JPH02223688A - Fluid pressurizing pump - Google Patents

Abstract

PURPOSE:To increase efficiency and to improve durability of a pump by providing a pressure detector to detect the delivery pressure of a hydraulic pump and an inverter circuit to vary the drive frequency of a motor by means of a frequency conversion signal. CONSTITUTION:An induction motor 52 drives a hydraulic pump 50. A pressure sensor 58 detects the delivery pressure of the hydraulic pump 50. A comparator 60 outputs a frequency conversion signal (c) based on a difference D between a set pressure PS of a setter 62 and a delivery pressure PL. An inverter circuit 64 to change the drive frequency of a motor 52 by means of a frequency conversion signal (c) is provided, and a motor speed is controlled so that a delivery pressure is adjusted to a set value. This constitution enables the increases of efficiency and improvement of durability of a pump.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fluid pressurizing pump device that pressurizes cleaning liquid or the like to a predetermined high pressure.

(Background of the Invention) There is a known device that sprays a high-pressure cleaning liquid from a nozzle and applies the high-pressure jet stream to the workpiece to clean the workpiece or remove debris generated during injection molding of the workpiece. In this case, a pump device is required to pressurize the cleaning liquid to a predetermined high pressure, but this pump device can maintain a constant pressure even if the jet ejection amount changes, such as by changing the number of nozzles or nozzle diameter. It is necessary that there be.

FIG. 2 is a circuit diagram of such a conventional device. In this figure, reference numeral 1 indicates a plunger type hydraulic pump, 2 a motor for driving the pump 1, 3 a cleaning liquid tank, and 4 a pressure regulating valve. Pump 1 is rotated at a constant speed by motor 2,
A hydraulic pressure sufficiently higher than the set pressure is generated, and this pump discharge pressure is kept constant by a pressure control valve 4. That is, the pressure control valve 4 opens when the pump discharge pressure exceeds the set pressure and returns a portion of the pump discharge liquid to the cleaning liquid tank 3 to maintain the supply pressure to the transmission line 5 at the set pressure. This transmission line 5 is provided with a nozzle 6 from which a jet stream of a predetermined pressure is ejected.

However, according to this conventional device, the pump 1 must always discharge the nozzle injection amount Q, a larger amount Q, and the difference (Q, -Q,) is always transferred from the pressure control valve 4 to the cleaning liquid tank 3. There was a problem that it was inefficient because it had to be returned.

Furthermore, since the pump 1 is driven at a constant rated rotational speed N, the pV value, which is the product of the motion speed V of a sliding part such as a piston inside the pump and the pressure p applied thereto, is always high. This causes the disadvantage that the sliding portion of the pump 1 is accelerated in wear.

Furthermore, since the pressure control valve 4 continues to open and close at all times, its valve seat tends to wear out, and especially when regulating the pressure of water, which has poor lubricity, at a constant level, it becomes more durable due to heat generation and galling near the seating part. The problem was that it got worse.

(Objective of the Invention) The present invention has been made in view of the above circumstances, and provides a pump with high efficiency and improved durability, and also eliminates the need for a pressure control valve and eliminates the need to take into account problems with the pressure control valve. The purpose of the present invention is to provide a fluid pressurization pump device that has been removed.

(Structure of the Invention) According to the present invention, this object is to provide a fluid pressurizing pump device that manages and outputs a fluid at a constant pressure, which includes a hydraulic pump, an induction motor that drives the hydraulic pump, and an induction motor that drives the hydraulic pump. a pressure detector that detects the discharge pressure of the hydraulic pump; a set pressure setter; a comparator that outputs a frequency conversion signal based on the difference between the discharge pressure of the hydraulic pump and the set pressure; and the frequency conversion. This is achieved by a fluid pressurizing pump device characterized in that it includes an inverter circuit that changes the drive frequency of the motor in response to a signal, and controls the motor speed so that the discharge pressure is a set pressure.

(Embodiment) FIG. 1 is a conceptual diagram of an embodiment of the present invention.・- example uses high-pressure cleaning liquid pressurized by a pump device to
This is used to clean and deburr workpieces such as C-frames. A workpiece (not shown) is placed on a horizontal conveyor 10 and sent in the X direction at a constant speed.
A scanning substrate 12 is held above by a frame (not shown) so as to be movable on a horizontal plane. This scanning substrate is rotated and scanned within this horizontal plane by an eccentric cam 14 (14a, 14b). That is, each eccentric cam 14 has a circular disk 16 (16a, b) that rotates synchronously, and a disk 16 that rotates synchronously.
The bin 18 (18a
, b) and the lower end of the bottle 18 is fixed to the scanning substrate 12. 22 (22a-d) are nozzles;
They are attached to the side edges of the scanning board 12 at appropriate intervals. A constant pressure high-pressure cleaning liquid is supplied to this nozzle 22 from a liquid pressurizing pump device according to the present invention, which will be described later.

Therefore, the jet stream ejected from each nozzle 22 follows a spiral trajectory 24 (24a-d) on the conveyor 10.
While drawing, touch the work and clean and remove any dirt from the work.

Next, the fluid pressure pump device of the present invention will be explained.

50 is, for example, a plunger type pressure pump, 52 is an induction motor that drives this pump 50, and 54 is a cleaning liquid tank. Fluid delivered by pump 50 is distributed to each nozzle 22 by high pressure transmission line 56 . 58 is a pressure sensor, which transmits the fluid pressure (pump discharge pressure) in 56;
PL is detected and converted into an electrical signal a. The pressure sensor 58 may be one that electrically detects the displacement of a diaphragm using a strain gauge or a piezoelectric element, or one that detects movable parts such as a diaphragm or cantilever and a piezo element on a semiconductor substrate using a method similar to the IC manufacturing method. A semiconductor pressure sensor or the like can be used in which the movable part is integrally formed with the movable part and the displacement of the movable part is detected by the detection part.

The output electrical signal a of this pressure sensor 58 is input to a comparator 60 consisting of an operational amplifier or the like. This comparator 60 receives an electric signal indicating the set pressure pH set by the setter 62, and the difference from the set pressure Ps is D=(PIT - P
L) is determined, and a frequency-converted signal C is output based on this difference.

An inverter circuit 64 changes the frequency f of the drive voltage supplied to the induction motor 52 based on this frequency conversion signal C. That is, when the nozzle 22 opens or the discharge amount increases and the discharge pressure PL becomes smaller than the set pressure P, the drive frequency f is increased according to the difference, and the motor 52
Increase the rotational speed N of. Conversely, when the nozzle 22 closes or the discharge amount decreases and the discharge pressure PL becomes higher than the set pressure P3, the drive frequency is lowered and the rotational speed N of the motor 52 is lowered. As a result, the discharge amount Q of the pump 50.

=qN follows the jetting amount Q discharged from the transmission line 56, and the discharge pressure PL of the transmission line 56 is kept constant. Note that q here is the discharge amount per rotation of the pump 50.

Although this embodiment has been described as being applied to a cleaning/deburring device and discharging cleaning liquid, the present invention can also be applied to, and includes, pressurized pumps for other fluids such as water and hydraulic pressure.

(Effects of the Invention) As described above, the present invention electrically detects the discharge pressure of a hydraulic pump using a pressure sensor, and changes the drive frequency of the injection motor based on the difference between the discharge pressure and the set pressure. Since the rotational speed of this motor is changed to set the discharge pressure to the set pressure, the pump only needs to supply the flow rate injected from the transmission line, and the entire pump and discharge amount do the work. This improves efficiency. In addition, since the pump only needs to discharge at the pressure of the transmission line, the pV value does not become excessive, and the service life of the seals and gaskets of the pump can be extended, improving their durability. Furthermore, since a pressure control valve that is mechanically opened and closed is not used, there is no need to consider troubles with the pressure control valve, and the reliability of the device is improved.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional device. 50... Hydraulic pump, 52... Induction motor, 58... Pressure sensor, 60... Comparator, 62... Setting device, 64... Inverter.

Claims (1)

[Claims] A fluid pressurizing pump device that outputs fluid by controlling it to a constant pressure, comprising: a hydraulic pump, an induction motor that drives the hydraulic pump, and a discharge pressure of the hydraulic pump. a pressure detector, a set pressure setting device, a comparator that outputs a frequency conversion signal based on the difference between the discharge pressure of the hydraulic pump and the set pressure, and changing the driving frequency of the motor based on the frequency conversion signal. An inverter circuit, and controlling a motor speed so that the discharge pressure is a set pressure.