JP2009079661A - Hydraulic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic device with small energy consumption when a single acting cylinder executes return operation. <P>SOLUTION: A first pilot check valve 15 is connected to a first load line 14, a second pilot check valve 18 is connected to a second load line 17, and a pilot line 21 of the first pilot check valve 15 is connected between the second pilot check valve 18 and the tip of the second load line 17. When the single acting cylinder 11 is subjected to return operation, a controller 32 communicates a pump port P of a magnetic directional control valve 13 with a second load port B, communicates a tank port T with a first load port A, instantaneously actuates a hydraulic pump 12, and then continues to deactivate the hydraulic pump 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydraulic apparatus such as a hydraulic apparatus or a hydraulic apparatus having a single acting cylinder.

  Conventionally, this type of hydraulic device is shown in FIG. 7 (Japanese Patent Laid-Open No. 9-296802: Patent Document 1). As shown in FIG. 7, this hydraulic apparatus includes a cylinder 1 that can function as a single-acting cylinder that drives a heavy load mold W, a hydraulic pump 2, and the hydraulic pump 2 and cylinder 1. And an electromagnetic proportional directional switching valve 3 connected to each other. A pilot check valve 5 is connected between the first load port A of the electromagnetic proportional direction switching valve 3 and the head side port 1 a of the cylinder 1, and the pilot pressure of the pilot check valve 5 is controlled by the electromagnetic switching valve 6. I have to.

When the mold W is dropped by its own weight, the electromagnetic proportional direction switching valve 3 is excited and held in the state switched to the position P1 (in this state P1, the cylinder 1 is a single acting cylinder). The hydraulic pump 2 is driven, and the electromagnetic switching valve 6 is excited to be positioned at the position S1 to apply pilot pressure to the pilot check valve 5, thereby opening the pilot check valve 5. Then, the liquid discharged from the head side port 1a of the single acting cylinder 1 due to the gravity of the mold W passes through the pilot check valve 5, the electromagnetic proportional direction switching valve 3 and the check valve 7, and the rod of the single acting cylinder 1 Supplied to the side port 1b, the mold W descends.
Japanese Patent Laid-Open No. 9-296802

  However, in the above-described conventional hydraulic device, the return operation of the pump 2 is completed in order to obtain the pilot pressure that keeps the pilot check valve 3 open while the return operation is performed by the dead weight of the die W of the single acting cylinder 1. And the electromagnetic proportional direction switching valve 3 and the electromagnetic switching valve 4 must be excited and held at the positions P1 and S1.

  As described above, in the conventional hydraulic apparatus, the pump 2 is continuously driven while the single-action cylinder 1 performs the return operation, and the direction switching valve 3 and the electromagnetic switching valve 4 are positioned at the positions P1 and S1. There was a problem that energy consumption was large because it was necessary to continue excitation in order to achieve this.

  Therefore, an object of the present invention is to provide a hydraulic device that consumes less energy when a single-acting cylinder performs a return operation.

In order to solve the above problems, the hydraulic device of the present invention is:
A single acting cylinder,
A direction switching valve;
A first pilot check connected to a first load line connecting the first load port of the direction switching valve and the single acting cylinder so that the flow from the first load port to the single acting cylinder is in the forward direction. A valve,
Connected to the second load line connected to the second load port of the direction switching valve and blocked at the tip thereof so that the flow from the second load port to the tip of the second load line is in the forward direction. A second pilot check valve;
A pump connected to the pump port of the direction switching valve;
A tank connected to the tank port of the direction switching valve,
The pilot line of the first pilot check valve is connected between the second pilot check valve and the tip of the second load line, while the pilot line of the second pilot check valve is connected to the first load line. It is characterized by that.

  According to the above configuration, when the single-acting cylinder is returned, the pump port of the direction switching valve and the second load port are connected, the tank port and the first load port are connected, and the pump is instantaneously connected. And the pressure of the liquid between the second pilot check valve and the tip of the second load line is set to a pressure that can open the first pilot check valve, and then the pump is stopped. . Then, even if the pump is stopped, the pressure of the liquid confined between the second pilot check valve and the tip of the second load line is transmitted to the first pilot check valve via the pilot line. Thus, since the first pilot check valve continues to open, the single-acting cylinder continues to return.

  Thus, when the single-acting cylinder performs a return operation, the first pilot check valve continues to open even if the pump is stopped and then the pump is stopped. Will continue to return.

  On the other hand, when the single-acting cylinder is moved forward, the pump port of the direction switching valve and the first load port are communicated, the tank port and the second load port are communicated, and the pump is driven.

  Then, the pressurized liquid from the pump is supplied to the single-acting cylinder via the pump port of the direction switching valve, the first load port, the first pilot check valve, and the first load line. The moving cylinder is moved forward.

  At this time, since the pilot line of the second pilot check valve is connected to the first load line, the second pilot check valve is opened by the high pilot pressure from the first load line. Therefore, the high-pressure liquid confined between the second pilot check valve and the tip of the second load line during the return operation is transferred to the tank via the second load port and the tank port of the direction switching valve. To be discharged.

  Next, when the drive of the pump is stopped and the forward movement of the single-action cylinder is stopped, the high-pressure liquid confined between the second pilot check valve and the tip of the second load line is already in the tank. Therefore, high pilot pressure does not act on the first pilot check valve, the first pilot check valve is closed to prevent backflow, and the single-acting cylinder is held in a stopped state. To do.

  Thus, during the forward movement of the single acting cylinder, the pressure of the first load line acts on the second pilot check valve as a high pilot pressure via the pilot line, and the second pilot check valve is opened. Since the high-pressure liquid confined between the second pilot check valve and the tip of the second load line has already been discharged to the tank, the pump is stopped and the single-acting cylinder is moved forward. When stopped, the first pilot check valve does not receive a high pilot pressure, so that the first pilot check valve can be reliably closed to prevent backflow and the single-acting cylinder can be reliably held in a stopped state.

  In this way, this hydraulic device can achieve energy saving because it does not drive the pump during the majority of the return motion of the single acting cylinder.

The hydraulic device of one embodiment is
When returning the single-acting cylinder, control is performed so that the pump port of the direction switching valve and the second load port communicate with each other, and the pump is instantaneously driven by the driving device, and then the driving device is stopped. And a control device for stopping the driving of the pump and returning to the single-acting cylinder in a state where the tank port and the first load port are in communication with each other.

  According to the embodiment, when the single-acting cylinder is returned, the control device controls the pump port of the direction switching valve and the second load port to communicate with each other and instantaneously drives the pump. It drives with an apparatus, and it controls so that the said drive device may be stopped after that.

  Therefore, according to the above-described embodiment, energy saving can be achieved because the pump is not driven during most of the return operation of the single acting cylinder.

In one embodiment,
The direction switching valve is an electromagnetic direction switching valve having an excited state and a demagnetized state,
The control device controls the electromagnetic directional control valve to a demagnetized state when returning to the single acting cylinder in a state where the driving of the pump is stopped.

  According to the embodiment, the control device controls the electromagnetic directional switching valve to the demagnetized state when the pump is stopped and the single-action cylinder returns to the single-acting cylinder. Energy can be saved as much as the direction switching valve is not energized.

The hydraulic device of one embodiment is
A first pressure sensor for detecting the pressure of the second load line between the second pilot check valve and the tip of the second load line;
The control device causes the driving device to drive the pump until the first pressure sensor detects a pressure equal to or higher than a pressure at which the first pilot check valve is opened when returning the single-acting cylinder.

  According to the embodiment, the pressure of the second load line between the second pilot check valve and the tip of the second load line is detected by the first pressure sensor, and the control device returns the single acting cylinder. When the pump is operated, the drive device drives the pump until the first pressure sensor detects a pressure equal to or higher than a pressure at which the first pilot check valve is opened. Therefore, the second pilot check valve and the second load line are driven. The pressure of the second load line between the first tip and the tip of the first pilot check valve can be reliably set to a pressure higher than the pressure at which the first pilot check valve is opened.

In one embodiment,
A second pressure sensor for detecting a pressure between the pump and the pump port of the direction switching valve;
The control device causes the drive device to drive the pump until the second pressure sensor detects a pressure equal to or higher than a pressure at which the first pilot check valve is opened when returning the single-acting cylinder.

  According to the above embodiment, the pressure between the pump and the pump port of the direction switching valve is detected by the second pressure sensor, and the control device performs the second operation when returning the single acting cylinder. The pump is driven by the driving device until the pressure sensor detects a pressure equal to or higher than the pressure at which the first pilot check valve is opened, so that the second between the second pilot check valve and the tip of the second load line. The pressure in the load line can be set to a pressure higher than the pressure at which the first pilot check valve is opened.

The hydraulic device of one embodiment is
A second pressure sensor for detecting a pressure between the pump and the pump port of the direction switching valve;
When the single-action cylinder returns, the control device causes the drive device to pump the pump until the first pressure sensor and the second pressure sensor detect a pressure equal to or higher than a pressure at which the first pilot check valve is opened. Drive.

  According to the embodiment, since the increase in pressure can be confirmed by both the first pressure sensor and the second pressure sensor, the second load line between the second pilot check valve and the tip of the second load line. Can be more reliably set to a pressure higher than the pressure at which the first pilot check valve is opened.

The hydraulic device of one embodiment is
With a timer,
The control device causes the drive device to drive the pump until the timer counts a predetermined time when the single-action cylinder is returned.

  According to the embodiment, the control device causes the driving device to drive the pump until the timer counts a predetermined time when returning the single-acting cylinder, and therefore the second pilot. The pressure of the 2nd load line between a check valve and the tip of the 2nd load line can be made into the pressure which can open the 1st pilot check valve more certainly.

  The time measurement start time of the timer can be, for example, the start time of driving the pump or the start time of the pressure increase detected by the first or second pressure sensor.

  According to the present invention, it is possible to reduce energy consumption when the single-action cylinder returns.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

(First embodiment)
As shown in FIG. 1, a hydraulic apparatus as an example of the hydraulic apparatus includes a single-action cylinder 11, a fixed displacement hydraulic pump 12 as an example of a hydraulic pump, and the hydraulic pump 12 and the single-action cylinder 11. And an electromagnetic direction switching valve 13 as an example of the direction switching valve connected between the two.

  The single acting cylinder 11 is a spring return type single acting cylinder in which the piston rod 11b is immersed by the spring force of the spring 11a and returns. The electromagnetic direction switching valve 13 is a three-position type electromagnetic direction switching valve, and is an ABT connection type in which the first load port A, the second load port B, and the tank port T communicate with each other at the normal position S0 in the demagnetized state.

  The first load port A of the electromagnetic directional switching valve 13 and the head side port 11c of the single acting cylinder 11 are connected by a first load line 14, and the single acting cylinder 11 is connected to the first load line 14 from the first load port A. The first pilot check valve 15 is connected so that the flow to the front is in the forward direction.

  Further, the second load line 17 is connected to the second load port B of the electromagnetic direction switching valve 13, and the tip 17a of the second load line 17 is blocked (closed). A second pilot check valve 18 is connected in the middle of the second load line 17 so that the flow from the second load port B to the tip of the second load line 17 is forward.

  The pilot line 21 of the first pilot check valve 15 is connected to the second load line 17 between the second pilot check valve 18 and the tip 17a. The pilot line 22 of the second pilot check valve 18 is connected to the first load line 14 between the first pilot check valve 15 and the first load port A of the electromagnetic direction switching valve 13.

  On the other hand, the hydraulic pump 12 is driven by a motor 31 as an example of a driving device. However, the drive device may be an engine.

  The motor 31 and the electromagnetic direction switching valve 13 are controlled by a control device 32. When the control device 32 projects the piston rod 11b of the single-acting cylinder 11, it outputs a signal for exciting the solenoid 13a of the electromagnetic direction switching valve 13 to position the electromagnetic direction switching valve 13 at the position S2. The pump port P and the first load port A are communicated, the tank port T and the second load port B are communicated, and a signal for driving the motor 31 is output.

  On the other hand, when the control device 32 causes the single-acting cylinder 11 to return with the spring force of the spring 11a, it instantaneously outputs a signal for exciting the solenoid 13b of the electromagnetic direction switching valve 13 to position the electromagnetic direction switching valve 13 in position. Located at S1, the pump port P and the second load port B are communicated, the tank port T and the first load port A are communicated, and the motor 31 is driven to drive the hydraulic pump 12, and then the motor 31 and a signal for demagnetizing the solenoids 13a and 13b of the electromagnetic direction switching valve 13, and the electromagnetic direction switching valve 13 is positioned at the normal position S0. The load ports A and B are communicated with the tank port T.

  More specifically, the control device 32 includes a timer 35, and when the single-acting cylinder 11 is returned and operated, the controller 35 measures a predetermined time (instantaneous) after the timer 35 starts driving the hydraulic pump 12. Until the motor 31 is driven, the solenoid 13b is excited so that the electromagnetic direction switching valve 13 is positioned at the position S1, and after the predetermined time is counted, the driving of the hydraulic pump 12 is stopped. Further, the solenoids 13a and 13b are demagnetized, and the electromagnetic direction switching valve 13 is controlled to be positioned at the normal position S0.

  The predetermined time measured by the timer 35 means that the pressure of the hydraulic oil in the second load line 17 between the second pilot check valve 18 and the tip 17a of the second load line 17 opens the first pilot check valve 15. The time until the pressure rises, or a slightly longer time in consideration of the margin.

  According to the hydraulic device having the above-described configuration, when the single-acting cylinder 11 is returned, the control device 32 continues until the timer 31 counts a predetermined time after the timer 35 starts driving the hydraulic pump 12. To drive the hydraulic pump 12 and to excite the solenoid 13b so as to position the electromagnetic direction switching valve 13 at the position S1 so that the pump port P communicates with the second load port B, and the time is measured. The drive of the motor 31 is stopped, the drive of the hydraulic pump 12 is stopped, the solenoids 13a and 13b are demagnetized, the electromagnetic direction switching valve 13 is positioned at the normal position S0, and the first and second load ports A , B communicate with the tank port T.

  Then, after the lapse of the predetermined time, even if the driving of the hydraulic pump 12 is stopped, the pressure of the hydraulic oil confined between the second pilot check valve 18 and the tip 17a of the second load line 17 is This is transmitted to the first pilot check valve 15 via the pilot line 21, and the first pilot check valve 15 continues to open. Accordingly, the hydraulic oil from the head side port 11c of the single acting cylinder 11 is discharged to the tank 23 via the first pilot check valve 15, the first load port A of the electromagnetic direction switching valve 13 and the tank port T. The single acting cylinder 11 continues to return.

  As described above, when the single-acting cylinder 11 performs the return operation, the first pilot check valve 15 is opened even if the hydraulic pump 12 is driven instantaneously and the hydraulic pump 12 is stopped thereafter. Subsequently, the single acting cylinder 11 continues to return.

  Thus, this hydraulic device can achieve energy saving because it does not drive the hydraulic pump 12 during most of the return operation of the single acting cylinder 11.

  Further, since the control device 32 controls the electromagnetic direction switching valve 13 to the demagnetized state when returning to the single acting cylinder 11 with the drive of the hydraulic pump 12 stopped, the electromagnetic direction switching valve 13 is controlled. The energy can be saved by the amount of electricity that is not energized.

  On the other hand, when the single-acting cylinder 11 is moved forward, the direction switching valve 13 is positioned at the position S2 so that the pump port P and the first load port A communicate with each other, and the tank port T and the second load port B are communicated. And the pump 12 is driven.

  Then, the pressurized hydraulic fluid from the pump 12 passes through the pump port P and the first load port A, the first pilot check valve 15 and the first load line 14 of the directional switching valve 13, and the single-acting cylinder 11, the single acting cylinder 11 is moved forward.

  At this time, since the pilot line 22 of the second pilot check valve 18 is connected to the first load line 14, the second pilot check valve 18 is opened by the high pilot pressure from the first load line 14. . Therefore, the high-pressure hydraulic oil confined between the second pilot check valve 18 and the tip 17a of the second load line 17 during the return operation is transferred to the second load port B and the tank port of the direction switching valve 13. It is discharged to the tank 23 via T.

  Next, when the driving of the pump 12 is stopped and the forward movement of the single acting cylinder 11 is stopped, the high pressure confined between the second pilot check valve 18 and the tip 17a of the second load line 17 is stopped. Since the hydraulic oil is already discharged to the tank 23, high pilot pressure does not act on the first pilot check valve 15, and the first pilot check valve 15 is closed to prevent backflow. The single acting cylinder 11 is held in a stopped state.

  Thus, during the forward movement of the single acting cylinder 11, the pressure of the first load line 14 acts on the second pilot check valve 18 as a high pilot pressure via the pilot line 22, and the second pilot check valve 18 is opened, and the high pressure hydraulic oil confined between the second pilot check valve 18 and the tip 17a of the second load line 17 has already been discharged to the tank 23. When the forward movement of the single-acting cylinder 11 is stopped, the first pilot check valve 15 does not receive high pilot pressure, so it is closed securely to prevent backflow, and the single-acting cylinder 11 is closed. It can be reliably held in a stopped state.

(Second Embodiment)
FIG. 2 is a circuit diagram of the hydraulic apparatus according to the second embodiment. The same components as those in FIG. 1 are denoted by the same reference numerals as those in FIG. Only the elements are described below.

  The hydraulic apparatus of the second embodiment is different from the hydraulic apparatus of the first embodiment in that a two-position single solenoid type directional switching valve 43 is used.

  According to the hydraulic device, when the single-acting cylinder 11 is returned, the control device 42 controls the motor 31 until the timer 35 counts the predetermined time after the timer 35 starts driving the hydraulic pump 12. The hydraulic pump 12 is driven, the solenoid 43a is demagnetized so that the electromagnetic direction switching valve 43 is positioned at the position S1, and the pump port P and the second load port B are communicated, and the first load port A and the tank port T Are communicated to each other, and after the predetermined time has elapsed, the driving of the motor 31 is stopped, the driving of the hydraulic pump 12 is stopped, and the demagnetization of the solenoid 43a is continued.

  Then, after the lapse of the predetermined time, even if the driving of the hydraulic pump 12 is stopped, the pressure of the hydraulic oil confined between the second pilot check valve 18 and the tip 17a of the second load line 17 is This is transmitted to the first pilot check valve 15 via the pilot line 21, and the first pilot check valve 15 continues to open. Accordingly, the hydraulic oil from the head side port 11c of the single acting cylinder 11 is discharged to the tank 23 via the first pilot check valve 15, the first load port A of the electromagnetic direction switching valve 43 and the tank port T. The single acting cylinder 11 continues to return.

  As described above, when the single-acting cylinder 11 performs the return operation, the first pilot check valve 15 is opened even if the hydraulic pump 12 is driven instantaneously and the hydraulic pump 12 is stopped thereafter. Subsequently, the single acting cylinder 11 continues to return.

  Thus, this hydraulic device can achieve energy saving because it does not drive the hydraulic pump 12 during most of the return operation of the single acting cylinder 11.

  Furthermore, since the control device 42 controls the electromagnetic direction switching valve 43 to the demagnetized state during the entire period in which the single-acting cylinder 11 returns to the operation, energy can be saved significantly.

  On the other hand, when the single-acting cylinder 11 is moved forward, the direction switching valve 43 is positioned at the position S2, the pump port P and the first load port A are communicated, and the tank port T and the second load port B are communicated. And the pump 12 is driven.

  Then, the pressurized hydraulic oil from the pump 12 passes through the pump port P and the first load port A, the first pilot check valve 15 and the first load line 14 of the direction switching valve 43, and the single acting cylinder. 11, the single acting cylinder 11 is moved forward.

  At this time, since the pilot line 22 of the second pilot check valve 18 is connected to the first load line 14, the second pilot check valve 18 is opened by the high pilot pressure from the first load line 14. . Therefore, the high-pressure hydraulic oil confined between the second pilot check valve 18 and the tip 17a of the second load line 17 during the return operation is transferred to the second load port B and the tank port of the direction switching valve 13. It is discharged to the tank 23 via T.

  Next, when the driving of the pump 12 is stopped and the forward movement of the single acting cylinder 11 is stopped, the high pressure confined between the second pilot check valve 18 and the tip 17a of the second load line 17 is stopped. Since the hydraulic oil is already discharged to the tank 23, high pilot pressure does not act on the first pilot check valve 15, and the first pilot check valve 15 is closed to prevent backflow. The single acting cylinder 11 is held in a stopped state.

  Thus, during the forward movement of the single acting cylinder 11, the pressure of the first load line 14 acts on the second pilot check valve 18 as a high pilot pressure via the pilot line 22, and the second pilot check valve 18 is opened, and the high pressure hydraulic oil confined between the second pilot check valve 18 and the tip 17a of the second load line 17 has already been discharged to the tank 23. When the forward movement of the single-acting cylinder 11 is stopped, the first pilot check valve 15 does not receive high pilot pressure, so it is closed securely to prevent backflow, and the single-acting cylinder 11 is closed. It can be reliably held in a stopped state.

(Third embodiment)
FIG. 3 is a circuit diagram of the hydraulic apparatus according to the third embodiment. The same components as those in FIG. 1 are denoted by the same reference numerals as those in FIG. Only the elements are described below.

  In the hydraulic apparatus of the third embodiment, the first pressure sensor 20 is connected to the second load line 17 between the second pilot check valve 18 and the tip 17 a of the second load line 17.

  Further, the control device 52 receives a signal indicating the pressure detected by the first pressure sensor 20 when the single-action cylinder 11 is returned to operate, and the pressure at which the first pressure sensor 20 opens the first pilot check valve 15. The hydraulic pump 12 is driven by the motor 31 until the above pressure, specifically, the opening pressure or a pressure slightly higher than that is detected. In other respects, the control device 52 has the same configuration as the control device 32 of the first embodiment and operates in the same manner.

  According to the hydraulic device, the first pressure sensor 20 detects the pressure of the hydraulic oil in the second load line 17 between the second pilot check valve 18 and the tip 17 a of the second load line 17. The control device 52 counts a predetermined time after the timer 35 starts driving the hydraulic pump 12 when the single-acting cylinder 11 is returned and the first pressure sensor 20 Since the hydraulic pump 12 is driven by the motor 31 until the pressure at which the first pilot check valve 15 is opened or a pressure slightly higher than that is detected, the second pilot check valve 18 and the tip 17a of the second load line 17 are driven. The pressure of the hydraulic oil in the second load line 17 between the first pilot check valve 15 and the first pilot check valve 15 can be reliably set to a pressure that can be opened.

  As described above, the drive of the hydraulic pump 12 is controlled by the AND of the completion of the timer 35 and the detection of the opening pressure of the first pilot check valve 15 of the first pressure sensor 20. The pressure downstream of the second pilot check valve 18 can be reliably controlled by the pressure that can open the first pilot check valve 15.

  However, the operation of the timer 35 may be stopped and the drive of the hydraulic pump 12 may be controlled only by the output of the first pressure sensor 20.

  The hydraulic apparatus according to the third embodiment can also achieve energy saving because it does not drive the hydraulic pump 12 during most of the return operation of the single acting cylinder 11.

  Further, the control device 52 controls the electromagnetic direction switching valve 13 to the demagnetized state when returning to the single-acting cylinder 11 with the drive of the hydraulic pump 12 stopped. The energy can be saved by the amount of electricity that is not energized.

(Fourth embodiment)
FIG. 4 is a circuit diagram of a hydraulic apparatus according to the fourth embodiment. The same components as those in FIG. 3 are denoted by the same reference numerals as those in FIG. Only the elements are described below.

  The hydraulic device according to the fourth embodiment is suitable when the line (pipe) between the pump port P of the electromagnetic directional control valve 13 and the second pilot check valve 18 is short and there is almost no delay in the pressure increase. Is applicable.

  A second pressure sensor 30 is connected to a pump line 19 that connects the hydraulic pump 12 and the pump port P of the electromagnetic direction switching valve 13.

  When the controller 52 returns the single-acting cylinder 11, the second pressure sensor 30 is set to a pressure higher than the pressure at which the first pilot check valve 15 is opened. The motor 31 is controlled to drive the hydraulic pump 12 until a slightly high pressure is detected.

  According to the hydraulic device, the control device 52 counts a predetermined time after the timer 35 starts driving the hydraulic pump 12 when the single-acting cylinder 11 is returned, and the second operation is performed. Since the hydraulic pump 12 is driven by the motor 31 until the pressure sensor 20 detects the pressure at which the first pilot check valve 15 is opened or slightly higher than that, the second pilot check valve 18 and the second load are driven. The pressure of the hydraulic fluid in the second load line 17 between the tip 17a of the line 17 can be reliably set to a pressure that opens the first pilot check valve 15.

  In this manner, the hydraulic pump 12 is driven by the AND of the completion of the time measurement of the timer 35 and the detection of the pressure higher than the pressure for opening the first pilot check valve 15 of the second pressure sensor 30. Therefore, the pressure on the downstream side of the second pilot check valve 18 can be reliably controlled by the pressure that can open the first pilot check valve 15.

  However, the operation of the timer 35 may be stopped and the drive of the hydraulic pump 12 may be controlled only by the output of the second pressure sensor 30.

  The hydraulic device of the fourth embodiment can also achieve energy saving because it does not drive the hydraulic pump 12 during most of the return operation of the single acting cylinder 11.

  Further, the control device 52 controls the electromagnetic direction switching valve 13 to the demagnetized state when returning to the single-acting cylinder 11 with the drive of the hydraulic pump 12 stopped. The energy can be saved by the amount of electricity that is not energized.

(Fifth embodiment)
FIG. 5 is a circuit diagram of the hydraulic apparatus according to the fifth embodiment. Components identical to those in FIGS. 3 and 4 are designated by the same reference numerals as those in FIGS. 3 and 4 and description thereof is omitted. Only different components will be described below.

  When the controller 62 returns the single-acting cylinder 11, the first and second pressure sensors 20, 30 have a pressure equal to or higher than the pressure at which the first pilot check valve 15 is opened. Alternatively, the hydraulic pump 12 is controlled to be driven by the motor 31 until a slightly higher pressure is detected.

  According to the hydraulic device, the control device 62 counts a predetermined time after the timer 35 starts driving the hydraulic pump 12 when the single-action cylinder 11 is returned, and the first device Since the hydraulic pump 12 is driven by the motor 31 until the second pressure sensors 20 and 30 detect a pressure at which the first pilot check valve 15 is opened or a pressure slightly higher than that, the second pilot check valve The pressure of the hydraulic fluid in the second load line 17 between 18 and the tip 17a of the second load line 17 can be set to a pressure that can reliably open the first pilot check valve 15.

  In this way, by the completion of the measurement of the predetermined time of the timer 35 and the detection of the pressure higher than the pressure for opening the first pilot check valve 15 of the first and second pressure sensors 20, 30, Since the drive of the hydraulic pump 12 is controlled, the pressure on the downstream side of the second pilot check valve 18 can be reliably controlled by the pressure that can open the first pilot check valve 15.

  However, the operation of the timer 35 may be stopped and the drive of the hydraulic pump 12 may be controlled only by the outputs of the first and second pressure sensors 20 and 30.

  The hydraulic device of the fifth embodiment can also achieve energy saving because it does not drive the hydraulic pump 12 during most of the return operation of the single acting cylinder 11.

  Further, since the control device 62 controls the electromagnetic direction switching valve 13 to the demagnetized state when returning to the single acting cylinder 11 while the drive of the hydraulic pump 12 is stopped, the electromagnetic direction switching valve 13 is controlled. The energy can be saved by the amount of electricity that is not energized.

  FIGS. 6A, 6B and 6C are views showing a modification of the electromagnetic direction switching valve.

  The electromagnetic direction switching valve 73 shown in FIG. 6A is a three-position solenoid type, and is in the normal position, that is, in the center position S0, the first load port A, the second load port B, the pump port P, and the tank port. All T's communicate with each other.

  The electromagnetic direction switching valve 83 shown in FIG. 6B is a three-position solenoid type, and the first load port A and the tank port T communicate with each other at the center position S0.

  The electromagnetic direction switching valve 53 shown in FIG. 6C is a two-position single solenoid type. The electromagnetic direction switching valve 53 can be used in place of the two-position electromagnetic direction switching valve 43 of the second embodiment. In this case, however, the solenoid 53b of the electromagnetic direction switching valve 53 must be energized for the entire period in which the single-action cylinder 11 performs the return operation.

  In the first to fifth embodiments, the spring return type single action cylinder 11 is used. However, a gravity type single action cylinder that returns by heavy load gravity may be used.

  In the first to fifth embodiments, the fixed displacement hydraulic pump is used. However, a variable displacement hydraulic pump may be used.

  In the first to fifth embodiments, the pilot line 22 of the second pilot check valve 18 is connected to the second load between the first load port A of the electromagnetic direction switching valve 13 and the first pilot check valve 15. Although connected to the line 14, the pilot line of the second pilot check valve 18 may be connected to the downstream side of the first pilot check valve 15, although not shown.

  In the first to fifth embodiments, the timer 35 is built in the control devices 32, 42, 52, and 62. However, the timer 35 may be externally provided separately from the control devices 32, 42, 52, and 62.

  In the above description, the hydraulic device has been described as the hydraulic device, but the present invention can of course be applied to a hydraulic device using a water pump.

  Further, although the motor is used as the driving device, an engine may be used instead. Further, the motor may be constant speed or variable speed.

  Moreover, although the electromagnetic direction switching valve was used as the direction switching valve, an electromagnetic proportional direction switching valve or a manual direction switching valve may be used.

1 is a circuit diagram of a hydraulic apparatus according to a first embodiment of the present invention. It is a circuit diagram of the hydraulic apparatus of 2nd Embodiment of this invention. It is a circuit diagram of the hydraulic apparatus of 3rd Embodiment of this invention. It is a circuit diagram of the hydraulic apparatus of 4th Embodiment of this invention. It is a circuit diagram of the hydraulic apparatus of 5th Embodiment of this invention. It is a figure which shows the modification of an electromagnetic direction switching valve. It is a circuit diagram of the conventional hydraulic device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Single acting cylinder 12 Hydraulic pump 13, 43, 53, 73, 83 Electromagnetic direction switching valve 14 1st load line 15 1st pilot check valve 17 2nd load line 17a Tip 18 2nd pilot check valve 20, 30 Pressure sensor 31 Motor 32, 42, 52, 62 Control device 35 Timer

Claims (7)

A single acting cylinder (11);
Directional switching valves (13, 43, 53, 73, 83);
The first load port (A) is connected to the first load port (A) of the direction switching valve (13, 43, 53, 73, 83) and the single acting cylinder (11). A first pilot check valve (15) connected so that the flow from A) to the single acting cylinder (11) is forward;
The second load port is connected to the second load port (B) of the directional control valve (13, 43, 53, 73, 83) and the second load line (17) whose tip (17a) is blocked. A second pilot check valve (18) connected so that the flow from the first load line (17) to the tip (17a) is in the forward direction;
A pump (12) connected to a pump port (P) of the direction switching valve (13, 43, 53, 73, 83);
A tank (23) connected to the tank port (T) of the direction switching valve (13, 43, 53, 73, 83),
The pilot line (21) of the first pilot check valve (15) is connected between the second pilot check valve (18) and the tip (17a) of the second load line (17), while the second A hydraulic device, wherein a pilot line (22) of a pilot check valve (18) is connected to the first load line (14). The hydraulic device according to claim 1,
Control is performed so that the pump port (P) and the second load port (B) of the direction switching valve (13, 43, 53, 73, 83) communicate with each other when the single acting cylinder (11) is returned. At the same time, the pump (12) is instantaneously driven by the driving device (31), and then the driving device (31) is controlled to stop, the driving of the pump (12) is stopped, and A control device (32, 42, 52, 62) for returning to the single acting cylinder (11) in a state where the tank port (T) and the first load port (A) are in communication with each other.
A hydraulic apparatus comprising: The hydraulic device according to claim 2,
The direction switching valve (13, 43, 73, 83) is an electromagnetic direction switching valve (13, 43, 73, 83) having an excited state and a demagnetized state.
When the control device (32, 42, 52, 62) is returning to the single acting cylinder (11) in a state where the driving of the pump (12) is stopped, the electromagnetic direction switching valve (13 , 43, 73, 83) is controlled to a demagnetized state. The hydraulic device according to claim 2 or 3,
A first pressure sensor (20) for detecting the pressure of the second load line (17) between the second pilot check valve (18) and the tip (17a) of the second load line (17);
The control device (52, 62), when returning the single-acting cylinder (11), until the first pressure sensor detects a pressure equal to or higher than the pressure at which the first pilot check valve (15) is opened. A hydraulic device characterized in that the pump (12) is driven by the drive device (31). The hydraulic device according to claim 2 or 3,
A second pressure sensor (30) for detecting the pressure between the pump (12) and the pump port (P) of the direction switching valve (13);
The control device (52, 62) detects a pressure equal to or higher than a pressure at which the second pressure sensor (30) opens the first pilot check valve (15) when returning the single-acting cylinder (11). The hydraulic device is characterized in that the pump (12) is driven by the drive device (31) until it is done. The hydraulic device according to claim 4,
A second pressure sensor (30) for detecting the pressure between the pump (12) and the pump port (P) of the direction switching valve (13);
When the control device (62) causes the single-acting cylinder (11) to return, the first pressure sensor (20) and the second pressure sensor (30) open the first pilot check valve (15). The hydraulic device characterized in that the pump (12) is driven by the drive device (31) until a pressure higher than the pressure is detected. In the hydraulic apparatus as described in any one of Claim 2-6,
With a timer (35)
The control device (32, 42, 52, 62), when returning the single-acting cylinder (11), until the timer (35) counts a predetermined time, the drive device (31). The hydraulic device characterized by driving the pump (12).

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