the load, the rotation speed increases in accordance with a decrease in the load, and an upper-limit value of the load is set,   wherein in a case where the target rotation speed regulator regulates the target rotation speed in response to the load detection value, the target rotation speed regulator increases the target rotation speed until a difference between the load detection value and the upper-limit value becomes smaller than a predetermined threshold value when the target rotation speed currently set to the rotation speed controller is slower than the minimum rotation speed defined in the predetermined relation, the load detection value is smaller than the upper-limit value, and the difference between the load detection value and the upper-limit value exceeds the threshold value.   
     
     
         5 . The pump apparatus according to  claim 1 ,
 wherein the pump is a self-priming pump, and   wherein the target rotation speed regulator sets a target rotation speed for a self-priming operation faster than a maximum rotation speed defined in the predetermined relation to the rotation speed controller when receiving a signal for instructing the start-up of the pump.   
     
     
         6 . The pump apparatus according to  claim 5 ,
 wherein the target rotation speed regulator compares the load detection value with a predetermined lower-limit value after setting the target rotation speed for the self-priming operation to the rotation speed controller, and regulates the target rotation speed in response to the load detection value when the load detection value exceeds the lower-limit value.   
     
     
         7 . The pump apparatus according to  claim 6 ,
 wherein the target rotation speed regulator stops the rotation of the motor when the load detection value is smaller than the lower-limit value for a predetermined time after the target rotation speed for the self-priming operation is set to the rotation speed controller.   
     
     
         8 . The pump apparatus according to  claim 6 ,
 wherein the target rotation speed regulator sets an initial target rotation speed slower than the target rotation speed for the self-priming operation to the rotation speed controller when receiving a signal for instructing the start-up of the pump, compares the load detection value with the lower-limit value after the setting, and sets the target rotation speed for the self-priming operation to the rotation speed controller when the load detection value is smaller than the lower-limit value.   
     
     
         9 . A pump apparatus comprising:
 a pump;   a motor that drives the pump;   a rotation speed detector that detects a rotation speed of the motor;   a rotation speed controller that controls the rotation speed of the motor so that the rotation speed detected by the rotation speed detector approaches a target rotation speed;   a load detector that detects a load of the motor; and   a target rotation speed regulator that regulates the target rotation speed in response to the load detection value of the load detector so as to approach a predetermined relation between the load and the rotation speed, the predetermined relation being set so that the rotation speed decreases in accordance with an increase in the load, the rotation speed increases in accordance with a decrease in the load, and an upper-limit value of the load is set.