JP2008190694A - Control device having auto-decel control function and control method thereof - Google Patents

Abstract

A control device having an auto-decel control function capable of obtaining a work speed at least equivalent to a work speed obtained when work is started from a conventional auto-decel control state is provided.
[Solution]
When the operation lever 11a is operated and the automatic deceleration control state is released, the rotational speed of the engine 2 increases from the automatic deceleration speed to a rotational speed set by a fuel dial or the like. At this time, the pressure oil accumulated in the accumulator 16 can be discharged to the discharge oil passage 25 by switching the charge valve 15 to the communication position. As a result, it is possible to supply the actuator with sufficient pressure oil for operating the actuator 10 without increasing the discharge amount from the variable displacement hydraulic pump 6. As a result, the auto-decel rotation speed can be made smaller than that of the prior art, and the fuel consumption during auto-decel control can be greatly improved.
[Selection] Figure 1

Description

  The present invention relates to a control device having an auto-decel control function for reducing an engine speed to an auto-decel speed after all operation levers are in a neutral state in a hydraulic circuit of a work vehicle, and a control method therefor.

  The hydraulic circuit of the working vehicle includes a hydraulic pump that uses an engine as a drive source, an actuator such as a hydraulic cylinder and a hydraulic motor, a control valve that controls supply and discharge of pressure oil to and from the actuator, and an operation lever that operates the control valve. Etc. are arranged. When performing various kinds of work in the work vehicle, the operator can control the control valve by operating the corresponding operation lever, and the discharge flow rate from the hydraulic pump can be controlled. By supplying the controlled discharge flow rate to the corresponding actuator, the operating speed of each actuator can be controlled.

  Conventionally, a hydraulic excavator as a work vehicle has been provided with a fuel dial for setting the engine speed. The operator can adjust the engine speed during idling by operating the fuel dial. Furthermore, the hydraulic oil required by the corresponding actuator can be discharged from the hydraulic pump in accordance with the differential pressure between the load pressure of the actuator and the discharge pressure from the hydraulic pump.

  Further, a hydraulic excavator will be described as an example of a working vehicle. Conventional hydraulic excavators are provided with an auto-decel control function. In the auto-decel control function, after a predetermined time has elapsed since all the control levers are in the neutral state, the engine is operated at a speed (auto-decel speed) smaller than the speed set with the fuel dial. It will be rotated.

  By operating this auto-decel control function, for example, even when the engine speed during idle operation set with the fuel dial is at the maximum speed, all control levers are in a neutral state. When a predetermined time elapses, the engine speed can be reduced from the maximum speed set by the fuel dial to the auto-decel speed.

  As a result, when the auto-decel control function is activated, i.e., after a predetermined time has elapsed since the excavator is not working, the engine speed during idle operation is reduced to the auto-decel speed. And fuel consumption of the engine can be reduced. Therefore, fuel efficiency can be improved during auto-decel control, and noise generated during no-load operation can be reduced.

  Further, when one of the operation levers in the neutral state is operated by the operator, the auto-decel control state is cancelled. When the auto-decel control state is released and the operation is resumed, the engine speed increases from the auto-decel speed to the high speed set by the fuel dial.

  In such a hydraulic excavator, among hydraulic excavator working machines constituted by a boom, an arm, and a bucket, an operator usually sets all operation levers in a neutral state with the bucket grounded to the ground. For this reason, when resuming the work, the worker first operates the boom lever in the “above boom” direction to perform the operation of raising the boom.

  At this time, if the auto-decel control state is canceled by performing an operation on the “boom” and the work is restarted, before the engine speed completely recovers to the high speed set by the fuel dial, The capacity of the variable displacement hydraulic pump driven by the engine will start to increase.

  For this reason, an abrupt load is applied to the engine that is trying to recover the engine speed to the high speed set with the fuel dial, which may cause engine noise or deteriorate the engine exhaust color. There will be problems such as trapping. Further, at this time, the boom ascending speed becomes slower than in the case where the auto-decel control is not performed, and there is a problem that the operator feels uncomfortable with the operation.

  In order to solve such problems in the auto-decel control of the engine, the pump load applied to the engine is not increased until a predetermined time elapses after the control for releasing the auto-decel control state is performed. An auto-decel control device (see Patent Document 1) that can increase the pump load applied to the engine has been proposed.

  In the auto-decel control device described in Patent Document 1, since the pump load is not increased until the engine speed reaches a high speed, an unreasonable load is applied to the engine whose speed is increased. Absent. For this reason, it is possible to greatly reduce the engine noise that has occurred when the auto-decel control state is released, and to prevent the exhaust color of the engine from deteriorating.

In addition, since a control for increasing the pump load is surely performed after a predetermined time from the release of the auto-decel control state, a series of civil engineering work and vehicle traveling can be moved quickly. As described above, since civil engineering work and vehicle traveling can be performed quickly, there is an advantage that work efficiency can be improved and an excellent driving feeling can be obtained.
JP-A-5-26069

  In the auto-decel control device described in Patent Document 1, the pump load applied to the engine is not increased until a predetermined time elapses after the auto-decel control state is released. For this reason, the operator cannot operate the work implement at a normal work speed or perform vehicle travel control at a normal travel speed until a predetermined time elapses.

  In order not to make the operator feel uncomfortable when the operation lever is operated from the auto-decel control state, for example, high idle speed can be set as the maximum engine speed during no-load operation of the engine. Assuming that the rotational speed of 2100 rpm was set, the auto-decel rotational speed was set at a rotational speed slightly lower than the conventionally used medium speed rotational speed of about 1400 rpm to 1500 rpm. In other words, the engine speed could only be reduced to an auto-decel speed that was approximately the medium speed.

  For this reason, for example, when 1000 rpm is set as the minimum rotation speed (low idle rotation speed) during no-load operation, the auto-decel rotation speed cannot be set to 1000 rpm. Even if the auto-decel speed is set to 1000 rpm, for example, in order for an operator to operate the operation lever to resume the operation from the auto-decel control state, the engine speed must be increased from the 1000 rpm state. I must.

  In addition, the engine speed of 1000 rpm is greatly different from the high idle speed of 2100 rpm. For this reason, the discharge amount discharged from the variable displacement hydraulic pump at the time of auto-decel control is an extremely small discharge amount compared to the discharge amount discharged from the variable displacement hydraulic pump at the time of non-auto-decel control.

  Further, for example, the time required to recover the engine speed to the rated speed (for example, the high idle speed 2100 rpm) after the worker resumes the work from the low idle speed 1000 rpm is the same as the conventional time. It takes longer than the time required to recover from the auto-decel rotation speed of the medium speed rotation speed of about 1400 rpm to 1500 rpm to the rated rotation speed.

  Therefore, the work speed of the work machine becomes slow, and the operation is uncomfortable. If it demonstrates in the example of the hydraulic shovel mentioned above, the boom raising speed which raises the bucket which was earth | grounded will become a slower raising speed than the conventional case. For this reason, the worker feels uncomfortable as compared with the normal boom raising operation.

  As described above, in the conventional hydraulic excavator, the auto-decel rotation speed cannot be set as a small rotation speed such as the minimum rotation speed during no-load operation. Therefore, in order to resume the work from the auto-decel control state and ensure a desired work machine speed, it is necessary to set the auto-decel rotation speed to a medium speed rotation speed (for example, about 1400 rpm).

  However, if the engine speed in the auto-decel control state can be reduced, for example, from a state of 1400 rpm to 1500 rpm to a state of 1000 rpm, there is sufficient room for further reducing the fuel consumption of the engine. However, as described above, when the engine speed in the auto-decel control state is reduced, the problem of uncomfortable feeling with respect to the work machine speed when operating the work machine from the time of auto-decel control cannot be solved. The fuel consumption of the engine could not be further reduced.

  The present invention has been made to solve the above-described conventional problems. A specific object of the present invention is to reduce the auto-decel rotation speed to a smaller rotation speed in a hydraulic circuit used in a work vehicle such as a hydraulic excavator. Set to improve fuel economy during auto-decel control, and when starting work from the auto-decel control state, make the work equipment speed equal to the work speed obtained when starting work from the conventional auto-decel control state It is an object of the present invention to provide a control device having an auto-decel control function and a control method thereof.

  The object of the present invention can be achieved by the inventions described in claims 1 to 9. The inventions described in claims 1 to 5 are inventions related to a control device having an auto-decel control function, and the inventions described in claims 6 to 9 are control devices described in claims 1 to 5. It is an invention of a control method using.

That is, the present invention includes at least one variable displacement hydraulic pump driven by an engine, at least one hydraulic actuator driven by discharge pressure oil from the variable displacement hydraulic pump, and the variable displacement hydraulic pump. A control valve that controls the discharged pressure oil and supplies and discharges the hydraulic actuator; and an operation lever that operates the control valve; and a control device that has an auto-decel control function for the engine,
An accumulator that discharges reinforcing pressure oil to the discharge pressure oil from the variable displacement hydraulic pump, and a charge valve that connects and disconnects the pressure oil discharged from the accumulator,
The control device is configured to control the charge valve to be in a communication state when releasing the auto-decel control and increasing the engine speed by operating the operation lever during auto-decel control. It has a feature.

  The present invention further includes a rotation speed setting unit that selects the two rotation speeds and sets the auto deceleration rotation speed, and cancels the automatic deceleration control from the low-speed auto deceleration rotation speed set by the rotation speed setting section. When the engine speed is increased, the charge valve is in a communication state, and the auto-decel control is canceled from the other auto-decel speed that is not set on the low-speed side set by the speed setting unit to reduce the engine speed. The main feature is that when the valve is raised, the charge valve is cut off.

Furthermore, the main feature of the present invention is that a configuration for setting two types of rotation speeds set as auto-decel rotation speeds is specified.
Furthermore, in the present invention, the main feature is that the configuration including the unload valve for controlling connection / disconnection of the discharge of the pressure oil discharged from the variable displacement pump to the tank and the operation mechanism of the unload valve are specified. ing.
In the present invention, the main feature is that the configuration using an open center type control valve having a center bypass circuit as a control valve is specified.

In the present invention, at least one variable displacement hydraulic pump driven by the engine, at least one hydraulic actuator driven by discharge pressure oil from the variable displacement hydraulic pump, and the variable displacement hydraulic pump discharged A control method of auto-decel control for the engine using a control device having a control valve that controls and supplies pressure oil to and from the hydraulic actuator, and an operation lever that operates the control valve,
Pressure oil accumulated in the accumulator when releasing the auto-decel control and increasing the engine speed by releasing the auto-decel control by operating the operation lever during auto-decel control Is released to the discharge pressure oil from the variable displacement hydraulic pump as another most important feature.

  In this control method, the autodecel rotation speed can be selected and set from two types of rotation speeds, and the pressure oil accumulated in the accumulator is changed according to the rotation speed selected as the autodecel rotation speed. The main feature is that the conditions for discharging to the discharge pressure oil from or forbidding the discharge are limited.

In the control method described above, the main feature is that the conditions for selecting the auto-decel rotation speed from two rotation speeds are specified.
Furthermore, in these control methods, the main feature is that the conditions for accumulating discharge pressure oil from the variable displacement hydraulic pump in the accumulator are specified.

  In the control device and control method having an auto-decel control function according to the present invention, when the auto-decel control state is canceled and the engine speed is increased from the auto-decel speed, the pressure is variable using the pressure oil accumulated in the accumulator. The discharge flow rate from the capacity type hydraulic pump can be reinforced.

  Thereby, even when the auto-decel rotation speed according to the present invention is set as the minimum rotation speed at the time of no load operation, for example, when releasing from the auto-decel control state, lower than the auto-decel rotation speed conventionally used, A sufficient amount of pressure oil can be supplied to the actuator by the reinforced pressure oil from the accumulator. For this reason, the working speed of the work implement can be obtained in a state in which the engine rotational speed is increased from the conventionally used auto-decel rotational speed and in a state that is not inferior.

  In this way, even if the engine speed is increased from the auto-decel speed, which is a low speed, the pump capacity of the variable displacement hydraulic pump is increased while the pressure oil accumulated in the accumulator is used. You don't have to. In addition, during this period, the pressure oil flow rate supplied to the actuator can be supplied to the actuator with substantially the same pressure oil flow rate as when the engine speed is increased from the conventional autodecel rotation speed.

  Therefore, in the present invention, even if the auto-decel rotation speed is set to a low-speed rotation speed lower than the conventional auto-decel rotation speed, the working machine speed obtained by increasing the engine speed from the auto-decel rotation speed is the engine speed from the conventional auto-decel rotation speed. A work implement speed equivalent to the work implement speed obtained when the rotation speed is increased can be obtained. Moreover, similarly to the auto-decel control device in Patent Document 1, engine noise can be reduced, and exhaust color deterioration can be prevented.

  In addition, when the auto-decel rotation speed can be selected and set from two kinds of rotation speeds, for example, the auto-decel rotation speed that has been conventionally used is set as it is as one auto-decel rotation speed. As the other rotation speed, for example, a minimum rotation speed during no-load operation (hereinafter referred to as a low idle rotation speed) can be set. Thereby, when the low idle rotational speed is selected and set as the automatic deceleration speed, the fuel consumption during the automatic deceleration control can be greatly improved.

  Moreover, when the engine speed is increased from the low idle speed, the pressure oil can be reinforced from the accumulator with respect to the discharge flow rate from the variable displacement hydraulic pump. As a result, a desired work speed can be given to the work implement from the beginning as in the case of using the conventionally used speed as the auto-decel speed. Therefore, the worker can operate the work implement without feeling uncomfortable with the operation. In addition, the work implement can be operated without being conscious of increasing the engine speed from the low idle speed.

  Further, the autodecel rotation speed can be automatically set from the two rotation speeds according to the pressure accumulated in the accumulator. In addition, when the accumulator pressure is low during auto-decel control, the pressure oil flow rate discharged from the variable displacement hydraulic pump can be used as the pressure oil for accumulating the accumulator.

  As a result, the accumulator can be kept in a state where the accumulator is always accumulated at a predetermined pressure or higher. Accordingly, the rotation speed on the low rotation speed side, for example, the low idle rotation speed can be greatly used as the auto deceleration rotation speed. In this way, the fuel consumption during auto-decel control can be greatly improved.

  Embodiments of the present invention will be described in detail below with reference to the drawings by way of examples. In addition, this invention is not limited to each Example demonstrated below, If it has a structure substantially the same as this invention and has the same effect, it applies suitably. Can be modified in various ways.

  FIG. 1 shows a hydraulic circuit relating to a control device mounted on a hydraulic excavator as an example of a control device having an auto-decel control function according to Embodiment 1 of the present invention.

The engine 2 is a diesel engine, and the engine output torque is controlled by adjusting the amount of fuel injected into the cylinder of the engine 2 by the fuel injection device 3. As the fuel injection device 3 for adjusting the fuel, a conventionally known fuel injection device can be used.
The engine 2 is provided with a rotation sensor 20 that detects the engine speed. That is, predetermined fuel is injected and supplied to the engine by the fuel injection device 3 in accordance with the command value of the fuel dial and the engine speed detected by the rotation sensor 20.

  A variable displacement hydraulic pump 6 (hereinafter referred to as a hydraulic pump 6) is connected to the output shaft 5 of the engine 2, and the hydraulic pump 6 is driven by the rotation of the output shaft 5. The tilt angle of the swash plate 6a of the hydraulic pump 6 is controlled by the pump control device 8, and the pump capacity D (cc / rev) of the hydraulic pump 6 changes as the tilt angle of the swash plate 6a changes.

  The pump control device 8 is controlled according to the differential pressure between the load pressure of the actuator 10 and the discharge pressure from the hydraulic pump 6. The tilt angle of the swash plate 6a in the hydraulic pump 6 is controlled by the pump control device 8, and the flow rate supplied to the actuator 10 is controlled by controlling the control valve 9 according to the operation amount of the operation lever 11a. Will be. The pump control device 8 can be configured by a known load sensing control device.

  The pressure oil discharged from the hydraulic pump 6 is supplied to the control valve 9 through the discharge oil passage 25. The control valve 9 is configured as a switching valve that can be switched to the 5-port 3 position by operating the operation lever 11a, and selectively supplies the pressure oil output from the control valve 9 to the oil passages 26a and 26b. . Then, the actuator 10 can be operated by the pressure oil output from the control valve 9.

  The actuator is not limited to the illustrated hydraulic cylinder type actuator, and may be a hydraulic motor, or may be configured as a rotary type actuator. In addition, only one set of control valve 9 and actuator 10 is illustrated, but multiple sets of control valve 9 and actuator 10 can be configured to operate multiple actuators with one control valve. It can also be configured to do so.

  That is, for example, if a hydraulic excavator is taken as an example of a working vehicle and an actuator is described, a boom hydraulic cylinder, an arm hydraulic cylinder, a bucket hydraulic cylinder, a left traveling hydraulic motor, a right traveling hydraulic motor, a turning motor, etc. Are used as actuators. In FIG. 1, among these actuators, for example, a boom hydraulic cylinder is shown as a representative.

  When the operation lever 11a is operated from the neutral position, pilot pressure is output from the operation lever device 11 according to the operation direction and the operation amount of the operation lever 11a. The output pilot pressure is applied to one of the left and right pilot ports of the control valve 9. As a result, the control valve 9 is switched from the (II) position, which is the neutral position, to the left and right (I) positions or (III) positions.

  When the control valve 9 is switched from the neutral (II) position to the (I) position, the discharge pressure oil from the hydraulic pump 6 can flow into the bottom side of the actuator 10 from the oil passage 26b. The piston can be extended. At this time, the pressure oil on the head side of the actuator 10 is discharged from the oil passage 26a through the control valve 9 to the tank 22.

  Similarly, when the control valve 9 is switched to the (III) position, the discharge pressure oil from the hydraulic pump 6 can flow into the head side of the actuator 10 from the oil passage 26a, and the piston of the actuator 10 is contracted. Can do. At this time, the pressure oil on the bottom side of the actuator 10 is discharged from the oil passage 26b to the tank 22 through the control valve 9.

  The oil passage 26b is provided with a lock valve 43 that prevents the boom from dropping naturally when the actuator 10 is a boom hydraulic cylinder. The lock valve 43 does not need to be provided depending on the configuration of the actuator 10. In FIG. 1, the lock valve 43 is illustrated in a simplified manner. However, when the actuator 10 extends, the check valve in the lock valve 43 is opened by the pressure oil output from the control valve 9 to the oil passage 26b. The pressure oil can flow into the bottom side of the actuator 10.

  When the actuator 10 is contracted, the opening degree of the check valve is controlled according to a pilot pressure (not shown) from the operation lever device 11, and the pressure oil on the bottom side of the actuator 10 is supplied to the tank via the control valve 9. Can be discharged to 22.

  The load pressure of the actuator 10 is taken out via the pilot oil passage 28, and the pump control device 8 is controlled as described above according to the differential pressure between the taken-out load pressure and the discharge pressure of the hydraulic pump 6.

  From the middle of the discharge oil passage 25, an oil passage 27a and an oil passage 27b branch off. In the illustrated example, the configuration in which the pressure sensor 30 is attached to the discharge oil passage 25 is shown, but the pressure sensor 30 may be attached to the oil passage 27a or the oil passage 27b.

  A charge valve 15, an accumulator 16 and a safety valve 17 are disposed on the oil passage 27 a, and the safety valve 17 is connected to the tank 22. Further, a pressure sensor 21 for detecting the pressure accumulated in the accumulator 16 (hereinafter referred to as accumulator pressure) is provided.

  The charge valve 15 is controlled by a pilot pressure from a proportional electromagnetic control valve 18 (hereinafter referred to as an electromagnetic control valve 18) controlled by the controller 7, and is switched between a position where the oil passage 27a is shut off and a position where it is communicated. It is done. That is, by controlling the charge valve 15, a part of the pressure oil discharged from the original pressure supply source 19a is accumulated in the accumulator 16, or the accumulation in the accumulator 16 is stopped, or conversely, The accumulated pressure oil can be discharged to the discharge oil passage 25, or the discharge of the pressure oil from the accumulator 16 to the discharge oil passage 25 can be stopped.

  The electromagnetic control valve 18 is supplied with pressure oil from the original pressure supply source 19a. In response to a control command from the controller 7, the electromagnetic control valve 18 can output the pressure oil supplied from the original pressure supply source 19a as a pilot pressure to the pilot oil passage 29a.

  An unload valve 12 is disposed between the oil passage 27b and the tank 22, and the unload valve 12 is switched between a position where the oil passage 27b is shut off and a position where the oil path 27b is communicated. The unload valve 12 has an unload cancel piston 13 (hereinafter referred to as cancel piston 13) controlled by a pilot pressure from a proportional electromagnetic control valve 14 (hereinafter referred to as electromagnetic control valve 14). ing. When the pilot pressure from the electromagnetic control valve 14 is acting on the cancel piston 13 via the pilot oil passage 29b, the unload valve 12 is held at the cutoff position.

  As the pressing force for switching the unload valve 12 to the communication position, the hydraulic pressure in the oil passage 27b acts, and as the pressing force for switching to the shut-off position, the pilot pressure and spring of the pilot oil passage 28 taking out the load pressure of the actuator 10 are used. Pressure is acting.

  The controller 7 is configured to receive detection signals from the pressure sensors 21, 23, and 30. The controller 7 can detect the operation state of the operation lever 11a based on the detection signal from the pressure sensor 23. Further, the detection signal from the pressure sensors 21 and 30 detects the hydraulic state in the discharge oil passage 25, the pressure accumulated in the accumulator 16, and the differential pressure between the pressure in the discharge oil passage 25 and the pressure of the accumulator 16. be able to.

  Further, the controller 7 stores in advance the autodecel rotation speed, the pressure that becomes the reference when the accumulator 16 starts accumulating pressure, and the like. These values are not particularly fixed values, and can be set as arbitrary values. Alternatively, it can be used by selecting from a plurality of preset values. For example, as the auto-decel rotation speed, two types of rotation speeds (1400 rpm) on the middle rotation side and rotation speed (1000 rpm) on the low rotation side are stored, and the auto-decel rotation is selected from the two rotation speeds. Number can be set.

  When the controller 7 determines that the pressure is insufficient and the flow rate is insufficient to operate the actuator 10 at the desired working speed with only the discharge pressure from the hydraulic pump 6, the controller 7 turns the electromagnetic control valve 18 off. The charge valve 15 can be switched to the communication position by control.

  Thus, the pressure oil accumulated in the accumulator 16 can be discharged to the discharge oil passage 25 as pressure oil that reinforces the discharge pressure oil from the hydraulic pump 6. When the pressure oil is discharged from the accumulator 16 to the discharge oil passage 25, the controller 7 detects that the pressure of the accumulator 16 has dropped below a predetermined pressure by the signal from the pressure sensor 21, the controller 7 controls the charge valve 15. Switch to the blocking position.

  According to the detection signal from the pressure sensor 23, the control valve 9 is switched to the neutral position and the actuator 10 maintains its operating position, and the detection signal from the pressure sensor 21 causes the pressure in the accumulator 16 to reach a predetermined pressure. When the controller 7 detects that the following is true, the controller 7 controls the electromagnetic control valve 14 to hold the unload valve 12 in the cutoff position.

  Further, the controller 7 controls the electromagnetic control valve 18 to bring the charge valve 15 into communication. Thereby, the discharge pressure oil from the hydraulic pump 6 can be used for accumulating the accumulator 16 without being wasted.

  When the controller 7 detects that the pressure accumulated in the accumulator 16 is equal to or higher than a predetermined pressure by the detection signal from the pressure sensor 21, the controller 7 controls the electromagnetic control valve 18 to shut off the charge valve 15. Switch to. At the same time, the controller 7 controls the electromagnetic control valve 14 to switch the unload valve 12 to the communication position. As a result, the pressure of the discharge oil passage 25 can be reduced to a low unload pressure. That is, the normal unload state is restored.

  The opening / closing control of the charge valve 15 will be described with reference to the control block shown in FIG. 6 and FIG. The controller 7 includes an operation signal (60) from the pressure sensor 23 that detects the operation state of the operation lever 11a, a sensor signal (61) from the pressure sensor 30 that detects the discharge pressure of the hydraulic pump 6, and a pressure accumulation state of the accumulator 16 The pressure sensor signal (62) from the pressure sensor 21 for detecting the above is inputted. Using these input signals, the charge valve opening / closing signal calculation unit (63) calculates a control signal for opening and closing the charge valve 15.

  That is, the charge valve open / close signal calculation unit (63) determines whether the operation lever 11a is operated or whether the operation lever 11a is maintained at the neutral position during the auto-decel control based on the operation signal (60). Do. When it is determined that the operation lever 11a has been operated from the neutral position, the charge valve open / close signal calculation unit (63) determines whether or not the pressure of the pressure sensor signal (62) in the accumulator 16 is equal to or higher than a desired pressure. Make a decision.

First, when the charge valve opening / closing signal calculation unit (63) determines that the operation lever 11a has been operated from the neutral position, and the pressure sensor signal (62) determines that the pressure is equal to or higher than the desired pressure, The charge valve open / close signal calculation unit (63) controls the charge valve 15 to communicate. At this time, the pressure accumulated in the accumulator 16 can be reinforced with respect to the discharge pressure from the hydraulic pump 6.
At the same time, the charge valve opening / closing signal calculation unit (63) determines the differential pressure between the sensor signal (61) in the hydraulic pump 6 and the pressure sensor signal (62) in the accumulator 16, and when the differential pressure becomes a predetermined pressure or less, Control is performed so that the charge valve 15 is disconnected from the communication control. That is, the reinforcement from the accumulator 16 is stopped.

  Next, in the charge valve opening / closing signal calculation unit (63), it is determined that the operation lever 11a is operated from the neutral position, and the pressure of the pressure sensor signal (62) is lower than the desired pressure. When it is determined, control is performed to keep the charge valve 15 shut off. At this time, reinforcement from the accumulator 16 is not performed.

  Further, when the charge valve opening / closing signal calculation unit (63) determines that the operation lever 11a is maintained at the neutral position and determines that the pressure of the pressure sensor signal (62) is equal to or higher than a desired pressure, A control signal for shutting off the charge valve 15 is created to keep the charge valve 15 in a shut-off state. At this time, neither the pressure accumulated in the accumulator 16 nor the pressure accumulated in the accumulator 16 is released.

  Further, the charge valve opening / closing signal calculation unit (63) determines that the operation lever 11a is maintained at the neutral position, and determines that the pressure of the pressure sensor signal (62) is lower than the desired pressure. In some cases, control is performed to allow the charge valve 15 to communicate, and the accumulator 16 is accumulated with the discharge pressure from the hydraulic pump 6. At the same time, in the charge valve opening / closing signal calculation unit (63), when it is determined from the pressure sensor signal (62) in the accumulator 16 that the pressure accumulated in the accumulator 16 exceeds the predetermined pressure, the charge valve 15 is controlled to communicate. Control to shut off. In this way, the accumulator 16 can store a pressure equal to or higher than a predetermined pressure, and preparations for reinforcing the hydraulic pump 6 from the next accumulator 16 can be prepared.

Next, a control method in the control device of the first embodiment will be described. Here, FIG. 2 is a flowchart showing a control flow of the first embodiment.
First, in step 1, the controller 7 receives the detection signal from the pressure sensor 23 and confirms the operation state of the operation lever 11a. Subsequently, in step 2, it is determined whether or not the operation lever 11a is in a neutral state, and when it is in a neutral state, an elapse of a predetermined time is confirmed and an auto-decel determination is performed.

  When there are a plurality of operation levers, it is determined whether all the operation levers are in a neutral state. In addition, when the operation lever 11a is in the neutral state, the transition to the auto-decel control can be performed, for example, by operating the operation button for starting the auto-decel without waiting for the elapse of a predetermined time. You can also. In the present invention, the shift to the auto-decel control is not limited to the one based on the passage of a predetermined time, but includes one in which the shift is performed by operating an operation button for starting the auto-decel.

  In this auto-decel determination, when it is determined that the operation lever 11a is in the neutral state, the operation on the hydraulic excavator is not performed, and that a predetermined time has elapsed since the operation lever 11a was in the neutral state, Next, the controller 7 performs the processing in step 3.

  In step 3, the pressure accumulated in the accumulator 16 (that is, the accumulator pressure) is detected by the pressure sensor 21, and whether or not the detected accumulator pressure is larger than the reference pressure P1 stored in advance. Make a decision. The value of the pressure P1 can be obtained in advance by experiments or the like.

  If it is determined in step 3 that the accumulator pressure is larger than the pressure P1, the process proceeds to step 4. If it is determined that the accumulator pressure is smaller than the pressure P1, the process proceeds to step 10 described later.

  In step 4, the controller 7 performs auto-decel control so that the engine speed becomes the auto-decel speed from the speed set by the fuel dial. The auto-decel rotation speed in step 4 is the low-speed auto-decel rotation speed (for example, 1000 rpm).

  At this time, the control valve 9 is held in the neutral position (II position) shown in FIG. 1, and the charge valve 15 is held in the shut-off position by the controller 7. The unload valve 12 is switched to the communication position by the hydraulic pressure in the second branch oil passage 27b. By switching the unload valve 12 to the communication position, it is possible to prevent the hydraulic pressure in the discharge oil passage 25 from becoming too high due to the pressure oil discharged from the hydraulic pump 6.

In step 4, after the engine speed is controlled to be the auto-decel speed, the process of step 5 is performed.
In step 5, the controller 7 performs a decel return determination. As the decelerating determination, based on the detection signal from the pressure sensor 23, it is determined whether or not the operation lever 11a has been operated from the neutral state.

  In step 5, the operation lever 11a is operated to switch the control valve 9 from the neutral position (II position) to the position (I) or (III) (that is, the operation of the hydraulic excavator is resumed). Is confirmed by the controller 7, the process proceeds to step 6.

In step 6, the controller 7 cancels the auto-decel control and increases the engine speed to the speed set by the fuel dial, for example, the rated speed. At the same time, the electromagnetic control valve 18 is controlled to switch the charge valve 15 to the communication position, and the pressure oil accumulated in the accumulator 16 is discharged to the discharge oil passage 25.
At this time, the load pressure of the actuator 10 acts on the unload valve 12, and the unload valve 12 is switched to the cutoff position.

  If the discharge flow rate from the accumulator 16 is increased, even if the discharge flow rate from the hydraulic pump 6 is small, the required flow rate required to operate the actuator 10 at a desired operating speed can be satisfied. Therefore, in this case, it is not necessary to increase the swash plate angle of the hydraulic pump 6 even if the operation lever 11a is operated, so that the load torque to the engine 2 can be reduced. Thus, the engine speed can be quickly increased from the auto-decel speed to, for example, the rated speed.

  Since the discharge flow rate of the accumulator 16 can be added to the discharge flow rate of the hydraulic pump 6, the autodecel rotation speed is reduced from the conventional medium speed (for example, 1400 rpm) to the low speed (for example, 1000 rpm). Can do. Moreover, even when the engine speed is increased from a low speed, for example, to the rated speed, the shortage of the pump discharge flow rate is compensated by the discharge amount from the accumulator 16 without increasing the discharge flow rate from the hydraulic pump 6. Can do.

  Therefore, it is possible to ensure at least a working speed equivalent to the case where the rotational speed is medium, such as the conventional auto-decel speed. If the discharge flow rate from the accumulator 16 is added to the discharge flow rate of the hydraulic pump 6 for a while even if the engine rotation speed exceeds the medium speed rotation speed (for example, 1400 rpm), the engine rotation speed can be increased more efficiently. For example, it can be quickly increased to the rated speed.

When the process in step 6 ends, the process proceeds to step 7.
In step 7, the controller 7 makes a determination on conditions 1 to 3 described below based on detection signals from the pressure sensor 21 and the pressure sensor 30. As the determination of Condition 1, it is determined whether or not the differential pressure between the pressure in the discharge oil passage 25 and the accumulator pressure is equal to or less than a predetermined value set in advance. Further, as the determination of the condition 2, based on the detection signal from the rotation sensor 20, it is determined whether or not the engine speed is equal to or higher than a predetermined value set in advance. Further, as the determination of the condition 3, it is determined whether or not a predetermined time set in advance has elapsed since the charge valve 15 was switched to the communication position.

  The reason for determining each of these conditions 1 to 3 is to determine the timing for blocking the release from the accumulator 16. That is, when the differential pressure between the pressure in the discharge oil passage 25 and the accumulator pressure in condition 1 is equal to or less than a predetermined value set in advance, that is, when the accumulator pressure approaches the pressure in the discharge oil passage 25, The need to increase the pressure in the discharge oil passage 25 with the accumulator pressure is reduced.

  Therefore, by using the condition 1, it is possible to determine the timing for shutting off the discharge from the accumulator 16, and the timing for shutting off can be determined by the differential pressure between the pressure in the discharge oil passage 25 and the accumulator pressure. it can.

  In condition 2, it is not necessary to reduce the load torque to the engine 2 if the engine speed increases to a preset speed or higher, and therefore it is possible to determine the timing for blocking the release from the accumulator 16. it can. Further, under condition 3, if the release from the accumulator 16 is performed for a predetermined time, the engine speed can be increased to a desired speed, so the timing for preventing further discharge from the accumulator 16 is determined. can do.

When it is confirmed in step 7 that any one of the conditions 1 to 3 is satisfied, the process proceeds to step 8.
In step 8, the controller 7 controls the electromagnetic control valve 18 to switch the charge valve 15 to the cutoff position. As a result, the discharge of the reinforcing flow rate from the accumulator 16 to the discharge oil passage 25 is stopped, and the actuator 10 is operated only by the discharge pressure oil from the hydraulic pump 6.
When the process of step 8 is completed, the process returns to step 1 and a series of processes starting from the process of confirming the operation state of the operation lever 11a is performed.

  Next, the case where it is determined in step 3 that the accumulator pressure is smaller than the preset pressure P1 will be described. That is, when the pressure actually accumulated in the accumulator 16 is smaller than the minimum pressure P1 that should be accumulated in the accumulator 16, the process proceeds to step 10.

  In step 10, when the pressure accumulated in the accumulator 16 is smaller than the pressure P1, auto-decel control is performed with the auto-decel rotation speed set to a medium speed rotation speed (for example, 1400 rpm). The auto-decel rotation speed is set to the medium-speed rotation speed when the auto-decel control is performed with the auto-decel rotation speed being, for example, a low-speed rotation speed of 1000 rpm, even when the pressure accumulated in the accumulator 16 is smaller than the pressure P1. This is because such a problem occurs.

  That is, even if the operation of the hydraulic excavator is resumed from the auto-decel rotation speed set to the low-speed rotation speed, the flow rate that can be discharged from the accumulator 16 is reduced, and the discharge amount from the hydraulic pump 6 cannot be sufficiently reinforced. For this reason, even if the discharge flow rate from the accumulator 16 is added, it is difficult to secure a flow rate sufficient to obtain a desired work implement speed.

  In other words, sufficient accumulator pressure is not accumulated in the accumulator 16 to increase the engine speed from at least the low speed to the medium speed. Therefore, in step 3, if the pressure accumulated in the accumulator 16 is equal to or higher than the pressure P1, sufficient pressure is accumulated to increase the engine speed from at least the low speed to the medium speed. Become. On the contrary, if the pressure accumulated in the accumulator 16 is smaller than the pressure P1, the pressure sufficient to increase the engine speed from at least the low speed to the medium speed is not accumulated.

  If the pressure accumulated in the accumulator 16 is smaller than the pressure P1, the process proceeds to Step 10, where the controller 7 sets the auto-deceleration speed to a medium speed (for example, 1400 rpm) and the engine 2 at this auto-deceleration speed. Auto-decel control is performed to control the operation.

  At this time, as in the case of the processing in step 4 described above, the control valve 9 shown in FIG. 1 holds the neutral position, and the charge valve 15 is held in the cutoff position. Further, the unload valve 12 is switched to the communication position, and the pressure oil discharged from the hydraulic pump 6 is discharged to the tank 22. By discharging the pressure oil discharged from the hydraulic pump 6 to the tank 22, it is possible to prevent the oil pressure in the discharge oil passage 25 from becoming too high.

  When the process of step 10 is performed, the process proceeds to step 11. In step 11, similarly to the processing in step 5 described above, the controller 7 determines whether or not the operation lever 11a has been operated from the neutral state by the operator based on the detection signal from the pressure sensor 23. I do.

  In step 11, the operation lever 11a is operated to switch the control valve 9 from the neutral position (II position) to the position (I) or (III) (that is, the operation of the hydraulic excavator is resumed). Is confirmed by the controller 7, the process proceeds to step 12.

  In step 12, the unload valve 12 is switched to the cutoff position by the load pressure of the actuator 10. Then, the actuator is driven only by the discharge pressure oil from the hydraulic pump 6.

  At this time, since the engine speed is increased from the auto-decel rotation speed set to a medium speed (for example, 1400 rpm), the work can be resumed at a desired work machine speed without reinforcement by the accumulator pressure. Can do. After performing the process in step 12, the process returns to step 1 and the series of processes from step 1 is performed.

On the other hand, if the operation of the operation lever 11a is not confirmed in step 11, the process proceeds to step 13. In step 13, the cancel piston 13 is operated to hold the unload valve 12 in the shut-off position, and the electromagnetic control valve 18 is controlled to switch the charge valve 15 to the communication position. As a result, the pressure oil discharged from the hydraulic pump 6 can be used for accumulating the accumulator 16 without being discharged to the tank 22. Accordingly, pressure accumulation in the accumulator 16 can be performed smoothly.
At this time, the state in which the accumulator 16 is accumulating can be detected by the pressure sensor 21.

  When the pressure is accumulated in the accumulator 16 at step 13, the process proceeds to step 14. In step 14, the controller 7 sets the accumulator pressure based on the detection signal from the pressure sensor 21 so that the pressure of the pressure oil accumulated in the accumulator 16 does not exceed a predetermined pressure P2. It is determined whether or not the pressure P2 or higher. The predetermined pressure P2 can be set as a pressure corresponding to the opening / closing pressure of the safety valve 17.

  If it is confirmed in step 14 that the accumulator pressure has become equal to or higher than the pressure P2, the process proceeds to step 15. In step 15, the controller 7 controls the electromagnetic control valve 18 to switch the charge valve 15 to the cutoff position, and stops accumulating in the accumulator 16.

  When the process of step 15 is performed, the process proceeds to step 4 where the auto-decel speed is reset from the medium speed (for example, 1400 rpm) set in step 10 to the low speed (for example, 1000 rpm). Perform auto-decel control for 2. As a result, the engine speed during auto-decel control can be kept low, and fuel consumption can be improved. After proceeding to step 4, the processing from step 5 described above is performed.

  On the other hand, the control when the operation lever 11a is operated before the accumulator pressure becomes equal to or higher than the pressure P2 in step 14 will be described as the control from step 16. In step 14, when the accumulator pressure is not equal to or higher than the pressure P2, the process proceeds to step 16.

In step 16, a decel return determination is performed to determine whether or not the operation lever 11a has been operated from the neutral position. As the decel recovery determination, the same determination as the determination in step 4 described above is performed. In step 16, when the operation of the operation lever 11a is not confirmed, the process returns to step 14 to repeat the determination as to whether or not the accumulator pressure is equal to or higher than the pressure P2.
It should be noted that pressure accumulation in the accumulator 16 is continuously performed while the deceleration recovery determination in step 16 is being performed.

  In step 16, if the operation of the operation lever 11a is confirmed, the process proceeds to step 17. In step 17, the engine speed is increased from the auto-decel rotation speed on the middle rotation side, the charge valve 15 is switched to the shut-off position, the pressure accumulation in the accumulator 16 is stopped, and the actuator 10 is only used by the discharge pressure oil from the hydraulic pump 6. The control which operates is performed. Then, after the process in step 17 is performed, the process returns to step 1 to perform a series of processes.

  As described above, in the present invention, the auto-decel rotation speed can be set low from the conventional medium speed to the low-speed speed, so that the fuel consumption at the time of auto-decel can be significantly reduced compared to the conventional one. Moreover, even if the engine speed is increased from the low-speed-side auto-decel speed to the rated speed, for example, the pressure oil accumulated in the accumulator can be released to reinforce the discharge flow rate from the hydraulic pump. it can.

  For this reason, it is possible to obtain a working machine speed that is equal to or higher than that when the engine speed is increased from the auto-decel rotation speed on the middle rotation side. That is, the work implement can be operated without slowing down the acceleration performance when operating the work implement.

  In addition, when the accumulator pressure is below a predetermined pressure, it can be set as a medium speed without reducing the auto deceleration speed to a low speed. It doesn't get worse.

  A control device and control method having an auto-decel control function according to Embodiment 2 of the present invention will be described. FIG. 3 shows an example of a control device mounted on a hydraulic excavator and shows a hydraulic circuit related to the control device.

  As a configuration in the second embodiment, the pressure oil accumulated in the accumulator 16 can be directly discharged to the actuator 10, and this configuration is different from the configuration in the first embodiment. In addition, with this configuration, in the circuit configuration in which the pressure oil accumulated in the accumulator 16 is directly discharged to the actuator 10, the configuration using the charge valve 45 instead of the charge valve 15 in the first embodiment, Have different circuit configurations.

Regarding other configurations, since the configuration is the same as that of the first embodiment, members having the same configuration as those of the first embodiment are denoted by the same reference numerals, and the description of the members is omitted. To do.
Further, the description in the second embodiment will be described focusing on a configuration different from the configuration of the hydraulic circuit 1 in the first embodiment described above.

  In the hydraulic circuit 41 of the second embodiment, a charge valve 45 as a directional switching valve that can be switched to a 4-port 3-position is disposed on an oil passage 27a that allows the discharge oil passage 25 and the accumulator 16 to communicate with each other. Yes. The first communication position shown as the position (IV) in FIG. 3 is a position where the discharge oil passage 25 and the accumulator 16 are communicated and the communication between the oil passage 26b communicating with the bottom side of the actuator 10 and the accumulator 16 is cut off. It has become.

The shut-off position shown as the (V) position is a position that shuts off the communication between the discharge oil passage 25 and the oil passage 26b and the accumulator 16. In this blocking position, the oil passage 26b communicates with the tank 22. Further, the second communication position shown as the (VI) position is a position where the communication between the discharge oil passage 25 and the accumulator 16 is cut off and the accumulator 16 and the oil passage 26b are communicated.
For example, when the actuator 10 is a boom hydraulic cylinder, the oil passage 26b is provided with a lock valve 43 that prevents the boom from dropping naturally.

  Further, in the hydraulic circuit 41 shown in FIG. 3, the tilt angle of the swash plate 6a of the hydraulic pump 6 is the difference between the load pressure of the actuator 10 and the discharge pressure of the hydraulic pump 6 as in the first embodiment. Is controlled accordingly. Further, in the second embodiment, the pressure oil accumulated in the accumulator 16 is discharged between the control valve 9 and the actuator 10 so that the extension operation of the actuator 10 can be reinforced.

  Proportional electromagnetic control valves 48a and 48b (hereinafter referred to as electromagnetic control valves 48a and 48b) are connected to the controller 47. The controller 47 can apply the pilot pressure output by controlling these electromagnetic control valves 48a and 48b to the charge valve 45 via the pilot oil passages 29a and 29a ′. As a result, the charge valve 45 can be switched to the first communication position (IV position), the cutoff position (V position), or the second communication position (VI position).

  Next, a control method in the hydraulic circuit 41 of the second embodiment will be described. Note that the control flow in the second embodiment is basically the same as the control flow in the first embodiment. Therefore, the control flow of the second embodiment will be described with reference to the control flow of the first embodiment shown in FIG.

  In the second embodiment, when the electromagnetic control valves 48a and 48b are controlled and the charge valve 45 is switched to the second communication position (VI position) in step 6, the pressure oil accumulated in the accumulator 16 through the oil passage 26b. Can be supplied to the bottom side of the actuator 10. As a result, the accumulator pressure can be directly used as a reinforcing pressure when the accumulator 10 is extended.

  In other words, in the first embodiment, the pressure oil accumulated in the accumulator 16 is discharged to the discharge oil passage 25 on the upstream side of the control valve 9. In contrast, in the second embodiment, the pressure oil accumulated in the accumulator 16 is directly discharged to the oil passage 26b communicating with the bottom side of the actuator 10. With this configuration, the loss of pressure oil due to passing through the control valve 9 is reduced, and the pressure oil discharged from the accumulator 16 can be effectively used for the operation of the actuator 10.

  Next, a control device and control method having an auto-decel control function according to Embodiment 3 of the present invention will be described. In FIG. 4 as well, a hydraulic circuit related to the control device is shown by taking a control device mounted on the hydraulic excavator as an example.

  In the hydraulic circuit 51 shown in FIG. 4, the control valve 59 disposed between the hydraulic pump 6 and the actuator 10 is configured as an open center type directional switching valve that can be switched to the 6-port 3 position. Further, a switching valve 52 for connecting and disconnecting the tank port of the control valve 59 and the tank 22 is provided. In these configurations, the configuration according to the third embodiment is different from the configuration according to the first embodiment.

Regarding other configurations, since the configuration is the same as that of the first embodiment, members having the same configuration as those of the first embodiment are denoted by the same reference numerals, and the description of the members is omitted. To do. The controller is indicated by reference numeral 57.
Further, the configuration of the hydraulic circuit 51 in the third embodiment will be described focusing on a configuration different from the configuration of the hydraulic circuit 1 in the first embodiment described above.

The control valve 59 is switched between a neutral position (II position) and a communication position (left and right (I) position or (III) position) according to the operation of the operation lever 11a.
When the control valve 59 is held at the neutral position (II position), the operation of the actuator 10 can be stopped, and the discharge hydraulic oil from the hydraulic pump 6 can be discharged to the tank 22 via the control valve 59. . Further, when the control valve 59 is switched to the communication position (left and right (I) position or (III) position), the discharge pressure oil from the hydraulic pump 6 is selectively output to the oil passages 26a and 26b. The actuator 10 can be operated as desired. Further, a check valve 53 is disposed between the discharge oil passage 25 and the control valve 59 in order to prevent the pressure oil from flowing back from the oil passages 26a, 26b to the discharge oil passage 25.

  The hydraulic circuit 51 is provided with a switching valve 52 that connects and disconnects the tank port of the control valve 59 and the tank 22. The switching valve 52 is controlled by the electromagnetic control valve 14 that outputs the pressure oil supplied from the original pressure supply source 19b as a pilot pressure, and can be switched between a communication position and a cutoff position. A throttle 32 is disposed downstream of the switching valve 52, and a pilot oil passage 58 connected to the pump control device 8 is connected between the throttle 32 and the switching valve 52.

  When the control valve 59 is operated in the direction from the neutral position (II) to the (I) position or the (III) position with the switching valve 52 switched to the communication position, the control valve 59 passes through the center bypass circuit of the control valve 59. The flow rate is gradually reduced, and the pressure on the upstream side of the throttle 32 is also gradually reduced. The pressure on the upstream side of the throttle 32 acts as a pressure for controlling the pump control device 8 via the pilot oil passage 58.

  The pump control device 8 controls to increase the pump capacity of the hydraulic pump 6 in a manner that is inversely proportional to the decrease in pressure upstream of the throttle 32. When the control valve 59 is completely switched to the (I) position or the (III) position, the center bypass circuit is blocked, so that the pressure upstream of the throttle 30 is the same level as the tank 22. . At this time, the hydraulic pump 6 has a maximum pump capacity under the control of the pump control device 8.

  Further, by switching the switching valve 52 to the cutoff position, the pressure in the pilot oil passage 58 can be set to the same level as that of the tank 22, so that the hydraulic pump 6 can be set to the maximum pump capacity.

  Such a control flow in the hydraulic circuit 51 is also basically configured as the control flow of the control flow of the first embodiment shown in FIG. For this reason, the control flow of the third embodiment will be described with reference to the control flow of the first embodiment shown in FIG. 2, focusing on the configuration of the portion different from the control flow in the first embodiment.

  In step 2, when the auto-decel control is started, the charge valve 15 is in a shut-off state, the control valve 59 is maintained in the neutral position (II), and the switching valve 52 is in the connection position. When it is determined in step 3 that the accumulator pressure is equal to or higher than the pressure P1, as in the case of the first embodiment, the automatic deceleration control in which the automatic deceleration speed is set to a low speed (for example, 1000 rpm) in step 4. Is done.

  At this time, the control valve 59 shown in FIG. 4 is held in the neutral position (II position), and the pressure oil discharged from the hydraulic pump 6 is transmitted to the control valve 59, the switching valve 52 in communication, the pilot oil It is supplied to the pump control device 8 via the path 58. The pump capacity of the hydraulic pump 6 is controlled to the minimum pump capacity in a manner that is inversely proportional to the magnitude of the pressure in the pilot oil passage 58.

  In step 6, when the auto-decel control state is canceled, the charge valve 15 is switched to the connection position. Thus, the pressure oil discharged from the accumulator 16 can be used as pressure oil for reinforcing the pressure in the discharge oil passage 25. At this time, since the switching valve 52 is held at the communication position, the pressure in the pilot oil passage 58 decreases from the state of the discharge pressure from the hydraulic pump 6 to the same level as the tank 22. As a result, the hydraulic pump 6 increases from the minimum pump capacity to the maximum pump capacity in conjunction with the operation of the control valve 59 from the neutral position (II position) to the (I) position or (III) position. Will go.

  In step 8, the charge valve 15 is switched to the cutoff position. When the control valve 59 is completely switched to the (I) position or the (III) position, the center bypass circuit of the control valve 59 is closed, so that the hydraulic pump 6 can be maintained at the maximum pump capacity.

  On the other hand, if it is determined in step 3 that the accumulator pressure is smaller than the pressure P1, the process proceeds to step 10 where auto-decel control is performed with the auto-decel rotation speed set to a medium speed (for example, 1400 rpm). At this time, the charge valve 15 is in a cutoff state, and the switching valve 52 is in a connected state.

  As a result, the discharge pressure of the hydraulic pump 6 acts on the pump control device 8, and the hydraulic pump 6 is in a minimum pump capacity state. At the same time, since the pressure oil flow rate in the discharge oil passage 25 can be discharged to the tank via the throttle 32, an increase in pressure in the discharge oil passage 25 can be suppressed.

In step 11, when the operation of the operation lever 11a is confirmed and the process proceeds to step 12, the charge valve 15 is held in the cutoff position, and the switching valve 52 is held in the communication position.
When the operation of the operation lever 11a is not confirmed in step 11 and the process proceeds to step 13 to accumulate pressure in the accumulator 16, the charge valve 15 is switched to the connection position. As a result, the pressure oil discharged from the hydraulic pump 6 can be accumulated in the accumulator 16.

  At this time, by controlling the switching valve 52 to the shut-off position, the pressure of the discharge circuit 25 can be increased, and the pump capacity of the hydraulic pump 6 can be increased from the minimum pump capacity. Accumulation of pressure can be performed quickly.

Thereafter, when the pressure accumulation in the accumulator 16 is stopped in step 15, the charge valve 15 is switched to the cutoff position. At this time, since the switching valve 52 is switched to the cutoff position, the switching valve 52 is returned to the communication position. As a result, the pressure oil flow rate in the discharge oil passage 25 can be discharged to the tank via the throttle 32, so that an increase in pressure in the discharge oil passage 25 can be suppressed. Further, since the discharge pressure of the hydraulic pump 6 can be applied to the pump control device 8, the pump capacity of the hydraulic pump 6 can be returned to the minimum pump capacity.
After the charge valve 15 is switched to the cutoff position, the engine speed is reset to the auto-decel speed on the low speed side.

  In step 17, when the accumulator 16 is stopped from accumulating and the operation is resumed from the auto-decel control state, the charge valve 15 is switched to the shut-off position, and the switching valve 52 is held at the communication position. At this time, the engine increases from the auto-decel rotation speed on the middle rotation side.

  Moreover, since the control valve 59 is switched to the communication position (I) or (III), the actuator 10 can be smoothly operated by the pressure oil discharged from the hydraulic pump 6. At this time, the pump capacity of the hydraulic pump 6 may increase from the minimum pump capacity to the maximum pump capacity in a manner that is inversely proportional to the pressure in the pilot oil passage 58 decreasing from the discharge pressure of the hydraulic pump 6. it can.

  As described above, also in the third embodiment, according to the pressure accumulated in the accumulator 16, the auto-decel rotation speed can be selected and set from two types of the low rotation side and the medium rotation side. Therefore, the same effect as that described in the first embodiment can be obtained.

  Next, a control device and a control method according to Embodiment 4 of the present invention will be described with reference to FIG. As shown in FIG. 5, in the hydraulic circuit 71 in the fourth embodiment, the hydraulic circuit 51 in the third embodiment has a basic circuit configuration, and instead of the charge valve 15 disposed in the hydraulic circuit 51, the hydraulic circuit 51 in the second embodiment is used. The circuit configuration in which the pressure oil accumulated in the accumulator 16 is directly discharged to the actuator 10 is employed.

  In this configuration, the configuration according to the fourth embodiment is different from the configurations of the second and third embodiments including the configuration in the first embodiment. Other configurations are the same as those in the first to third embodiments. For this reason, about the member which has the structure similar to the structure in Example 1- Example 3, suppose that description of the member is abbreviate | omitted by expressing using the same code | symbol.

In the hydraulic circuit 71 according to the fourth embodiment, as with the hydraulic circuit 51 according to the third embodiment, the control valve 59 is configured as an open center type directional switching valve that can be switched to the 6-port 3 position.
A switching valve 52 that is controlled by the pilot pressure output from the electromagnetic control valve 14 is disposed between the control valve 59 and the tank 22.

  In the hydraulic circuit 71, a charge valve 45 that can be switched to the 4-port 3-position as in the second embodiment is disposed between the discharge oil passage 25 and the accumulator 16. Further, electromagnetic control valves 48 a and 48 b that output pilot pressure for controlling connection / disconnection of the charge valve 45 are controlled by a controller 67.

  Since it is configured in this way, the control flow of the hydraulic circuit 71 in the fourth embodiment is also basically configured as the control flow of the control flow of the first embodiment shown in FIG. For this reason, focusing on the control flow described in the first embodiment, the operation of characteristic members in the second and third embodiments is the control flow in the second and third embodiments. A control flow will be performed.

  Under the control of the controller 67, the hydraulic circuit 71 can be controlled according to the control flow of the first embodiment shown in FIG. 2 and the control flow of the second and third embodiments described above. Further, depending on the magnitude of the pressure accumulated in the accumulator 16, the auto-decelerating speed of the engine 2 can be selected and set from two types of low speed and medium speed.

  Thereby, the effect similar to the effect shown in Example 1 mentioned above can be show | played also in Example 4. FIG. Moreover, the same effects as those obtained in the second and third embodiments described above can also be achieved in the fourth embodiment.

It is a hydraulic circuit diagram. (Example 1) It is the flowchart which showed the control flow. (Examples 1-4) It is another hydraulic circuit diagram. (Example 2) It is another hydraulic circuit diagram. (Example 3) It is another hydraulic circuit diagram. Example 4 It is a block diagram which performs opening / closing control of a charge valve. (Example)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hydraulic circuit, 2 ... Engine, 6 ... Variable displacement hydraulic pump, 7 ... Controller, 8 ... Pump control apparatus, 9 ... Control valve, 10 ... Actuator, DESCRIPTION OF SYMBOLS 12 ... Unload valve, 13 ... Unload cancellation piston, 15 ... Charge valve, 16 ... Accumulator, 25 ... Discharge oil path, 41, 51, 71 ... Hydraulic circuit, 45 ... Charge valve, 47, 57, 67 ... Controller, 52 ... Switching valve, 59 ... Control valve.

Claims (9)

At least one variable displacement hydraulic pump driven by an engine;
At least one hydraulic actuator driven by pressure oil discharged from the variable displacement hydraulic pump;
A control valve for controlling the pressure oil discharged from the variable displacement hydraulic pump to supply and discharge the hydraulic actuator;
An operating lever for operating the control valve;
A control device having an auto-decel control function for the engine,
An accumulator that discharges reinforcing pressure oil to the discharge pressure oil from the variable displacement hydraulic pump;
A charge valve for connecting and disconnecting the pressure oil discharged from the accumulator,
The control device is configured to control the charge valve to be in a communicating state when releasing the auto-decel control and increasing the engine speed by operating the operation lever during auto-decel control. Control device with auto-decel control function. A rotation speed setting unit that selects from two types of rotation speed and sets the auto-decel rotation speed is provided.
When the auto-decel control is canceled and the engine speed is increased from the low-speed side auto-decel speed set by the speed setting unit, the charge valve is in a communication state and is set by the speed setting unit. 2. The auto-decel control function according to claim 1, wherein when the auto-decel control is canceled and the engine speed is increased from the other auto-decel speed other than the low-speed side, the charge valve is shut off. Control device with.   3. The auto-decel according to claim 2, wherein the rotation speed setting unit sets the auto-decel rotation speed by selecting from the two kinds of rotation speeds according to the pressure accumulated in the accumulator. A control device with a control function. An unload valve for controlling connection / disconnection of the discharge of the pressure oil discharged from the variable displacement hydraulic pump to the tank;
A cancel mechanism for maintaining the unload valve in a shut-off state;
With
The unload valve is controlled according to a differential pressure between a load pressure of the actuator and a discharge pressure from the variable displacement hydraulic pump, and is maintained in a shut-off state by the cancel mechanism. The control apparatus provided with the auto-decel control function in any one of Claims 1-3.   The control valve is an open center type control valve having a center bypass circuit, and a switching valve for connecting and disconnecting the center bypass circuit and the tank is disposed between the center bypass circuit and the tank. The control apparatus provided with the auto-decel control function according to any one of claims 1 to 3. At least one variable displacement hydraulic pump driven by an engine;
At least one hydraulic actuator driven by pressure oil discharged from the variable displacement hydraulic pump;
A control valve for controlling the pressure oil discharged from the variable displacement hydraulic pump to supply and discharge the hydraulic actuator;
An operating lever for operating the control valve;
A control method of auto-decel control for the engine using a control device comprising:
Canceling the auto-decel control and increasing the engine speed by operating the operation lever during auto-decel control;
A control method for auto-decel control, characterized in that, when the engine speed is increased by releasing auto-decel control, the pressure oil accumulated in the accumulator is discharged to the discharge pressure oil from the variable displacement hydraulic pump. . Select from two types of rotation speed and set auto-decel rotation speed,
When releasing the auto-decel control and increasing the engine speed from the low-speed side auto-decel speed, which is one of the speeds, the pressure oil accumulated in the accumulator is discharged from the variable displacement hydraulic pump. Discharging into the
When releasing the auto-decel control and increasing the engine speed from the other auto-decel speed that is not on the low-speed side, the pressure oil accumulated in the accumulator is discharged to the discharge pressure oil from the variable displacement hydraulic pump 7. The auto-decel control method according to claim 6, wherein the control is prohibited.   8. The control method for auto-decel control according to claim 7, wherein the auto-decel rotation speed is set by selecting from the two types of rotation speeds according to the pressure accumulated in the accumulator.   9. The auto-decel control, wherein when the pressure accumulated in the accumulator is equal to or lower than a predetermined pressure, the discharge pressure oil from the variable displacement hydraulic pump is used for accumulating the accumulator. A control method for auto-decel control according to any one of the above.

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