JP6313827B2 - Non-pulsating pump - Google Patents

Description

  The present invention relates to a reciprocating pump, and more particularly to a structure of a non-pulsating pump having a constant discharge flow rate.

  A pulsating pump composed of a plurality of, usually two (two-series) or three (three-series) reciprocating pumps is used. For example, the duplex type includes a common suction pipe, a discharge pipe, and a drive device including a camshaft and a motor, and the plunger of each pump is set to a predetermined phase difference (in this case, via an eccentric drive cam). , 180 ° phase difference), and two reciprocating pumps configured to be driven. By combining the discharge flow rates of the two pumps, the combined discharge flow rate is configured to be constant at all times, that is, pulsation is achieved.

  However, in such a pulsating pump, it is inevitable that air enters the liquid contact part or the hydraulic drive part. For this reason, even if the plunger is actuated, it takes time for the mixed air to be compressed and reach the discharge pressure at the discharge start point, while at the suction start point, the air expands to the suction negative pressure. It takes time to reach. For this reason, when the transition is made from the suction stroke to the discharge stroke, a discharge delay and a loss in the discharge flow rate occur. Further, in this type of pump, generation of mechanical play in the drive unit is inevitable. For this reason, the movement of the plunger is delayed by the amount of the clearance, the discharge delay due to the mechanical clearance, and the loss of the discharge flow rate occur.

  As described above, in this type of conventional non-pulsating pump, discharge delay and discharge flow rate deficiency due to air mixing and mechanical play occur, so that accurate non-pulsation cannot be achieved.

  For this reason, it is possible to set the shape of the drive cam so as to additionally discharge the replenishment amount with respect to the discharge flow rate deficit in the stroke immediately before shifting to the discharge stroke, correct the discharge flow rate deficiency, and improve the non-pulsation characteristics. It has been proposed (see, for example, Patent Document 1).

  In addition, the cam shape is such that the flow rate of additional discharge immediately before the discharge stroke is greater than the maximum value of the missing discharge flow rate, and it is configured so that excessive additional discharge is discharged from the air vent valve. It has also been proposed to improve the characteristics (for example, see Patent Document 2).

Japanese Patent Laid-Open No. 7-119626 JP-A-8-114177

  However, in the conventional non-pulsating pump as described in Patent Document 1, the missing portion of the discharge flow rate changes due to the change in the set pressure, which is the discharge pressure set when the pump is operated. Here, the set pressure is specifically a pressure obtained by adding the pressure loss of the pipe to the pressure of the load. For example, when the set pressure is high, the volume reduction of the mixed air increases, so it takes time to reach the set pressure and the loss of the discharge flow rate also increases. On the other hand, when the set pressure is low, the missing portion of the discharge flow rate becomes small. For this reason, in the non-pulsating pump described in Patent Document 1, pulsation occurs due to the flow rate of additional discharge being greater than the missing portion of the discharge flow rate due to the set pressure of the pump, or conversely the flow rate of additional discharge is There has been a problem that pulsation occurs when the discharge flow rate becomes smaller than the deficient amount.

  In addition, the conventional pulsation pump described in Patent Document 2 solves the problems of the conventional pulsation pump described in Patent Document 1, but manually operates the air in response to changes in the set pressure. It is necessary to adjust the flow rate discharged from the drain valve, or to replace it with a regulating valve having a different discharge capacity, which is troublesome to handle and takes time for adjustment.

  Accordingly, an object of the present invention is to suppress the occurrence of pulsation by a simple method even when the set pressure changes.

The non-pulsating pump according to the present invention has a rotating cam that converts the rotational motion of a common motor into a plurality of reciprocating motions having a predetermined phase difference, and the plurality of reciprocating pumps are rotated at a predetermined phase difference via the rotating cam. A total including the pre-compression stroke for driving and stopping the plunger after moving the plunger of the reciprocating pump to the discharge side by a minute amount after the suction stroke and before the discharge stroke, and flowing out to the common discharge pipe A non-pulsating pump having a constant discharge flow rate, comprising: a pressure sensor that detects the pressure of the discharge pipe; and a control unit that adjusts the number of rotations of the motor, the control unit being detected by the pressure sensor when the said pressure of the discharge pipe in the precompression stroke is higher than the pressure of the discharge pipe in the discharge stroke detected by said pressure sensor, a reduction in the rotational speed of the motor during the next pre-compression stroke opens By earlier by a predetermined angle from the rotation angle of the rotary cam to start the reduction in the rotational speed of the motor in the pre-compression stroke of a rotation angle ahead of the rotating cam, the rotation of the motor during precompression stroke The rotation speed reduction period in which the number is reduced from the predetermined rotation speed is sequentially increased for each preliminary compression stroke, and the rotation speed of the motor is reduced at a predetermined change rate during the rotation speed reduction period. Is reduced, and the rotational speed is increased at the predetermined change rate to obtain the rotational speed before the start of reduction at the end of the preliminary compression stroke .

In the non-pulsating pump of the present invention, the control unit is configured such that the pressure of the discharge pipe during the previous pre-compression stroke detected by the pressure sensor is lower than the pressure of the discharge pipe during the discharge stroke detected by the pressure sensor. In this case, the rotation angle of the rotating cam which starts the reduction of the rotation speed of the motor during the next preliminary compression stroke is changed to the rotation angle of the rotation cam which starts the reduction of the rotation speed of the motor during the previous preliminary compression stroke. Further, the rotational speed reduction period in which the rotational speed of the motor is reduced from the predetermined rotational speed during the pre-compression stroke may be shortened sequentially for each pre-compression stroke by making the predetermined angle slower. .

In the pulsating pump of the present invention, the predetermined change rate in the reduction of the rotational speed of the motor is such that the discharge flow rate is reduced in the pre-compression stroke after the rotational speed is reduced while the rotational angle of the rotary cam is changed by a predetermined angle. The rotation speed may be changed by the maximum reduction amount that does not cause a defect .

  The present invention can suppress the occurrence of pulsation by a simple method even when the set pressure changes.

It is a systematic diagram which shows the structure of the non-pulsation pump in embodiment of this invention. It is a graph which shows the time change of the plunger speed and total discharge flow rate of the pulsation pump shown in FIG. It is a graph which shows the time change of the plunger position of the pulsation pump shown in FIG. It is a graph which shows the time change of the discharge pressure of the non-pulsating pump shown in FIG. 1 when setting pressure P ^* is the same as design pressure Pd. It is a graph which shows the time change of the discharge pressure of the non-pulsating pump shown in FIG. 1 when setting pressure P ^* is smaller than design pressure Pd. It is a flowchart which shows operation | movement of the pulsation pump shown in FIG. It is a graph which shows the change of the discharge pressure immediately after a pump start, the change curve of the plunger speed during a pre-compression stroke, and the change of motor rotation speed. FIG. 5 is a graph showing a change in discharge pressure, a change curve in plunger speed, and a change in motor rotation speed during the next pre-compression stroke of FIG. 4. It is a graph which shows the change of the discharge pressure in the next precompression process of FIG. 5, the change curve of plunger speed, and the change of motor rotation speed. It is a graph which shows the change of the discharge pressure in the next precompression process of FIG. 6, the change curve of plunger speed, and the change of motor rotation speed. It is a graph which shows the change of the discharge pressure in the preliminary | backup compression process when the setting pressure P ^* becomes high in the state which hold | maintained the change curve of the plunger speed shown in FIG. 7, and the change of motor rotation speed. It is a graph which shows the change of the discharge pressure, the change curve of a plunger speed, and the change of a motor rotation speed in the precompression stroke when the rotation angle which reduces the rotation speed of a servomotor from the state shown in FIG. 8 is delayed.

  Hereinafter, the non-pulsating pump 100 of this embodiment is demonstrated, referring drawings. As shown in FIG. 1, a pulsating pump 100 according to this embodiment includes a frame 10 and a special-shaped rotation attached to a common camshaft 13 that is disposed at the center of the frame 10 and is driven to rotate by a servo motor 11. First and second pumps 20 and 40 that are reciprocating pumps including a cam 15 and plungers 26 and 46 that reciprocate with a phase difference of 180 ° by the rotating cam 15, and a controller that adjusts the rotational speed of the servo motor 11. 70. The servo motor 11 is a motor that can output an angle signal of the rotation angle φ of the shaft 12. In this embodiment, the shaft 12 of the servo motor 11 and the cam shaft 13 are directly connected, and the rotation angle φ of the cam shaft 13, that is, the rotation angle φ of the rotation cam 15 and the rotation angle φ of the shaft 12 of the servo motor 11. However, if the servo motor 11 can detect the rotation angle φ of the cam shaft 13, that is, the rotation angle φ of the rotary cam 15, the shaft 12 of the servo motor 11 and the cam shaft 13 are directly connected. Not necessary.

  As shown in FIG. 1, the rotary cam 15 is a disc-shaped cam that is fixed to the camshaft 13 that is rotationally driven by the servomotor 11, and its tip is fixed to the plunger shaft 28 of the first pump 20. It is sandwiched between two rollers 29. The opposite side of the rotating cam is sandwiched between two rollers 49 fixed to the plunger shaft 48 of the second pump 40. When the rotating cam 15 is rotated by the servo motor 11, the rotating cam 15 reciprocates the plunger shafts 28 and 48 with a phase difference of 180 °. FIG. 1 shows a state where the plunger 26 of the first pump 20 is in the pushing position and the plunger 46 of the second pump is in the pulling position. A rotating cam 15 indicated by a broken line in the drawing indicates a position of the rotating cam 15 when the camshaft 13 is rotated by 180 ° from a state indicated by a solid line. The camshaft 13, the rotating cam 15, and the rollers 29 and 49 attached to the plunger shafts 28 and 48 are cam mechanisms that convert the rotating motion of the common servo motor 11 into a plurality of reciprocating motions having a phase difference of 180 °. 16 is configured.

  The first pump 20 includes a hydraulic chamber 22 that stores oil and a pump chamber 25 that sucks and discharges fluid. The hydraulic chamber 22 and the pump chamber 25 are partitioned by a diaphragm 23. The hydraulic chamber 22 houses a plunger 26 that is connected to the plunger shaft 28 and reciprocates in the hydraulic chamber 22 to change the volume of the hydraulic chamber 22. A packing 27 is disposed between the outer peripheral surface of the plunger 26 and the inner peripheral surface of the hydraulic chamber 22 so that the oil in the hydraulic chamber 22 does not leak to the outside.

  A suction pipe 30 that sucks fluid into the pump chamber 25 and a discharge pipe 32 that discharges fluid from the pump chamber 25 are connected to the pump chamber 25 of the first pump 20. In addition, check valves 31 and 33 are attached to the suction pipe 30 and the discharge pipe 32 to prevent backflow of fluid.

  The second pump 40 has the same structure as the first pump 20. In FIG. 1, the same parts as those of the first pump 20 are denoted by reference numerals in the 40's in the same place, and the description thereof is omitted. The suction pipe 50 and the discharge pipe 52 of the second pump 40 are also provided with check valves 51 and 53 in the same manner as the suction pipe 30 and the discharge pipe 32 of the first pump 20.

  As shown in FIG. 1, the suction pipe 30 of the first pump 20 and the suction pipe 50 of the second pump 40 are each connected to a common suction pipe 35. Further, the discharge pipe 32 of the first pump 20 and the discharge pipe 52 of the second pump 40 are respectively connected to the common discharge pipe 36.

  The control unit 70 is a computer including a CPU 71 that performs signal processing and arithmetic processing therein, a memory 72 that stores control programs, control data, and the like, and an interface 73 that exchanges signals with the pressure sensor 63 and the servo motor 11. is there. A signal from the pressure sensor 63 is input to the control unit 70, and the rotation angle φ of the servo motor 11 is also input to the control unit 70. The servo motor 11 is driven by a command from the control unit 70.

In the non-pulsating pump 100 configured as described above, when the rotating cam 15 attached to the camshaft 13 is rotated by the servomotor 11, the plunger shafts 28 and 48 are reciprocated by the rotating cam 15 with a phase difference of 180 °. The fluid in the pump chambers 25 and 45 is alternately discharged to the common discharge pipe 36 to pressure-feed the fluid without pulsation. Hereinafter, the operation of the pulsating pump 100 will be described with reference to FIGS. 2A to 2E. In the following description, the discharge pressure set when the pump is operated will be described as the set pressure P ^* , and the discharge pressure when determining the plunger speed curve with respect to the rotation angle φ in the preliminary compression stroke will be described as the design pressure Pd. As described above, the set pressure is specifically a pressure obtained by adding the pressure loss of the pipe to the pressure of the load.

<Operation of pulsating pump when set pressure P ^* is the same as design pressure Pd>
First, the set pressure P ^*, which is the discharge pressure set in operating the pump, is the same as the design pressure Pd, which is the discharge pressure when determining the plunger speed curve with respect to the rotation angle φ in the pre-compression stroke. The operation of the non-pulsating pump 100 in this case will be described.

  2A, the solid line 82 indicates the speed of the plunger 26 of the first pump 20 with respect to the rotation angle φ of the rotary cam 15, the broken line 83 indicates the speed of the plunger 46 of the second pump 40, and the alternate long and short dash line 81 indicates the first pump. 20 shows a change in the total discharge flow rate of 20 and the second pump 40, that is, the flow rate of the fluid discharged from the common discharge pipe 36. In FIG. 2A, a positive plunger speed indicates that the plunger 26 moves in the direction of discharging fluid from the pump chamber 25, and a negative plunger speed indicates that the plunger 26 moves in the direction of sucking fluid into the pump chamber 25. Indicates.

  In the pulsating pump 100 of the present embodiment, air is inevitably mixed into the hydraulic chambers 22 and 42, and there is a minute play in the drive unit. Therefore, in the pulsating pump 100 of the present embodiment, after the plungers 26 and 46 are slightly moved to the discharge side in the stroke immediately before the transition from the suction stroke to the discharge stroke, the plungers are temporarily stopped and the pressure in the hydraulic chambers 22 and 42 is reduced. It has a pre-compression stroke to preliminarily compress the mixed air bubbles and eliminate the plunger non-working part due to minute play before the start of discharge by changing the movement direction of the plunger, and replenish the discharge flow rate deficiency Yes.

  As shown by a solid line 82 in FIG. 2A, the first pump 20 is configured such that the rotation angle φ of the rotary cam 15 is between −φ0 and 0 °, and the pre-compression stroke, and the rotation angle φ is from 0 ° to the rotation angle φ1. From the discharge stroke, from the rotation angle φ1 to the rotation angle φ2, the resting stroke, from the rotation angle φ2 to (360 ° −φ0) the suction stroke, and from the rotation angle φ (360 ° −φ0), Similar to the above, the pre-compression stroke, the discharge stroke, the pause stroke, and the suction stroke are repeated.

  On the other hand, as indicated by a broken line 83 in FIG. 2A, the second pump 40 is configured to perform a discharge stroke from the rotation angle φ3 to the rotation angle φ4 when the rotation angle φ of the rotary cam 15 is from −φ0 to the rotation angle φ3. The interval is a pause stroke, the suction stroke is between the rotation angle φ4 and the rotation angle φ is (180 ° −φ0), and the precompression stroke and rotation angle is between the rotation angle φ is (180 ° −φ0) and 180 °. The discharge stroke is when φ is 180 ° or later. In the second pump 40, the preliminary compression stroke, the discharge stroke, the pause stroke, and the suction stroke are repeated at an angle where the rotation angle φ of the first pump 20 and the rotary cam 15 is shifted by 180 °.

As shown by the solid line 82 in FIG. 2A, in the first pump 20, in the pre-compression stroke in which the rotation angle φ of the rotary cam 15 is from −φ0 to 0 °, the plunger 26 is rotated by the special-shaped rotary cam 15 by the rotation angle φ3. To the direction in which the fluid is discharged at a minute speed smaller than the steady speed in the discharge stroke when the rotation angle φ is 180 °. When the rotation angle φ becomes 0 °, the movement is stopped. The position of the plunger 26 at this time is shown by a solid line 85 in FIG. 2B. As shown by the solid line 85 in FIG. 2B, the plunger 26 slowly rises from the 0% position (pull position) until the rotation angle φ of the rotary cam 15 is −φ0 to just before the rotation angle φ is 0 °. Once the rotation angle φ of the valve reaches 0 °, the movement of the plunger 26 stops (preliminary compression stroke). Thus, when the plunger 26 moves slowly in the discharge direction, the bubbles in the hydraulic chamber 22 are crushed and the hydraulic pressure in the hydraulic chamber 22 is increased. 2C, when the rotation angle φ of the rotary cam 15 is 0 °, the diaphragm 23 starts moving toward the pump chamber 25, and the pressure P1 in the pump chamber 25 is equal to the common discharge pipe 36. Pressure P3, that is, substantially the same pressure as the set pressure P ^*, and fluid discharge from the pump chamber 25 to the common discharge pipe 36 is started. On the other hand, as indicated by a broken line 83 in FIG. 2A, the second pump 40 starts to decrease the plunger speed and the discharge flow rate from the rotation angle of 0 °. The increase in the discharge amount of the first pump 20 when the rotation angle φ of the rotation cam 15 is 0 ° and the decrease in the discharge amount of the second pump 40 when the rotation angle φ of the rotation cam 15 is 0 ° cancel each other. A constant flow rate of fluid flows through the pipe 36. Further, the pressure P3 of the common discharge pipe 36 is also kept constant at the set pressure P ^* .

  Then, when the rotation angle φ of the rotary cam 15 is from 0 ° to the rotation angle φ3, the speed of the plunger 26 increases at a constant rate and then moves in the discharge direction at a constant speed (discharge stroke). Note that the speed change of the plunger 26 as shown in FIG. 2A is caused by the special-shaped rotary cam 15, and the rotation speed of the servo motor 11 is constant.

  2B, at the rotation angle φ1, the plunger 26 reaches the 100% position (extrusion position) and maintains the 100% position (extrusion position) until the rotation angle φ2 (resting process). Thereafter, as shown by the solid line 82 in FIG. 2A, when the speed of the plunger 26 becomes negative, the plunger 26 moves from the 100% position (extrusion position) toward the 0% position (pull position) toward the opposite side of the pump chamber 25. Move. Thereby, the pressure P1 of the hydraulic chamber 22 and the pump chamber 25 decreases, and the fluid is sucked into the pump chamber 25 (suction stroke). When the rotation angle φ of the rotary cam 15 is (360 ° −φ0), the pre-compression stroke, the discharge stroke, the pause stroke, and the suction stroke are repeated as described above.

  As shown by a broken line 84 in FIG. 2B, the plunger 46 of the second pump 40 has a 0% position (pulling position) where the rotation angle φ of the plunger 26 of the first pump 20 and the rotating cam 15 indicated by a solid line 85 is shifted by 180 °. And 100% position (extrusion position).

In this way, the plunger 26 of the first pump 20 and the plunger 46 of the second pump 40 reciprocate between the 0% position (pulling position) and the 100% position (extrusion position) with the rotation angle φ shifted by 180 °. When the pressure P ^* is the same as the design pressure Pd, the pressure P1 in the pump chamber 25 of the first pump 20 is set to the pressure P3 (set in the common discharge pipe 36) at the end of the preliminary compression stroke (rotation angle φ is 0 °). Since the pressure is substantially the same as the pressure P ^* ), the fluid is discharged from the pump chamber 25 to the common discharge pipe 36 without delay at the same time as the discharge stroke of the first pump is started. Then, the increase in the discharge amount of the first pump 20 when the rotation angle φ of the rotary cam 15 is 0 ° and the decrease in the discharge amount of the second pump 40 when the rotation angle φ of the rotary cam 15 is 0 ° are offset, The total discharge flow rate of the first pump 20 and the second pump 40 is a constant rated flow rate with no pulsation, as shown by a one-dot chain line 81 in FIG. 2A.

<Operation of pulsating pump when set pressure P ^* is lower than design pressure Pd>
As shown in FIG. 2D, when the pressure P3 of the common discharge pipe 36, that is, the set pressure P ^* is lower than the design pressure Pd, the discharge flow rate is small, and the servo motor 11 is operated in the same manner as described above. When the preliminary compression stroke is performed with constant rotation, as shown by the solid line 92a in FIG. 2D, before the preliminary compression stroke ends, for example, when the rotation angle φ of the rotary cam 15 is −φ0 ′, the pump chamber 25 Pressure P1 reaches the pressure P3 (set pressure P ^* ) of the common discharge pipe 36, and fluid is discharged from the pump chamber 25 to the common discharge pipe 36 during the preliminary compression stroke. When the rotation angle φ of the rotary cam 15 is −φ0 ′, the plunger 46 of the second pump 40 moves in the discharge direction at a constant speed as indicated by the broken line 83 in FIG. 2A, and a predetermined flow rate is supplied from the pump chamber 45 to the common discharge pipe. 36 is discharged. For this reason, the flow rate of the fluid flowing in the common discharge pipe 36 is the total flow rate of the fluid flow discharged from the first pump 20 to the constant flow discharged from the second pump 40, and the pressure P3 of the common discharge pipe 36 is As shown by the one-dot chain line 91a in FIG. 2D, the set pressure P ^* is exceeded, and pulsation occurs in the total discharge flow rate.

Therefore, when the set pressure P ^* is lower than the design pressure Pd and the pulsation occurs, the non-pulsating pump 100 of the present embodiment sequentially increases the rotation speed of the servo motor 11 during the preliminary compression stroke from the predetermined rotation speed R0. It is reduced and adjusted so that the pulsation falls within the allowable range. Hereinafter, it will be described in detail with reference to FIGS. First, the operation of the control unit 70 will be described with reference to FIG.

As shown in step S <b> 101 of FIG. 3, the control unit 70 starts the non-pulsating pump 100. Then, the servo motor 11 starts rotating, and the first pump 20 and the second pump 40 repeat the preliminary compression stroke, the discharge stroke, the pause stroke, and the suction stroke with the rotation angle φ shifted by 180 °. Next, as shown in step S102 of FIG. 3, the control unit 70 detects the average pressure P3flat of the common discharge pipe 36 during a period in which the pressure is stable during the discharge stroke, using the pressure sensor 63 shown in FIG. . The period in which the pressure is stable during the discharge pressure stroke is a case where one of the first pump 20 or the second pump 40 is in the discharge stroke, the plunger speed is constant, and the other is in the suction stroke. For example, as shown in FIG. 2A, between the rotation angle φ4 and the rotation angle (180 ° −φ0), the first pump 20 is in the discharge stroke, the speed of the plunger 26 is constant, and the second pump 40 is in the suction stroke. During the period, or in FIG. 2A, the second pump 40 is in the discharge stroke, and the speed of the plunger 46 is constant and the first pump 20 sucks in, such as between the rotation angle φ2 and the rotation angle (360 ° −φ0). It is a period during the process. This average pressure P3flat is a pressure determined by the pressure obtained by adding the pressure loss of the pipe to the load pressure, and is equal to the set pressure P ^* described above.

  Next, as shown in step S <b> 103 of FIG. 3, the control unit 70 detects the maximum pressure P <b> 3 revmax and the minimum pressure P <b> 3 revmin of the common discharge pipe 36 during the preliminary compression stroke by the pressure sensor 63. In this detection, for example, the pressure of the common discharge pipe 36 during the pre-compression stroke is detected at a predetermined interval and stored in the memory 72, and the maximum value and the minimum value are selected from the detected values. Also good.

  Next, as shown in step S104 of FIG. 3, the control unit 70 calculates the absolute value of the difference between the maximum pressure P3revmax and the average pressure P3flat (| P3revmax−P3flat |) or the difference between the minimum pressure P3revmin and the average pressure P3flat. It is determined whether any one of the absolute values (| P3revmin−P3flat |) exceeds a predetermined allowable value D. If it is determined that one of the values exceeds the predetermined allowable value D (YES in step S104 in FIG. 3), the process proceeds to step S105 in FIG. Further, when it is determined that none of them exceeds the predetermined allowable value D (when NO is determined in step S104 in FIG. 3), the process returns to step S102 in FIG. 3 and the average pressure P3flat and the preliminary pressure during the discharge stroke. Monitoring of the maximum pressure P3revmax and the minimum pressure P3revmin during the compression stroke is continued.

  If YES is determined in step S104 of FIG. 3, the control unit 70 determines whether or not the maximum pressure P3revmax exceeds the average pressure P3flat in step S105 of FIG. If it is determined YES in step S105 of FIG. 3, the control unit 70 proceeds to step S106 of FIG. 3, and advances the rotation angle φ at which the rotation speed of the servo motor 11 during the next preliminary compression stroke starts to decrease by ΔX. To do. Note that when it is determined YES in step S105 of FIG. 3 for the first time immediately after the start of the non-pulsating pump 100, the control unit 70 sets the rotation angle at which the rotation speed of the servo motor 11 starts to be reduced to the rotation angle (0 ° − ΔX). This operation will be described in detail later with reference to FIGS.

  On the other hand, if NO is determined in step S105 of FIG. 3, the control unit 70 proceeds to step S107 of FIG. 3 and confirms that the minimum pressure P3revmin is lower than the average pressure P3flat. Then, the process proceeds to step S108 in FIG. 3, and the rotation angle φ for starting the reduction of the rotation speed of the servo motor 11 during the next preliminary compression stroke is delayed by ΔX. This operation will be described in detail later with reference to FIGS.

  When the operation of step S106 or step S108 in FIG. 3 is completed, the control unit 70 proceeds to step S109 in FIG. 3 and determines whether or not the pulsation pump 100 has stopped. If the pulsating pump 100 is not stopped, NO is determined in step S109 in FIG. 3, the process returns to step S102 in FIG. 3, and the operations from step S102 to step S108 are repeated. On the other hand, if the non-pulsating pump 100 is stopped, YES is determined in step S109, and the operation of the program is terminated.

Next, referring to FIGS. 4 to 7, the pressure P1 of the pump chamber 25, the pressure P2 of the pump chamber 45, the pressure P3 of the common discharge pipe 36, the speed of the plungers 26, 46, the servo motor 11 A change in the rotation speed will be described. In the following description, it is assumed that the average pressure P3flat (= set pressure P ^* ) during the discharge stroke is lower than the design pressure Pd.

4 (a) to 4 (b) show that immediately after the non-pulsating pump 100 is started, the rotational speed of the servo motor 11 is constantly rotated at a predetermined rotational speed R0 as indicated by a solid line 95c in FIG. 4 (c). Change of the pressure P1 of the pump chamber 25, the pressure P2 of the pump chamber 45, and the pressure P3 of the common discharge pipe 36 (solid line 92c, broken line 93c, and alternate long and short dash line 91c in FIG. The change of the speed (the solid line 82c of FIG.4 (b), the broken line 83c) is shown. Since the average pressure P3flat (= set pressure P ^* ) during the discharge stroke is lower than the design pressure Pd, when the rotational speed of the servo motor 11 is constant at a predetermined rotational speed R0, as shown in FIG. Further, when the rotation angle φ is φ11, the pressure P1 of the pump chamber 25 reaches the average pressure P3flat (= set pressure P ^* ) during the discharge stroke, and the pump chamber 25 enters the common discharge pipe 36 during the pre-compression stroke. Fluid will be discharged. When the rotation angle φ of the rotary cam 15 is −φ11, the plunger 46 of the second pump 40 moves in the discharge direction at a constant speed as shown by the broken line 83c in FIG. It discharges to the discharge pipe 36. For this reason, the flow rate of the fluid flowing through the common discharge pipe 36 becomes the total flow rate of the fluid flow rate discharged from the first pump 20 to a constant flow rate discharged from the second pump 40, and is indicated by a one-dot chain line 91c in FIG. As shown, the maximum pressure P3revmax of the common discharge pipe 36 during the pre-compression stroke exceeds the average pressure P3flat (= set pressure P ^* ) during the discharge stroke of the common discharge pipe 36, and pulsation occurs in the total discharge flow rate. 4A to 4C, the absolute value (| P3revmax−P3flat |) of the difference between the maximum pressure P3revmax and the average pressure P3flat exceeds a predetermined allowable value D.

  Therefore, the control unit 70 determines YES in steps S104 and S105 in FIG. 3 and proceeds to step S106 in FIG. At this time, since it is the first time that the control unit 70 determines YES in step S105 of FIG. 5, the rotation starts to reduce the rotation speed of the servo motor 11 during the next preliminary compression stroke in step S106 of FIG. The angle φ is set to a rotation angle φ21 that is (0 ° −ΔX). Then, as shown by a solid line 95d in FIG. 5C, the control unit 70 sets the rotation speed of the servo motor 11 to a predetermined rotation speed R0 at the rotation angle φ21 (0 ° −ΔX) during the next preliminary compression stroke. The rotational speed of the servo motor 11 is reduced so that the rotational speed of the servo motor 11 returns to the predetermined rotational speed R0 at a rotational angle of 0 °, which is decreased by ΔR1 and increased from the rotational angle φ20 to complete the preliminary compression stroke. Adjust. In this case, the range of the rotation angle φ in which the servo motor 11 is reduced below the predetermined rotation speed R0 is ΔX (°), and during this period, the rotation angle range ΔX (°) is the rotation angular velocity of the rotary cam 15. ΔT1 = (ΔX / ω) (sec) divided by ω (° / sec).

In this way, by reducing the rotation speed of the servo motor 11 from the predetermined rotation speed R0 between the rotation angle φ21 and the rotation angle 0 ° at which the preliminary compression stroke ends, a solid line 82d in FIG. As described above, the speed of the plunger 26 of the first pump 20 between the rotation angle φ21 and the rotation angle 0 ° decreases, and the flow rate discharged from the first pump 20 to the common discharge pipe 36 decreases during this time. Further, as indicated by a broken line 83d in FIG. 5B, the speed of the plunger 46 of the second pump 40 also decreases during this time, so the flow rate discharged from the second pump to the common discharge pipe 36 also decreases. Therefore, as shown in FIG. 5A, the pressure P1 of the pump chamber 25 and the pressure P3 of the common discharge pipe between the rotation angle φ21 and the rotation angle 0 ° are lower than in the case of FIG. However, as shown in FIG. 5A, the maximum pressure P3revmax of the common discharge pipe 36 between the rotation angles φ11 and φ21 hardly decreases, and the average pressure P3flat (during the discharge stroke of the common discharge pipe 36) = Set pressure P ^* ) is still exceeded. 5A to 5C, the absolute value (| P3revmax−P3flat |) of the difference between the maximum pressure P3revmax and the average pressure P3flat exceeds a predetermined allowable value D.

Since the non-pulsating pump 100 continues to operate, the control unit 70 sets the rotation angle φ (0 ° −ΔX) at which the rotation speed of the servo motor 11 during the next preliminary compression stroke starts to be reduced in step S106 of FIG. ) Is set to the rotation angle φ21, NO is determined in step S109 in FIG. 3, and the process returns to step S102 in FIG. In the same manner as described above, the pressure sensor 63 detects the average pressure P3flat of the common discharge pipe 36 during the discharge stroke during the discharge stroke, and the common discharge pipe is detected in step S103 of FIG. A maximum pressure P3revmax of 36 is detected. As described above, in the state of FIGS. 5A to 5C, the maximum pressure P3revmax of the common discharge pipe 36 during the preliminary compression stroke is equal to the average pressure P3flat (= The set pressure P ^* ) remains exceeded, and the absolute value (| P3revmax−P3flat |) of the difference between the maximum pressure P3revmax and the average pressure P3flat exceeds a predetermined allowable value D. For this reason, the control unit 70 determines YES in steps S104 and S105 of FIG. 3, and proceeds to step S106 of FIG.

  Since this time is the second time that YES is determined in step S105 in FIG. 3, the controller 70 rotates the rotation speed of the servo motor 11 during the next precompression stroke, as indicated by the solid line 95e in FIG. Is set to a rotation angle φ22 that is earlier than the current rotation angle φ21 by ΔX (φ22 = φ21−ΔX). Then, as shown by a solid line 95e in FIG. 6C, the control unit 70 changes the rotation speed of the servo motor 11 from the predetermined rotation speed R0 at the rotation angle φ22 (φ21−ΔX) during the next preliminary compression stroke. Decrease by ΔR2, increase the rotation speed from the rotation angle φ21, and adjust the rotation speed of the servo motor 11 so that the rotation speed of the servo motor 11 returns to the predetermined rotation speed R0 at the rotation angle of 0 ° when the preliminary compression stroke ends. adjust. In this case, the range of the rotation angle φ in which the servo motor 11 is reduced from the predetermined rotation speed R0 is 2 × ΔX (°), and during this period, the rotation angle range 2 × ΔX (°) is the rotational cam. ΔT2 = (2 × ΔX / ω) (sec) divided by 15 rotation angular velocity ω (° / sec).

  Here, the rotational speed reduction amount ΔR2 is the maximum amount that does not cause a loss of the discharge flow rate in the preliminary compression stroke after the rotational speed of the servo motor 11 is reduced.

In this way, by reducing the rotational speed of the servo motor 11 from the predetermined rotational speed R0 between the rotational angle φ22 and the rotational angle 0 ° at which the pre-compression stroke ends, a solid line 82e in FIG. As described above, the speed of the plunger 26 of the first pump 20 between the rotation angle φ22 and the rotation angle 0 ° decreases, and the flow rate discharged from the first pump 20 to the common discharge pipe 36 decreases during this time. Further, as indicated by a broken line 83e in FIG. 6B, the speed of the plunger 46 of the second pump 40 also decreases during this time, so the flow rate discharged from the second pump to the common discharge pipe 36 also decreases. Therefore, as shown in FIG. 6A, the pressure P1 of the pump chamber 25 and the pressure P3 of the common discharge pipe between the rotation angle φ22 and the rotation angle 0 ° are lower than in the case of FIG. . However, as shown in FIG. 6A, the maximum pressure P3revmax of the common discharge pipe 36 between the rotation angles φ11 and φ22 hardly decreases, and the average pressure P3flat (during the discharge stroke of the common discharge pipe 36) = Set pressure P ^* ) is still exceeded. In the state shown in FIGS. 6A to 6C, the absolute value (| P3revmax−P3flat |) of the difference between the maximum pressure P3revmax and the average pressure P3flat exceeds a predetermined allowable value D.

As described above, when the non-pulsating pump 100 continues to operate, the control unit 70 returns to step S102 in FIG. 3 and the pressure is stabilized during the discharge stroke by the pressure sensor 63. The average pressure P3flat of the common discharge pipe 36 during a certain period is detected, and the maximum pressure P3revmax of the common discharge pipe 36 is detected in step S103 of FIG. As described above, in the state shown in FIGS. 6A to 6C, the maximum pressure P3revmax of the common discharge pipe 36 during the preliminary compression stroke is equal to the average pressure P3flat (= The set pressure P ^* ) remains exceeded, and the absolute value (| P3revmax−P3flat |) of the difference between the maximum pressure P3revmax and the average pressure P3flat exceeds a predetermined allowable value D. For this reason, the control unit 70 determines YES in steps S104 and S105 of FIG. 3, and proceeds to step S106 of FIG.

  This time, since it is the third time to determine YES in step S105 of FIG. 3, as shown by the solid line 95f in FIG. 7C, the control unit 70 rotates the rotation speed of the servo motor 11 during the next preliminary compression stroke. Is set to a rotation angle φ11 (φ11 = φ22−ΔX) that is earlier than the current rotation angle φ22 by ΔX. As described above, the rotational speed of the servo motor 11 can be reduced only to ΔR2, which is the maximum amount that does not cause a loss of the discharge flow rate in the preliminary compression stroke after the rotational speed of the servo motor 11 is reduced. As shown by a solid line 95f in FIG. 7C, the rotation speed of the servo motor 11 is reduced from the predetermined rotation speed R0 to ΔR2 at the rotation angle φ11 (φ22−ΔX) during the next preliminary compression stroke. During the period from the angle φ21 to the rotation angle φ21, the amount of reduction in the rotation speed of the servomotor 11 is kept at ΔR2, and the rotation speed is increased from the rotation angle φ21 to reach the rotation angle 0 ° at which the preliminary compression process is completed. The rotational speed of the servo motor 11 is adjusted so that the rotational speed returns to the predetermined rotational speed R0. In this case, the range of the rotation angle φ in which the servo motor 11 is reduced below the predetermined rotation speed R0 is 3 × ΔX (°), and during this period, the rotation angle range 3 × ΔX (°) is within the rotational cam. ΔT3 = (3 × ΔX / ω) (sec) divided by 15 rotational angular velocities ω (° / sec).

  In this way, by reducing the rotation speed of the servo motor 11 from the predetermined rotation speed R0 between the rotation angle φ11 and the rotation angle 0 ° at which the preliminary compression stroke ends, a solid line 82f in FIG. As described above, the speed of the plunger 26 of the first pump 20 between the rotation angle φ11 and the rotation angle 0 ° decreases, and the flow rate discharged from the first pump 20 to the common discharge pipe 36 decreases during this time. Further, as indicated by a broken line 83f in FIG. 7B, the speed of the plunger 46 of the second pump 40 also decreases during this time, so that the flow rate discharged from the second pump to the common discharge pipe 36 also decreases.

Thereby, the amount of reduction in the discharge flow rate from the first pump 20 during the pre-compression stroke from the rotation angle φ11 to the rotation angle 0 ° and the second pump 40 from the rotation angle φ11 to the rotation angle 0 °. Since the total reduction flow rate with the reduction amount of the discharge flow rate and the excess discharge flow rate during the pre-compression stroke are offset, the flow rate discharged to the common discharge pipe 36 is stable during the discharge stroke described above. The discharge flow rate is the same as the discharge flow rate during a period when the discharge flow rate is stable (for example, when one of the first pump 20 or the second pump 40 is in the discharge stroke and the plunger speed is constant and the other is in the suction stroke). Flow rate is lost, and flow pulsation is eliminated. Further, since flow rate pulsation is eliminated, the pressure P1 of the pump chamber 25 and the pressure P3 of the common discharge pipe 36 during the pre-compression stroke are also shown in the common discharge pipe 36 as shown by the solid line 92f and the alternate long and short dash line 91f of FIG. The pressure is equal to the average pressure P3flat (= set pressure P ^* ) during the discharge stroke, and pressure pulsation is eliminated.

  Since the non-pulsating pump 100 is operating, the control unit 70 returns to step S102 in FIG. 3 and uses the pressure sensor 63 to set the average pressure P3flat of the common discharge pipe 36 during the period in which the pressure is stable during the discharge stroke. In step S103 of FIG. 3, the maximum pressure P3revmax of the common discharge pipe 36 is detected. As described with reference to FIGS. 7 (a) to 7 (c), in the state shown in FIGS. 7 (a) to 7 (c), the pulsation during the pre-compression stroke is suppressed, and the maximum pressure P3revmax and The absolute value of the difference between the average pressure P3flat (| P3revmax−P3flat |) and the absolute value of the difference between the minimum pressure P3revmin and the average pressure P3flat (| P3revmin−P3flat |) are both within the range of the predetermined allowable value D. ing. Therefore, the control unit 70 determines NO in step S104 in FIG. 3 and returns to step S102 in FIG. 3 without adjusting the rotation speed of the servo motor 11. In this case, the rotation speed of the servo motor 11 is maintained as indicated by a solid line 95f in FIG. 7C, and the speeds of the plungers 26 and 46 are maintained as indicated by a solid line 82f and a broken line 83f in FIG. 7B. .

Thereafter, as long as the set pressure P ^* does not fluctuate greatly, the states shown in FIGS. 7A to 7C are maintained.

  As described above, the non-pulsating pump 100 of the present embodiment performs pre-compression when the maximum pressure P3revmax of the common discharge pipe 36 during the pre-compression stroke is higher than the average pressure P3flat of the common discharge pipe 36 during the discharge stroke. During the stroke, the rotation speed of the servo motor 11 is reduced from the predetermined rotation speed R0, and the period from the rotation angle 0 ° where the preliminary compression stroke is completed is sequentially increased as the periods ΔT1 to ΔT3 for each preliminary compression stroke. As a result, the maximum pressure P3revmax of the common discharge pipe 36 during the pre-compression stroke is set to the same pressure as the average pressure P3flat of the common discharge pipe 36 during the discharge stroke, and pulsation of pressure and flow rate can be suppressed.

Next, when the average pressure P3flat (= set pressure P ^* ) during the discharge stroke of the common discharge pipe 36 increases from the case described with reference to FIGS. 7A to 7C to the design pressure Pd. The operation of the control unit 70 will be described with reference to FIG. 3, FIG. 8, and FIG.

As shown in FIG. 8 (a), when the average pressure P3flat (= set pressure P ^* ) during the discharge stroke of the common discharge pipe 36 rises, as previously described with reference to FIG. 2C, during the pre-compression stroke The excess discharge amount is zero. For this reason, as described with reference to FIGS. 7A to 7C, the rotation speed of the servo motor 11 is reduced from the rotation angle φ11 to the rotation angle 0 ° below the predetermined rotation speed R0. If so, the first pump 20 and the second pump 40 in the pre-compression stroke are reduced by the total reduction flow of the discharge flow reduction amount of the first pump 20 and the reduction amount of the second pump 40 in the pre-compression stroke. The total discharge flow rate becomes smaller than the flow rate during the period in which the pressure and flow rate are stable during the discharge stroke. Therefore, as indicated by the solid line 92g and the alternate long and short dash line 91g in FIG. 9, the pressure P1 of the pump chamber 25 and the pressure P3 of the common discharge pipe 36 are lower than the average pressure P3flat during the discharge stroke.

  The control unit 70 detects the average pressure P3flat of the common discharge pipe 36 during the period in which the pressure is stable during the discharge stroke by the pressure sensor 63 in step S102 of FIG. 3, and the common discharge pipe 36 in step S103 of FIG. The maximum pressure P3revmax and the minimum pressure P3revmin are detected. Then, the process proceeds to step S104 in FIG.

  As shown in FIG. 8A, as shown by the solid line 92g and the alternate long and short dash line 91g in FIG. 9, the pressure P1 in the pump chamber 25 and the pressure P3 in the common discharge pipe 36 are lower than the average pressure P3flat during the discharge stroke. The absolute value (| P3revmin−P3flat |) of the difference between the minimum pressure P3revmin and the average pressure P3flat exceeds a predetermined allowable value D. Therefore, the control unit 70 determines YES in step S104 in FIG. 3 and proceeds to step S105, determines NO in step S105 and proceeds to step S107 in FIG. 3 to confirm (P3revmin <P3flat). The process proceeds to step S108 in FIG.

  In step S108 of FIG. 3, the control unit 70 delays the rotation angle φ at which the rotation speed of the servo motor 11 during the next pre-compression stroke starts from the current rotation angle φ11 shown in FIG. 8C by ΔX. The rotation angle is φ22 (φ22 = φ11 + ΔX). Then, the control unit 70 returns from step S109 in FIG. 3 to step S102 in FIG. The control unit 70 continues until the absolute value (| P3revmin−P3flat |) of the difference between the minimum pressure P3revmin and the average pressure P3flat is equal to or less than the predetermined allowable value D and NO is determined in step S104 of FIG. Steps S102 to S105 and Steps S107 to S109 are repeatedly executed, and the rotation angle φ of the rotary cam 15 for starting the reduction of the rotation speed of the servo motor 11 at each preliminary compression stroke is delayed by ΔX, and the preliminary compression stroke is performed. During this, the period during which the rotation speed of the servo motor 11 is reduced from the predetermined rotation speed is sequentially shortened at each preliminary compression stroke. However, the control unit 70 does not make the rotation angle φ of the rotating cam 15 at which the rotation number of the servo motor 11 starts to be reduced slower than 0 °.

Then, as shown by a solid line 95h in FIG. 9C, the rotation angle φ of the rotary cam 15 that starts to reduce the rotation speed of the servo motor 11 becomes 0 °, and the solid line 82h and the broken line 83h in FIG. 9B. When the velocity curves of the plungers 26 and 46 shown in FIG. 2 are the same as the solid line 82 and the broken line 83 shown in FIG. 2A, the discharge flow rate from the first pump 20 during the pre-compression stroke from the rotation angle φ11 to the rotation angle 0 °. Since the reduction amount and the reduction amount of the discharge flow rate from the second pump 40 between the rotation angle φ11 and the rotation angle 0 ° are zero, the flow rate discharged to the common discharge pipe 36 is during the discharge stroke described above. The pressure is stable and the discharge flow rate is stable (for example, when one of the first pump 20 or the second pump 40 is in the discharge stroke and the plunger speed is constant, and the other is in the suction stroke) Same as the discharge flow rate Becomes the amount, the pulse of the flow rate is eliminated. Further, since the pulsation of the flow rate is eliminated, the pressure P1 of the pump chamber 25 and the pressure P3 of the common discharge pipe 36 during the pre-compression stroke are also shown in the common discharge pipe 36 as shown by a solid line 92h and a dashed line 91h in FIG. The pressure is equal to the average pressure P3flat (= set pressure P ^* ) during the discharge stroke, and pressure pulsation is eliminated.

  As described above, the non-pulsating pump 100 according to the present embodiment is configured such that when the maximum pressure P3revmin of the common discharge pipe 36 during the preliminary compression stroke is lower than the average pressure P3flat of the common discharge pipe 36 during the discharge stroke, During the compression stroke, the rotation speed of the servo motor 11 is reduced from the predetermined rotation speed R0, and the period from the rotation angle of 0 ° where the preliminary compression stroke ends is sequentially shortened for each preliminary compression stroke. Pressure and flow pulsation can be suppressed by setting the minimum pressure P3revmin of the common discharge pipe 36 during the compression stroke to the same pressure as the average pressure P3flat of the common discharge pipe 36 during the discharge stroke.

  As described above, the non-pulsating pump 100 according to the present embodiment is configured so that the maximum pressure P3revmax of the common discharge pipe 36 during the preliminary compression stroke is higher than the average pressure P3flat during the discharge stroke of the common discharge pipe 36. The period during which the rotational speed of the servo motor 11 is reduced from the predetermined rotational speed R0 during the preliminary compression stroke is sequentially increased every time the preliminary compression stroke is performed, and the maximum pressure P3revmin of the common discharge pipe 36 during the preliminary compression stroke is discharged. When the average pressure P3flat of the common discharge pipe 36 during the stroke becomes lower, the period during which the rotation speed of the servo motor 11 is reduced from the predetermined rotation speed R0 during the preliminary compression stroke is set for each preliminary compression stroke. By shortening sequentially, even if the average pressure P3flat during the discharge stroke of the common discharge pipe 36 fluctuates, the occurrence of pulsation can be suppressed by a simple method.

  It should be noted that increasing or shortening the period during which the rotation speed of the servo motor 11 is reduced from the predetermined rotation speed R0 during the pre-compression stroke is to reduce the rotation speed of the servo motor 11. For example, the servo motor 11 in the pre-compression stroke in which the rotation speed of the servo motor 11 is reduced from the predetermined rotation speed R0 during the pre-compression stroke is different. When a plurality of rotation speed change curves are prepared and the maximum pressure P3revmax of the common discharge pipe 36 during the pre-compression stroke becomes higher than the average pressure P3flat during the discharge stroke of the common discharge pipe 36, the pre-compression stroke Each time, the rotation speed of the servo motor 11 is sequentially switched to a change curve in which the period for reducing the rotation speed from the predetermined rotation speed R0 becomes longer, and the maximum pressure P3revmax of the common discharge pipe 36 during the pre-compression stroke is common. When the pressure becomes lower than the average pressure P3flat during the discharge stroke of the discharge pipe 36, the curve is switched to a change curve that shortens the period during which the rotation speed of the servo motor 11 is reduced from the predetermined rotation speed R0 in each preliminary compression stroke. You may do it.

10 frame, 11 servo motor, 12 shaft, 13 cam shaft, 15 rotating cam, 16 cam mechanism, 20, 40 pump, 22, 42 hydraulic chamber, 23, 43 diaphragm, 25, 45 pump chamber, 26, 46 plunger, 27 , 47 Packing, 28, 48 Plunger shaft, 29, 49 Roller, 30, 50 Suction pipe, 31, 33, 51, 53 Check valve, 32, 52 Discharge pipe, 35 Common suction pipe, 36 Common discharge pipe, 63 Pressure Sensor, 70 control unit, 71 CPU, 72 memory, 73 interface, 100 pulsation pump.

Claims (3)

A rotating cam that converts the rotational motion of a common motor into a plurality of reciprocating motions with a predetermined phase difference, and drives a plurality of reciprocating pumps with a predetermined phase difference via the rotating cam; Including a pre-compression stroke for stopping the plunger after moving the plunger of the reciprocating pump to the discharge side by a minute amount before the discharge stroke, and making the total discharge flow rate flowing out to the common discharge pipe constant A pump,
A pressure sensor for detecting the pressure of the discharge pipe;
A controller for adjusting the rotational speed of the motor,
When the pressure of the discharge pipe during the pre-compression stroke detected by the pressure sensor is higher than the pressure of the discharge pipe during the discharge stroke detected by the pressure sensor, the control unit performs the following pre-compression stroke By making the rotation angle of the rotation cam that starts the reduction of the rotation speed of the motor a predetermined angle earlier than the rotation angle of the rotation cam that starts the reduction of the rotation speed of the motor during the previous preliminary compression stroke, The rotational speed reduction period during which the rotational speed of the motor is reduced from a predetermined rotational speed during the pre-compression stroke is sequentially increased for each pre-compression stroke ,
The motor rotation speed is reduced by reducing the rotation speed at a predetermined change rate during the rotation speed reduction period and then increasing the rotation speed at the predetermined change ratio before starting the reduction at the end of the pre-compression stroke. The number of revolutions,
Non-pulsating pump characterized by The pulsating pump according to claim 1 ,
When the pressure of the discharge pipe during the previous pre-compression stroke detected by the pressure sensor is lower than the pressure of the discharge pipe during the discharge stroke detected by the pressure sensor, the control unit performs the next pre-compression stroke. The rotation angle of the rotating cam that starts the reduction of the rotation speed of the motor is delayed by the predetermined angle from the rotation angle of the rotation cam that starts the reduction of the rotation speed of the motor during the preliminary compression stroke. Accordingly, the rotation speed reduction period in which the rotation speed of the motor is reduced from a predetermined rotation speed during the preliminary compression stroke is sequentially shortened for each preliminary compression stroke,
Non-pulsating pump characterized by A pulsating pump according to claim 1 or 2,
The predetermined rate of change in the reduction in the rotational speed of the motor is the maximum reduction amount that does not cause a loss of the discharge flow rate in the preliminary compression stroke after the rotational speed is reduced while the rotational angle of the rotating cam is changed by a predetermined angle. Changing the rotational speed,
Non-pulsating pump characterized by

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