JP4254682B2 - Crane hydraulic circuit - Google Patents

Description

The present invention relates to a hydraulic circuit for a crane in which pressure release control is performed to release residual pressure in a pressure line to a tank after the prime mover is stopped.

In FIG. 3, reference numeral 1 denotes an engine as a prime mover, and 2 denotes a hydraulic pump (control pump) as a control hydraulic source driven by the engine 1. The hydraulic capacity of the hydraulic pump 2 is controlled by a pump capacity. A cylinder 3 and a negative brake cylinder 4 constituting a negative brake of the winch are connected via first and second electromagnetic switching valves 5 and 6, respectively. T is a tank.

  Further, when a winch is installed as an external equipment on the boom of the crane, the negative brake cylinder 7 for the negative brake (hereinafter referred to as a second negative brake cylinder, the negative brake cylinder 4 is referred to as the first negative brake cylinder). Is connected to the hydraulic pump 2 via the quick coupler 8 and the third electromagnetic switching valve 9 which are detachable.

  Further, an accumulator 10 for reducing pressure fluctuations and pulsations is connected to the discharge side of the hydraulic pump 2. 11 is a relief valve.

  Each of the cylinders 3, 4, and 7 is configured as a spring-back single-acting cylinder.

  Further, each electromagnetic switching valve 5, 6, 9 is controlled by a controller (not shown), and when a working signal is inputted, a pressurizing position for supplying pressure to the cylinders 3, 4, 7 and a stop signal are inputted. Sometimes, the pressure is set to the pressure release position B where the pressure is released to the tank T.

  According to such a circuit configuration, when the engine 1 is stopped, the electromagnetic switching valves 5, 6, 9 are switched from the pressurization position A to the illustrated pressure release position B, so that the pressures of the cylinders 3, 4, 7 are increased. The tank T is pulled out.

  However, since the pressure line 12 connecting the hydraulic pump 2 and each of the electromagnetic switching valves 5, 6, 9 is not directly connected to the tank T, the control line (residual pressure) remains in the pressure line 12 even after the engine is stopped. ) Is contained and remains.

  This residual pressure gradually drops due to internal leaks from the hydraulic equipment constituting the circuit, but the speed of this pressure drop may be very slow depending on the number of hydraulic equipment and the internal leak performance.

  In particular, in a circuit provided with an accumulator 10 such as this circuit, a pressure drop corresponding to the pressure accumulation volume of the accumulator 10 is required in addition to the residual pressure for control, and therefore the pressure drop speed of the pressure line 12 is further slowed down. .

  Thus, for example, the following problems occur when the residual pressure drop is delayed.

(i) Problems with Winch Negative Brake An example of a winch motor circuit is shown in FIG. In the figure, 13 is a winch motor, 14 is a hydraulic pump (not shown) and a control valve provided between the winch motor 13, 15 is a counter balance valve, and the negative brake cylinder 4 is a winch motor when pressurized as shown. 13 is released from the braking portion and is brought into a brake-off state. When the pressure is released, the brake portion is pressed against the braking portion by a spring force and the brake is turned on. Reference numeral 16 denotes a drain line of the winch motor 13.

  In this circuit configuration, when the engine 1 of FIG. 3 is stopped, the second electromagnetic switching valve 6 for negative brake is switched from the pressurization position A to the pressure release position B by a signal from the controller, so that the cylinder pressure is reduced to the tank T And the first negative brake cylinder 4 is in a brake-on state. Thereby, since the winch motor 13 is held in a stopped state, the suspended load can be prevented from falling even when the suspended load is suspended in the air.

  However, there may be a sticking phenomenon in which the second electromagnetic switching valve 6 does not mechanically move from the pressurizing position (a). As a result, the engine 1 is stopped in a brake-off state.

  Even in this state, if the residual pressure in the pressure line 12 is quickly released to the tank T, the pressure in the negative brake cylinder 4 is also inside the hydraulic equipment (electromagnetic switching valves 5 and 6, relief valve 11 and hydraulic pump 2) constituting the circuit. There is no problem because it descends due to a leak and turns into a brake-on state.

  However, as described above, since the residual pressure drop rate is slow in the conventional circuit, the holding pressure in the circuit is released due to internal leakage of the winch motor 13 and the counter balance valve 15 in FIG. 4 before the brake is turned on. There is a risk that suspended loads cannot be held.

(ii) Problems related to attachment / detachment of the quick coupler 8 Since the quick coupler 8 cannot be attached / detached to / from the pressure line 12 under pressure, when the engine 1 is stopped and removed or attached, until the residual pressure drops. Therefore, the work efficiency is poor.

  To solve such a problem, as shown in FIG. 5, the pressure line 12 is connected to the tank T via the pressure release valve 17, and after the engine is stopped, the pressure release valve 17 is opened to release the residual pressure to the tank T. Can be considered.

  However, in this configuration, since a dedicated pressure release valve 17 must be added, the cost increases.

  In addition, there is no particular patent document as a prior art disclosed regarding the above problems.

  Therefore, the present invention provides a hydraulic circuit for a crane that can obtain the pressure releasing action of a pressure line at low cost by using existing equipment.

The invention according to claim 1, the hydraulic pump driven by a prime mover, a pump capacity control cylinder for controlling the pump displacement of the hydraulic pump, in a parallel state negative brake cylinder and to each other to constitute the negative brake winch, and The first and second solenoid valves controlled by the control means are connected to each other, and an accumulator is connected to a pressure line connecting the hydraulic pump and the first and second solenoid valves. And a second solenoid valve of a crane configured to switch between a pressurizing position for applying pressure to the pump displacement control cylinder and the negative brake cylinder and a depressurizing position for releasing the pressure of the cylinder to the tank. in the hydraulic circuit, said control means comprises a motor stop detection means for detecting the operation stop of the prime mover, this motor stop detection means When the stop of the prime mover is detected Te, by periodically turned on / off operation of the first solenoid valve, after the depressurization control removing the residual pressure of the upper Ki圧 force line to the tank, itself It is comprised so that the control power supply which is a power supply of may be turned off.

  According to a second aspect of the present invention, in the configuration of the first aspect, the control means includes a timer, and after the engine stops, the control power is turned off by the timer after a preset pressure release time has elapsed. is there.

  According to a third aspect of the present invention, in the configuration of the first aspect, the control means includes a residual pressure detecting means for detecting the pressure in the pressure line, and the control power is turned off when the residual pressure in the pressure line becomes equal to or lower than the set pressure. It is comprised as follows.

  According to a fourth aspect of the present invention, in the configuration according to any one of the first to third aspects, the control means includes an abnormality detection means for detecting that the second electromagnetic valve is stuck, and the abnormality detection means The pressure release control is performed on condition that the fixed state of the second electromagnetic valve is detected.

  According to a fifth aspect of the present invention, in the configuration according to any one of the first to fourth aspects, the control unit selects one of a pressure relief control effective state in which the pressure relief control is performed and a pressure relief control invalid state in which the pressure relief control is not performed. The pressure release control is provided on the condition that the pressure release control valid state is selected by the selection means.

According to the present invention, a hydraulic circuit for controlling the pump displacement and negative brake and having an accumulator, that is, a pressure drop corresponding to the accumulator accumulation volume is required in addition to the residual pressure for control, so the pressure drop of the pressure line is reduced. in slow hydraulic circuit, the driving motor stopping after the on / off the first usage to control depressurized after engine stop solenoid valve as the pressure relief valve for the pump capacity control without harm also operate (the first solenoid valve for controlling) to pull the tank residual pressure in pressure lines by actuating periodically turned on / off, be secured phenomenon occurs in the second electromagnetic valve for the negative brake control, the first solenoid valve By the repetitive switching action, the residual pressure in the pressure line can be quickly released to release the negative brake cylinder from the pressurized state, and the brake can be turned on .

  Further, it is not necessary to add a solenoid valve dedicated to pressure release, and the motor stop detection means can use an existing one used for other control purposes.

  Also, in terms of software, it is only necessary to change the program of the control means so that the power can be secured only during the pressure release control. For this reason, the pressure release action can be obtained at low cost.

  In addition, since the power of the control means is automatically turned off after depressurization, it is possible to prevent waste of electric power (battery consumption) and power supply such as a configuration in which the solenoid valve is manually turned on and off. There is no risk of forgetting to cut.

  In this case, the automatic depressurization operation may be performed for the time set by the timer as in the invention of claim 2, or the residual pressure in the pressure line is detected by the pressure sensor as in the invention of claim 3. It is good also as a structure which turns off a power supply after completion of pressure release.

  According to the invention of claim 2, since the pressure sensor is not required, the intended purpose of cost reduction is met.

  On the other hand, according to the third aspect of the invention, the power is turned off when the depressurization is actually completed, so that useless power consumption can be suppressed. Further, there is no possibility that the depressurization control stops with the lapse of time while the depressurization is not completed.

By the way, the problem related to the negative brake of the winch occurs only when a sticking phenomenon occurs in the electromagnetic valve ( second electromagnetic valve ) that controls the negative brake cylinder. In other words, in the state where the sticking phenomenon has not occurred, the cylinder pressure is drawn into the tank as usual, and the brake is turned on quickly, so the suspended load does not drop even if the residual pressure drop is slow. There is no need to positively release the residual pressure.

In this regard, according to the fourth aspect of the invention, the pressure release control by the first solenoid valve is performed on the condition that the second solenoid valve is stuck (the pressure relief control is not performed unless the sticking has occurred). , it is possible to suppress the power consumption.

  Further, according to the invention of claim 5, since the validity / invalidity of the depressurization control can be arbitrarily selected, for example, in a circuit having an optional actuator that is attached / detached by the quick coupler, the invalidity is disabled when the quick coupler is not required to be attached / detached. By selecting, useless pressure relief control is not performed, so that power consumption can be suppressed.

  In the following embodiment, since the configuration of the hydraulic circuit portion is the same as that of the conventional circuit shown in FIG. 3, the same portions are denoted by the same reference numerals as those in FIG.

As a configuration common to the first embodiment shown in FIG. 1 and the second embodiment shown in FIG. 2, a pump displacement control cylinder 3 is controlled which is an electromagnetic valve that does not cause actual harm even if it is turned on / off after the engine is stopped. The first electromagnetic switching valve (the first electromagnetic valve in claim 1) 5 is also used as a pressure relief valve, and after the engine is stopped, the first electromagnetic switching valve 5 is turned on / off at a constant period to perform the pressure relief action. After that, the controller 18 constituting the control means is configured to be turned off.

1st Embodiment (refer FIG. 1)
As a standard equipment for the crane, a controller 18, an engine rotation sensor 19 for detecting the rotation of the engine 1, a key switch 20 for starting / stopping the engine 1, an alternator 21, and the alternator 21 are generating power. A power generation detection relay 22 for detecting the battery 23, a battery 23, and a battery relay 24 for supplying / cutting off the electric power of the battery 23 to the controller 18 are provided.

  The controller 18 receives an engine rotation signal from the engine rotation sensor 19, an operation signal of the key switch 20, and a power generation signal passing through the contact 22 a of the power generation detection relay 22, and determines engine stop based on this.

  It should be noted that the engine stop may be determined based on only one of the above signals (for example, the engine rotation signal), or may be determined by ANDing a plurality of signals.

  Further, as a component unique to this circuit, a timer 25 for determining a pressure release time is provided in the controller 18, and the second electromagnetic switching valve 6 (second electromagnetic valve in claim 1 together with the third electromagnetic switching valve 9) and A pressure sensor 27 as an abnormality detecting means for detecting the pressure of the negative brake cylinder circuit 26 connecting the first negative brake cylinder 4 (whether or not the electromagnetic switching valve 6 is stuck), and whether the pressure release control is valid / invalid. A selection switch 28 for selection is provided.

  The operation of this circuit will be described.

During rotation of the engine While the engine 1 is rotating, the electromagnetic switching valves 5, 6, 9 are set to the pressurizing position A by an operation signal from the controller 18.

  Further, since an operation signal (excitation current) is sent from the controller 18 to the battery relay 24 and the contact 24a of the relay 24 is closed, power supply to the controller 18 is ensured. The battery relay 24 is also excited by an operation signal from the key switch 20 and a power generation signal from the alternator 21.

Engine stop When the engine 1 stops, the electromagnetic switching valves 5, 6, 9 are switched from the pressurization position A to the pressure release position B based on a stop signal from the controller 18. As a result, the pressure of each cylinder 3, 4, 7 is released to the tank T.

  However, since the pressure line 12 is not directly connected to the tank T, the pressure is confined in the line 12 (residual pressure is generated).

  Here, the timer 25 is started from the engine stop point, and the operation signal is continuously output from the controller 18 to the battery relay 24 within a preset pressure release time.

  Therefore, since the contact 24a of the battery relay 24 remains closed, the power source of the controller 18 is maintained.

  When this pressure release time is entered, the controller 18 sends an on / off signal to the first electromagnetic switching valve 5 for the pump displacement control cylinder 3 at a constant cycle. As a result, the first electromagnetic switching valve 5 is alternately switched between the pressurization position A and the pressure release position B.

  By this repeated switching action, the pump capacity control cylinder circuit in which the pressure line 12 connects the first electromagnetic switching valve 5 and the pump capacity control cylinder 3 (first hydraulic actuator in claim 1) via the switching valve 5. 29, the residual pressure in the pressure line 12 is released to the tank T via the first electromagnetic switching valve 5 by so-called respiration. For this reason, the residual pressure of the pressure line 12 falls quickly.

  Therefore, even if an electromagnetic switching valve other than the first electromagnetic switching valve 5, that is, the second electromagnetic switching valve 6 or the third electromagnetic switching valve 9 is mechanically moved from the pressurizing position (a), the remaining phenomenon remains. The first negative brake cylinder 4 or the second negative brake cylinder 7 (the second hydraulic actuator in claim 1) turns to the brake-on state in a short time due to the rapid pressure drop.

  Therefore, the winch motor 13 can be reliably stopped and held by the negative brake before the suspended load cannot be held due to internal leak in the winch motor circuit shown in FIG.

  When the depressurization time elapses, the operation signal from the controller 18 to the battery relay 24 is stopped, whereby the relay contact 24a is opened, and the power supply from the battery 23 to the controller 18 is automatically stopped.

In this way, pressure release control after engine stop is performed using the first electromagnetic switching valve 5 as a pressure release valve for the existing pump displacement control, which does not cause any harmful effects even if it is repeatedly turned on / off in the engine stop state. Therefore, even if a sticking phenomenon occurs in the second electromagnetic switching valve 6 or the third electromagnetic switching valve 9, the residual pressure in the pressure line can be removed and the second hydraulic actuator can be released from the pressurized state.

  On the other hand, there is no need to add a dedicated pressure release valve 17 as shown in FIG. Further, as a means for detecting the stop of the engine 1 which is a precondition for performing the pressure relief control, an existing one (engine rotation sensor 19 or the like) used for other control purposes can be used.

  Furthermore, from the viewpoint of software, it is only necessary to change the program of the controller 18 so that the controller power supply can be secured only during the pressure release control.

  For this reason, the pressure release action can be obtained at low cost.

  In addition, since the controller 18 is automatically turned off after the pressure is released, it is possible to prevent waste of power (consumption of the battery 23) and to manually turn on / off the first electromagnetic switching valve 5. There is no risk of forgetting to turn off the power.

  Further, since the automatic depressurization operation is performed for the time set by the timer 25, a sensor (for example, a pressure sensor) for determining the stoppage of the depressurization operation becomes unnecessary, and the cost can be reduced.

  By the way, if the sticking phenomenon does not occur in the second electromagnetic switching valve 6, it is not necessary to positively perform the above-described pressure release control. It is also convenient if execution or non-execution of the pressure relief control can be determined according to the operator's intention and work situation (for example, whether or not the quick coupler 8 needs to be attached / detached).

  Therefore, in this embodiment, on condition that the selection switch 28 is turned on (it is selected to perform the pressure relief control) or that the sticking phenomenon occurs in the second electromagnetic switching valve 6. It is comprised so that said depressurization effect | action may be performed.

  That is, during engine operation, a pressure higher than a certain level is generated in the first negative brake cylinder circuit 26 by the pressure sensor 27 even though the switching signal is not output from the controller 18 to the second electromagnetic switching valve 6. When this is detected, it is determined that a sticking phenomenon has occurred in the switching valve 6, and pressure release control is executed.

  Regardless of the occurrence of the sticking phenomenon, the pressure release control is executed if the selection switch 28 is turned on, and the pressure release control is executed if the sticking phenomenon occurs even if the selection switch 28 is turned off.

  In other words, the pressure release control is not executed except when the sticking phenomenon occurs or when the selection switch 28 is turned on. With this conditional control, power consumption can be suppressed.

Second embodiment (see FIG. 2)
Only differences from the first embodiment will be described.

  In the first embodiment, after the engine is stopped, the pressure relief control is performed only for a preset pressure relief time, whereas in the second embodiment, the remaining pressure in the pressure line 12 is not the time but the safety or work. Therefore, the pressure relief control is performed until a value that does not cause a problem in terms of performance (for example, a pressure at which the negative brake turns on or a pressure at which the quick coupler 8 can be detached) is obtained.

  That is, a pressure sensor 30 as a residual pressure detecting means for detecting the pressure in the pressure line 12 is provided, and a pressure signal from the sensor 30 is input to the controller 18.

  When the residual pressure drops to a preset pressure based on the sensor signal after the start of the pressure release control, the controller 18 stops outputting the operation signal to the battery relay 24 as the pressure release is completed, Cut off.

  According to this configuration, since the power is turned off when the depressurization is actually completed, wasteful power consumption can be suppressed. Further, there is no possibility that the depressurization control stops with the lapse of time while the depressurization is not completed.

Other embodiments
(1) The solenoid valve of depressurization control serves not only to the electromagnetic switching valve mentioned in the above embodiment may utilize electromagnetic proportional valve.

(2) In the above-described embodiment, the selection switch 28 is used to select whether the pressure relief control is valid / invalid. However, the selection switch 28 is omitted, and after the engine is stopped, or the electromagnetic switching valve is stuck. The pressure release control may be performed on the condition of occurrence.

It is a circuit block diagram which shows 1st Embodiment of this invention. It is a circuit block diagram which shows 2nd Embodiment of this invention. It is a hydraulic control circuit diagram for demonstrating the problem of a prior art. It is a winch motor circuit diagram for demonstrating the problem of a prior art. It is another hydraulic control circuit diagram for demonstrating the problem of a prior art.

Explanation of symbols

1 engine 2 hydraulic pump 3 pump capacity control cylinder 4,7 Ne gas brake cylinder 5 first electromagnetic switching valve (first solenoid valve)
6 Second electromagnetic switching valve (second electromagnetic valve) to be detected
DESCRIPTION OF SYMBOLS 12 Pressure line 18 Controller which comprises control means 19 Engine rotation sensor as engine stop detection means 20 Same as above, Key switch 22 Same as above, Power generation detection relay 23 Battery 24 Battery relay for controlling controller power supply 25 Timer 27 Adherence of electromagnetic switching valve Pressure sensor as abnormality detecting means for detecting state 28 Selection switch as selecting means 30 Pressure sensor as residual pressure detecting means

Claims (5)

A hydraulic pump driven by a prime mover, a pump capacity control cylinder for controlling the pump displacement of the hydraulic pump, in a parallel state negative brake cylinder and to each other to constitute the negative brake winch, and are controlled by respective control means An accumulator is connected to the pressure line connecting the hydraulic pump and the first and second solenoid valves, and is connected via the first and second solenoid valves. The first and second solenoid valves are In the hydraulic circuit of the crane configured to switch between a pressurizing position for applying pressure to the pump displacement control cylinder and the negative brake cylinder and a pressure releasing position for extracting the pressure of the cylinder to the tank, the control means Comprises a prime mover stop detection means for detecting the stoppage of the prime mover, and the prime mover stop detection means stops the prime mover. When issued, by periodically turned on / off operation of the first solenoid valve, after the depressurization control removing the residual pressure of the upper Ki圧 force line to the tank, the control is its own power supply A crane hydraulic circuit characterized by being configured to turn off the power.   2. The crane hydraulic circuit according to claim 1, wherein the control means includes a timer, and is configured to turn off the control power after a preset pressure release time has elapsed after the engine has stopped. Crane hydraulic circuit.   2. The crane hydraulic circuit according to claim 1, wherein the control means includes a residual pressure detection means for detecting the pressure of the pressure line, and is configured to turn off the control power when the residual pressure of the pressure line becomes equal to or lower than a set pressure. The hydraulic circuit of the crane characterized by being made.   The crane hydraulic circuit according to any one of claims 1 to 3, wherein the control means includes an abnormality detection means for detecting that the second electromagnetic valve is stuck, and the abnormality detection means A crane hydraulic circuit configured to perform pressure relief control on condition that a fixed state of the second electromagnetic valve is detected.   5. The crane hydraulic circuit according to claim 1, wherein the control unit selects one of a pressure relief control effective state in which the pressure relief control is performed and a pressure relief control invalid state in which the pressure relief control is not performed. A crane hydraulic circuit characterized by comprising a selection means and configured to perform the pressure release control on condition that the pressure release control effective state is selected by the selection means.

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