JP2013204619A - Hydraulic module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic module which has simple configuration, can stably keep a hydraulic fluid at a fixed viscosity and can stably retain the hydraulic fluid at a predetermined pressure.SOLUTION: A hydraulic module 1 includes: a pump 11 which feeds out a hydraulic fluid stored in a tank 10; a motor 12 which is connected to the pump 11 and drives it; and a control means 13 which controls rotation of a motor 12. The pump 11 is driven by rotating the motor 12 and supplies the hydraulic fluid to operate an actuator 2. When keeping an operating state of the actuator 2, the motor 12 is rotated at a lower speed in comparison with the rotation for operating the actuator, therefore controlling the hydraulic fluid to be retained at a predetermined pressure. The hydraulic module further includes at least a detection means 14 for detecting the pressure of the hydraulic fluid during the pressure retaining control, and a cooling means 15 for cooling the hydraulic fluid when the pressure detected by the detection means 14 is reduced.

Description

  The present invention relates to a hydraulic module, and in particular, when a pump is driven by rotation of a motor to supply hydraulic oil to operate an actuator, the motor is operated at a lower speed than the rotation when the operating state of the actuator is maintained. The present invention relates to a hydraulic module that can be controlled to rotate and maintain the pressure of hydraulic oil.

  A hydraulic module that operates an actuator generally includes a pump that feeds hydraulic oil stored in a tank, a motor that is connected to and drives the pump, and a control unit that controls rotation of the motor. As an actuator operated by the hydraulic module, for example, there is a hydraulic cylinder connected to a jig for clamping a workpiece. In such a hydraulic cylinder, at the time of operation for clamping and / or unclamping the workpiece, the motor is rotated at a predetermined speed to drive the pump and to supply the hydraulic oil. Further, when holding the workpiece clamped state, the pressure of the hydraulic oil acting on the hydraulic cylinder is held (at the time of holding the pressure).

  Here, as described above, when the hydraulic oil pressure is maintained, the motor is generally kept rotating. At this time, in order to reduce the energy used, it is generally performed to reduce the hydraulic oil supply flow rate by controlling the motor rotation speed to be lower than that during operation of the actuator. .

  Patent Document 1 is known as a conventional technique related to the control of such hydraulic oil. Patent Document 1 discloses that the hydraulic oil is depressurized by using a control mode in which the large-diameter chamber of the decompression cylinder is communicated with the pressurization chamber of the hydraulic cylinder, and the clamping force is controlled with a hydraulic pressure lower than the pump pressure. ing.

JP 2003-166501 A

  However, the viscosity of hydraulic oil tends to decrease when the temperature rises due to flow resistance when it is fed. When the viscosity of hydraulic oil decreases, the amount of leakage that occurs in gaps in the pump and the like increases, and as a result, the flow resistance increases particularly during pressure holding, and the temperature rises further. Due to the vicious cycle in which the increase in temperature and the temperature rise are repeated, it is not possible to secure the necessary flow rate of hydraulic oil to the actuator when the pressure is maintained. On the other hand, the motor is controlled by the control means to a preset number of revolutions that is required for sending hydraulic oil having a predetermined viscosity at a predetermined flow rate. Therefore, there has been a problem that the pressure acting on the actuator of the hydraulic oil cannot be maintained at a set value. And such a problem will generate | occur | produce not only in a pump but between a pressure reduction cylinder and a piston in patent document 1 similarly.

  The present invention has been made in view of the above-described problems. A hydraulic module capable of stably maintaining hydraulic oil at a constant viscosity and stably holding hydraulic oil at a predetermined pressure with a simple configuration. The purpose is to provide.

  In order to achieve the above object, according to the first aspect of the present invention, the pump is driven by the rotation of the motor to supply hydraulic oil to operate the actuator, and the motor is rotated when the operating state of the actuator is maintained. Is a hydraulic module that can be controlled to rotate at a low speed and maintain the pressure of hydraulic oil as compared to the detection means, detecting at least the pressure of hydraulic oil during pressure holding control, and detecting by the detection means And cooling means for cooling the hydraulic oil when the applied pressure is reduced.

  According to the first aspect of the present invention, at least the detection means for detecting the pressure of the hydraulic oil during the pressure holding control and the cooling means for cooling the hydraulic oil when the pressure detected by the detection means decreases are provided. The pump is driven to discharge a relatively small amount of hydraulic oil by detecting the pressure of the hydraulic oil when it is controlled to maintain at least a predetermined pressure by the detection means. Nevertheless, when the hydraulic oil pressure drops due to a rise in the temperature of the hydraulic oil and a decrease in its viscosity, the hydraulic oil is cooled by the cooling means and recovered to increase its viscosity. Since oil can be stably maintained at a constant viscosity, a hydraulic module capable of stably maintaining hydraulic oil at a predetermined pressure can be provided.

1 is a system diagram conceptually shown to explain an embodiment of a hydraulic module of the present invention. According to the present invention, when the pressure of the hydraulic oil detected at the time of holding the pressure decreases, the operation with respect to the time is shown to explain that the pressure is recovered by operating the cooling means to cool the hydraulic oil. It is the graph which showed the pressure change of oil.

An embodiment of a hydraulic module 1 according to the present invention will be described in detail with reference to FIG. In the drawings, the same reference numerals denote the same or corresponding parts.
The hydraulic module 1 according to the present invention generally includes a pump 11 that feeds hydraulic oil stored in a tank 10, a motor 12 that is connected to and drives the pump 11, and a control unit 13 that controls the rotation of the motor 12. The pump 11 is driven by the rotation of the motor 12 and hydraulic oil is supplied to operate the actuator 2. When the operating state of the actuator 2 is maintained, the motor 12 rotates at a lower speed than the rotation at the time of operation. The hydraulic oil can be controlled to be held at a predetermined pressure, and at least the detection means 14 for detecting the pressure of the hydraulic oil during the pressure holding control, and the pressure detected by the detection means 14 Cooling means 15 is further provided for cooling the hydraulic oil when it is lowered.

  The pump 11 is provided in the middle of a pipeline 16 for supplying hydraulic oil from the tank 10 to the actuator 2 such as a hydraulic cylinder. Between the actuator 2 and the tank 10, a pipe line 17 for returning the hydraulic oil from the actuator 2 to the tank 10 is also provided. In addition, the pipes 16 and 17 can be provided with an on-off valve, a switching valve, a relief valve, or the like as necessary.

  An electric motor 12 is connected to the pump 11, and an inverter 20 for adjusting the rotation speed is connected to the electric motor 12. A programmable logic control device (hereinafter referred to as PLC) 22 having input / output means such as a touch panel 21 is connected to the inverter 20, and a control signal is sent to the inverter 20 according to the set amount and pressure of hydraulic oil. It is comprised so that it can output and the rotational speed of the motor 12 can be adjusted.

  Between the pump 11 and the actuator 2 in the pipe line 16, a pressure sensor 14 is provided as a detection means for detecting the pressure of the hydraulic oil supplied to the actuator 2 by the pump 11. The pressure sensor 14 is connected to the PLC 22, and is configured to output the hydraulic oil pressure signal detected by the pressure sensor 14 to the PLC 22. The PLC 22 and the inverter 20 constitute a control means 13 for controlling the rotation of the motor 12.

  In the case of this embodiment, the cooling means 15 includes a cooler 23 connected to the pump 11 and a blower 24 for sending air to the cooler 23, and a motor 26 that drives a fan 25 of the blower 24. Is configured to be intermittently operated (ON / OFF control) by a signal output from the PLC 22. In addition, the motor 26 that drives the fan 25 of the blower 24 can be configured not only to turn on / off, but also to be able to adjust the rotation speed according to the temperature rise of the hydraulic oil.

  Next, the operation of the hydraulic module 1 configured as described above will be described in detail based on FIG. 2 in the case of the hydraulic cylinder 2 connected to a jig for clamping a workpiece as an actuator. In the hydraulic module 1 of the present invention, generally, when the hydraulic oil is held at a predetermined pressure, the pump 11 controls the drive of the motor 12 so that a relatively small amount of hydraulic oil is discharged. The pressure of the hydraulic oil when it is controlled so as to be held at is detected, and the hydraulic oil is cooled when the detected pressure of the hydraulic oil decreases.

  When the actuator 2 to which the hydraulic oil is fed by the hydraulic module 1 is the hydraulic cylinder 2 connected to the jig for clamping the workpiece as described above, the touch panel is used during the operation for clamping or unclamping the workpiece. The PLC 22 outputs a control signal to the inverter 20 to drive the pump 11 so as to rotate the motor 12 at a predetermined speed in accordance with the set value at the time of clamping / unclamping input at 21 to drive a predetermined amount, a predetermined pressure. Then, hydraulic oil is supplied to the actuator 2.

  On the other hand, when holding the workpiece in the clamped state, the PLC 22 outputs a control signal to the inverter 20 so that the PLC 22 rotates the motor 12 at a predetermined speed in accordance with the set value at the time of pressure holding control input on the touch panel 21. The pump 11 is driven. At this time, the rotation speed of the motor 12 whose rotation is controlled by the PLC 22 is set lower than that during the above-described workpiece clamping / unclamping operation, and is input to the PLC 22 via the touch panel 21. For this reason, the amount of hydraulic oil fed from the pump 11 to the hydraulic cylinder 2 is also smaller than that during the workpiece clamping / unclamping operation. The PLC 22 includes a set pressure value at the time of pressure holding control, a guaranteed pressure value at which the hydraulic cylinder 2 can hold the workpiece clamped state, and a cooling unit operation reference pressure that serves as a reference for operating the cooling unit 15. The value is input via the touch panel 21.

  At least when holding the clamped workpiece, the pressure detection sensor 14 detects the pressure of the hydraulic oil, and the detected hydraulic oil pressure signal is output to the PLC 22. At this time, when the temperature of the hydraulic oil increases due to flow resistance or the like, the viscosity decreases and the pressure leaks due to leakage in the pump 11.

  Therefore, in the present invention, the PLC 22 determines whether or not the detected actual pressure is lower than the cooling means operation reference pressure and whether or not the pressure has recovered to the set pressure value. As shown in FIG. 2, when the pressure of the hydraulic oil does not fall below the cooling unit operation reference pressure, the PLC 22 does not rotationally drive the motor 26 connected to the fan 25 of the blower 24 (OFF). On the other hand, when the pressure of the hydraulic oil is lower than the cooling unit operation reference pressure, the PLC 22 rotates the motor 26 connected to the fan 25 of the blower 24 (ON) and blows air to the cooler 23 to cool the hydraulic oil. To do. Thereby, the temperature of the hydraulic oil decreases, the viscosity returns, and the pressure increases. When the PLC 22 determines that the hydraulic oil pressure has recovered to the set pressure value during the pressure holding control, the PLC 22 stops the rotation drive of the motor 26 connected to the fan 25 of the blower 24 (OFF).

  As described above, in the present invention, in order to prevent the viscosity from being lowered due to the increase in the temperature of the hydraulic oil and consequently the pressure from being lowered, the pressure of the hydraulic oil is surely changed from the guaranteed pressure value to the set pressure value. It can be stably held during. In addition, the pressure detection sensor 14 is not limited to what detects the pressure of the hydraulic fluid at the time of pressure holding, and may always detect.

  1: hydraulic module, 2: hydraulic cylinder (actuator), 10: tank, 11: pump, 12: motor, 13: control means, 14: pressure sensor (detection means), 15: cooling means,

Claims (1)

The pump is driven by the rotation of the motor to supply hydraulic oil to operate the actuator, and when the operating state of the actuator is maintained, the motor is rotated at a lower speed than the rotation to maintain the hydraulic oil pressure. A hydraulic module that can be controlled as follows:
Detection means for detecting at least the pressure of hydraulic oil during pressure holding control;
A hydraulic module comprising: cooling means for cooling the hydraulic oil when the pressure detected by the detection means decreases.

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