JP2011002073A - Hydraulic device for working machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively use pressure oil by supplying control flow to a rolling control valve side, and sending whole quantity of pressure oil at an upstream side of a flow distributing valve to a lift control valve side at the time of neutral position operation during which rolling control is not executed.SOLUTION: This device includes: a flow distributing valve 38 capable of distributing and supplying pressure oil to the lift control valve 42 and the rolling control valve 39; and a control means 14A controlling the flow distributing valve 38 so as to supply control flow to the rolling cylinder 11 side and to supply surplus flow to the lift cylinder 9 side when the rolling control valve 39 is operated to a position at which pressure oil is supplied to the rolling cylinder 11 side, and controlling the flow distributing valve 38 so as to supply whole quantity of pressure oil at the upstream side to the lift control valve 42 side when the rolling control valve 39 is operated to the neutral position at which supply of pressure oil to the rolling cylinder 11 side is stopped.

Description

  The present invention is such that the working device supported by the lift arm attached to the traveling machine body is configured to be driven up and down by an elevating cylinder and is supported so as to be able to roll around the longitudinal axis with respect to the traveling machine body. The present invention relates to a hydraulic device for a working machine configured to be capable of rolling control with a rolling cylinder.

As a hydraulic device for this type of work machine, a structure described in [1] or [2] below is conventionally known.
[1] The discharge oil from the pump is configured to be able to be distributed and supplied to the pressure oil supply path to the lifting cylinder and the pressure oil supply path to the rolling cylinder. A flow priority valve provided at a branch point to the supply path is configured to supply a control flow to the rolling cylinder side and supply an excess flow to the lifting cylinder side (see, for example, Patent Document 1).
[2] The discharge oil from the pump is configured to be able to be distributed and supplied to the pressure oil supply path to the lifting cylinder and the pressure oil supply path to the rolling cylinder. Performed by a diversion valve provided at the branch point to the supply path, supplying control flow to the rolling cylinder side, supplying surplus flow to the lifting cylinder side, and changing the flow rate of control flow to the rolling cylinder side One having a control flow changing means capable (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 2000-92911 (paragraph numbers 0048 and 0049, FIG. 3) JP-A-11-280704 (paragraph numbers 0027 and 0030, FIG. 3)

In the conventional structure shown in [1] above, the discharge oil from the pump is distributed and supplied to the pressure oil supply path to the lifting cylinder and the pressure oil supply path to the rolling cylinder via the flow priority valve. Since it is configured to be possible, pump discharge oil can always be supplied to both the pressure oil supply path to the lifting cylinder and the pressure oil supply path to the rolling cylinder. In particular, the control flow is supplied to the rolling cylinder side instead of the pressure oil whose flow rate fluctuates greatly like the surplus flow. Therefore, the necessary flow rate is always supplied to the rolling cylinder side, which is frequently used. It can be used conveniently when pressure oil can be secured and the lifting cylinder is in use, without causing a problem that the rolling operation cannot be performed satisfactorily due to insufficient oil supply to the rolling cylinder. It is useful in that it can.
However, in the conventional structure, the amount of oil supplied as a control flow to the pressure oil supply path side to the rolling cylinder cannot be supplied to the lifting cylinder side. In order to secure a large amount of oil, it was necessary to increase the pump capacity itself.

In the prior art described in [2] above, the control flow is supplied to the rolling cylinder side by the diversion valve provided at the branch point from the pump to the both-pressure oil supply circuit, and the surplus flow is supplied to the lifting cylinder side. Since it is provided with control flow changing means that can change the flow rate of the control flow to the rolling cylinder side, the flow rate of the surplus flow when the control flow rate is reduced is increased to some extent. It is possible.
However, even the structure configured as described above cannot supply all of the unused control flow to the lifting cylinder side, and there is room for improvement in this respect.

  An object of the present invention is to supply pressure oil by a control flow to the rolling control valve side so that the rolling control is performed while maintaining the state where the rolling control is always performed accurately regardless of the operation state on the lifting control valve side. When the neutral position operation of the rolling control valve is not performed, the entire amount of the pressure oil upstream of the flow distribution valve can be sent to the lift control valve side so that the pressure oil can be effectively used.

[Solution 1]
The technical means of the present invention taken in order to solve the above-mentioned problem is configured such that the working device connected to the traveling machine body can be driven up and down by the lifting cylinder and the working device can be controlled by the rolling cylinder. In a working machine hydraulic device,
The pressure oil supply path to the lifting cylinder is provided with a lift control valve, the pressure oil supply path to the rolling cylinder is provided with a rolling control valve,
A flow rate distribution valve capable of distributing and supplying pressure oil to both the elevation control valve and the rolling control valve;
When the rolling control valve is operated to a rolling operation position for supplying pressure oil to the rolling cylinder side, the control flow is supplied to the rolling cylinder side, and the flow rate is set so that the surplus flow is supplied to the lifting cylinder side. When the distribution valve is controlled and the rolling control valve is operated to a neutral position where the supply of pressure oil to the rolling cylinder side is stopped, the entire amount of upstream pressure oil is supplied to the lift control valve side. And a control means for controlling the operation of the flow rate distribution valve.

[Action and effect]
As described above, in the hydraulic device for a working machine according to the present invention according to the solution 1, the pressure oil supply path to the lifting cylinder is provided with the lifting control valve, and the rolling control valve is provided in the pressure oil supply path to the rolling cylinder. A rolling supply position for supplying pressure oil only to the rolling control valve side, a distribution supply position capable of distributing and supplying pressure oil to both the lifting control valve and the rolling control valve, and only to the lifting control valve side A flow rate distribution valve for controlling the pressure oil supply mode is provided at the elevation supply position for supplying the pressure oil.
In this way, by providing a flow distribution valve that controls the supply form of pressure oil, the control flow is supplied to the rolling cylinder side, so that the pressure of the flow rate that is always necessary to the rolling cylinder side that is frequently used is maintained. Securing of rolling control can be avoided by securing oil and avoiding the problem that rolling operation cannot be performed satisfactorily because the amount of oil supplied to the rolling cylinder is insufficient when the lifting cylinder is used. Can be planned.

Further, in the hydraulic device for a working machine of the present invention according to the above solution 1, when the rolling control valve is operated to the neutral position where the pressure oil supply to the rolling cylinder side is stopped, the total amount of upstream pressure oil The flow rate distribution valve is configured so as to be supplied to the lift control valve side.
As a result, the amount of oil supplied to the rolling cylinder side as a control flow can be supplied to the lifting cylinder side, and more oil can be secured on the lifting cylinder side. . Therefore, there is an advantage that the lifting cylinder can be operated with good operability without having to increase the pump capacity itself.

  In addition, the flow rate distribution valve itself capable of controlling the pressure oil supply mode and the control means for controlling the operation of the flow rate distribution valve are provided to the lifting control valve side when the pressure oil supply to the rolling cylinder side is stopped. Since the entire amount can be supplied, there is an advantage that the structure for supplying the entire amount can be easily configured without adding a special structure.

[Solution 2]
The technical means of the present invention taken in order to solve the above-mentioned problems is characterized in that the rolling control valve is constituted by an electromagnetic proportional control valve, and can be operated manually by operation of a manual operation switch.

[Action and effect]
As described above, in the hydraulic device of the working machine according to the present invention according to Solution 2, the electromagnetic proportional control valve for performing the rolling control is configured to be manually operable by operating the manual operation switch. Apart from the rolling control during normal work, there is an advantage that various ways of use are possible, such as temporarily changing the attitude of the machine body by human operation and attaching or removing various work devices.

[Solution 3]
The technical means of the present invention taken in order to solve the above problem is that the control current for operating the rolling control valve in accordance with the turning-on operation by the manual operation switch gradually increases from the current at the time of the turning-on operation by the manual operation switch. It is comprised as follows.

[Action and effect]
As described above, in the hydraulic device of the working machine according to the present invention according to the solving means 3, the control current for operating the rolling control valve in accordance with the turning operation by the manual operation switch is determined from the current at the time of the turning operation by the manual operation switch. Since it is gradually increased, it can be conveniently used when a gentle inching operation is performed while the switch operation is simply on / off.

Overall right side view of the tractor Rear right side view of the rear of the tractor Block diagram showing tractor control system Hydraulic circuit diagram showing the configuration of the hydraulic mechanism for lifting and rolling Hydraulic circuit diagram showing operation of flow distribution valve Hydraulic circuit diagram showing operation of flow distribution valve Time chart showing operation of control system

  Hereinafter, an embodiment in which a hydraulic device for a working machine according to the present invention is applied to a tractor as an example of a working machine will be described with reference to the drawings.

〔overall structure〕
FIG. 1 is an overall right side view of the tractor. As shown in this figure, the tractor has an engine 1 mounted on the front thereof. The engine 1 is connected to a transmission case 2 that also serves as a frame so as to extend from the rear portion of the engine 1 toward the rear of the vehicle body. A pair of left and right front wheels 3 are disposed on both left and right sides of the engine 1 so as to be steerable and drivable. On the left and right sides of the rear portion of the transmission case 2, a pair of left and right rear wheels 4 are arranged to be drivable and brakeable. Above the mission case 2, a steering wheel 5 for driving the front wheels, a driver's seat 6, and the like are provided to form a boarding driver 7.

  FIG. 2 is a vertical right side view of the rear portion of the tractor, and FIG. 3 is a diagram showing a lift control structure and a rolling control structure of the tractor. As shown in FIGS. 1 to 3, a pair of left and right lift arms that enable the lifting and lowering operation of a working device (not shown) such as a rotary tiller and a plow connected to the rear portion of the tractor are provided at the rear portion of the mission case 2. 8 and a pair of left and right lifting cylinders 9 that swing and drive the corresponding lift arm 8 in the vertical direction are provided.

  The right lift arm 8 is connected via a rolling cylinder 11 to a right lower link 10 which is connected to the lower right portion of the rear end of the transmission case 2 so as to be swingable up and down. The left lift arm 8 is connected via a connecting rod 12 to a left lower link 10 that is connected to the lower left portion of the rear end of the transmission case 2 so as to be able to swing up and down. A single-acting hydraulic cylinder is adopted for the left and right lifting cylinders 9, and a double-acting hydraulic cylinder is adopted for the rolling cylinder 11.

  That is, this tractor can drive the working device up and down by switching the flow of hydraulic oil to the left and right lifting cylinders 9 and operating the left and right lifting cylinders 9 to extend and contract. Further, the working device can be driven to roll by switching the flow of hydraulic oil to the rolling cylinder 11 and extending and contracting the rolling cylinder 11.

  The flow of hydraulic oil to the left and right lifting cylinders 9 and the rolling cylinder 11 is switched by the operation of the lifting / rolling hydraulic mechanism 13. The operation of the hydraulic mechanism 13 is controlled by the control device 14.

[Elevation / Rolling control]
The control device 14 for controlling the operation of the lifting / rolling hydraulic mechanism 13 is configured as follows.
The control device 14 is configured using a microcomputer, and includes control means 14A having a control command to be output to the hydraulic mechanism 13 based on various input signals as a control program; And storage means 14B for storing data for rolling control.

First, the elevation control relationship will be described.
The operating device connected to the rear part of the tractor is operated by operating the first elevating lever 15 which is disposed so as to be able to hold the position at the right side of the driver's seat 6 in the boarding operation unit 7 (see FIG. 1). The first elevating lever 15 can be positioned at a height corresponding to the operation position.
That is, the control means 14A outputs the output of the first lever sensor 16 that detects the operation position of the first lifting lever 15 for lifting the working device, the output of the arm sensor 17 that detects the swing angle of the lift arm 8, and The operation of the hydraulic mechanism 13 is controlled so that the swing angle of the lift arm 8 corresponds to the operating position of the first lifting lever 15 based on the correlation data for lifting that corresponds to the output of.

  The first lever sensor 16 and the arm sensor 17 are composed of a rotary potentiometer. The correlation data for raising and lowering is stored in the nonvolatile storage means 14B composed of an EEPROM or the like provided in the control device 14 as data for raising and lowering control. Note that map data set in advance as the output on the arm sensor 17 side corresponding to the output on the first lever sensor 16 side can be adopted as the correlation data for raising and lowering.

  When the control means 14A detects an upward operation of the second lift lever 18 based on the output of the second lever sensor 19 that detects the operation of the second lift lever 18 for lifting the work device, the work device On the basis of the output of the upper limit setter 20 for setting the upper limit position and the output of the arm sensor 17, the hydraulic mechanism 13 is operated so that the swing angle of the lift arm 8 corresponds to the set upper limit position of the work device. Control.

On the other hand, when the downward operation of the second lift lever 18 is detected, the lift arm 8 is based on the output of the first lever sensor 16, the output of the arm sensor 17, and the correlation data for lift. The operation of the hydraulic mechanism 13 is controlled so that the swing angle corresponds to the operating position of the first elevating lever 15.
That is, by operating the second elevating lever 18, the height position of the working device connected to the rear portion of the tractor is set by the upper limit position of the working device set by the upper limit setting device 20 and the first elevating lever 15. It is possible to switch to the height position of the working device.

  In addition, the 2nd raising / lowering lever 18 is a neutral return type | mold, and is arrange | positioned in the lower right position of the steering wheel 5 in the boarding operation part 7 (refer FIG. 1). The second lever sensor 19 includes a normally-open first contact that is closed in conjunction with an upward swing operation of the second lift lever 18 and a downward swing operation of the second lift lever 18. It is possible to employ a switch configured by using a switch having a normally open second contact that is closed in conjunction with the switch. The upper limit setter 20 is arranged at a position on the right side of the driver's seat 6 in the boarding driver 7. The upper limit setter 20 is composed of a rotary potentiometer.

  When the control unit 14A detects the grounding of the working device based on the output of a working depth sensor (not shown) provided in the working device so as to detect the working depth of the working device when the working device is lowered. The working depth of the working device corresponds to the set working depth based on the output of the working depth sensor and the output of the working depth setting device 21 for setting the working depth of the working device. The operation of the hydraulic mechanism 13 is controlled.

  That is, when a grounding type work device such as a rotary tiller equipped with a work depth sensor is connected to the rear portion of the tractor, the work depth of the work device is set by the work depth setting device 21. The working depth can be maintained.

  The work depth setting device 21 is provided at a position on the right side of the driver's seat 6 in the boarding driver 7. As the working depth setting device 21, a rotary potentiometer or the like can be adopted. As the working depth sensor, a sensor configured using a rotary potentiometer, a sensor configured using an ultrasonic sensor, or the like can be used.

Next, the rolling control relationship will be described.
This tractor is equipped with an angle sensor 22 for detecting the rolling angle of the tractor body and an angular velocity sensor 23 for detecting the rolling angular speed of the tractor body.

The control unit 14A calculates the actual rolling angle of the tractor based on the output of the angle sensor 22 and the output of the angular velocity sensor 23. Also, the calculated correlation value, the output of the angle setting unit 24 for setting the rolling target angle of the working device, the correlation data for rolling corresponding to the rolling angle of the working device with respect to the tractor and the length of the rolling cylinder 11 Based on the above, the target length of the rolling cylinder 11 is set.
Then, based on the set value and the output of the stroke sensor 25 that detects the length of the rolling cylinder 11, the operation of the hydraulic mechanism 13 is controlled so that the output of the stroke sensor 25 corresponds to the set value. Thereby, the working device can be maintained at the target rolling angle set by the angle setting unit 24.

  A heavy water type angle sensor or the like can be adopted as the angle sensor 22 for detecting the rolling angle. As the angular velocity sensor 23 for detecting the rolling angular velocity, a vibration type gyro sensor or the like can be employed. The angle setting device 24 is arranged at a position on the right side of the driver's seat 6 in the boarding driver 7. As the angle setting device 24, a rotary potentiometer or the like can be used. As the stroke sensor 25 for detecting the length of the rolling cylinder 11, a sliding potentiometer or the like can be employed.

  Further, the correlation data for rolling is stored in the nonvolatile storage means 14B composed of EEPROM or the like provided in the control device 14 as data for rolling control. The correlation data for rolling includes map data set in advance as an output of the stroke sensor 25 on the side of the rolling cylinder 11 corresponding to the output of the angle setting unit 24 for setting the rolling target angle of the working device. Can be adopted.

The control means 14 </ b> A is configured to receive an operation signal from a rolling manual operation switch 60 provided so as to be operable by the boarding operation unit 7.
This rolling manual operation switch 60 is provided with a push button type raising operation switch 61 and a push button type lowering operation switch 62 that can be individually operated, and while the raising operation switch 61 is being pushed. Only when the raising operation command is input to the control means 14A and the pushing operation is released, the input of the raising operation command to the control means 14A is also lost. Similarly, a lowering operation command is input to the control unit 14A only while the lowering operation switch 62 is being pressed, and when the pressing operation is released, the input of the lowering operation command to the control unit 14A is lost.
The control means 14A outputs an operation signal for the electromagnetic proportional valve 39 so that the rolling cylinder 11 is contracted by pushing the raising operation switch 61 and the working device is raised, and rolling is performed by pushing the lowering operation switch 62. An operation signal for the electromagnetic proportional valve 39 is output from the control means 14A so as to extend the working cylinder 11 and lower the working device.

  The operation command of the rolling manual operation switch 60 is output as an operation signal for the electromagnetic proportional valve 39 from the control means 14A in preference to the operation commands by the angle sensor 22, the angular velocity sensor 23, and the angle setting device 24, When the operation command for the rolling manual operation switch 60 is not output, the control means 14A performs an operation for rolling control on the electromagnetic proportional valve 39 based on the operation commands from the angle sensor 22, the angular velocity sensor 23, and the angle setter 24. The state is switched to a signal output state.

In the control means 14A to which the operation command for the rolling manual operation switch 60 is inputted, after the rolling manual operation switch 60 is pushed, the operation signal for rolling control output to the electromagnetic proportional valve 39 is sent to the following. So that it is controlled.
That is, as an operation signal for rolling control output to the electromagnetic proportional valve 39, an operation command with a predetermined current value is not output from the beginning, but an operation command with a small current value is first sent, To gradually reach a predetermined current value. As a result, the electromagnetic proportional valve 39 is gently operated based on an artificial operation command from the manual operation switch 60 for rolling so that the rolling cylinder 11 can be smoothly operated by an artificial inching operation. It is configured.

[Hydraulic circuit]
As shown in FIG. 4, the lifting / rolling hydraulic mechanism 13 is connected to a hydraulic pump 26 operated by power from the engine 1 via a first supply oil path 27 and a second supply oil path 28. The first valve unit 29 is combined with a second valve unit 33 connected to the first valve unit 29.

  A rolling cylinder 11 is connected to the first valve unit 29 via a pair of first supply / discharge oil passages 30 and a pair of second supply / discharge oil passages 31, and via a third supply oil passage 32. A second valve unit 33 is connected. Left and right lifting cylinders 9 are connected to the second valve unit 33 via a third supply / discharge oil passage 34 and a pair of left and right fourth supply / discharge oil passages 35. A relief valve 36 is connected to the second supply oil passage 28. An oil filter 37 is interposed in each of the second supply oil passage 28, the pair of first supply / discharge oil passages 30, the third supply oil passage 32, and the third supply / discharge oil passage 34.

  The first valve unit 29 includes a pilot-operated flow dividing valve (an example of a flow distribution valve) 38 that divides the hydraulic oil from the hydraulic pump 26 for raising and lowering and for rolling, and an electromagnetic proportional valve for rolling (of the rolling control valve). An example) 39, the sequence valve 40, and the high pressure selection valve 53 are configured in an integral structure in which their valve bodies are integrally formed. A pair of first discharge oil passages 41 are connected to the electromagnetic proportional valve 39.

  The second valve unit 33 is connected to a pilot-operated ascending proportional valve 42, a pilot pressure-adjusting pilot valve 43 for adjusting the pilot pressure with respect to the ascending proportional valve 42, a pilot-operating descending proportional valve 44, and a descending proportional valve 44. A monoblock-type elevating proportional valve (elevating control valve) is constructed by incorporating a pilot valve 45 for lowering pilot pressure, a shuttle valve 46 for adjusting pilot pressure, and an unloading valve 47 into a common valve body 48A. An example) 48, and a check valve 49 and a throttle valve 50, which are integrally formed with the valve body 48A of the proportional valve 48 for raising and lowering. That is, the valve body 49A of the check valve 49 and the valve body 50A of the throttle valve 50 are formed integrally with the valve body 48A of the lift proportional valve 48. A second discharge oil passage 51 is connected to the lowering proportional valve 44, and a third discharge oil passage 52 is connected to the unload valve 47.

  The check valve 49 allows the hydraulic oil to flow from the rising proportional valve 42 to the left and right lifting cylinders 9 and prevents the hydraulic oil from flowing from the left and right lifting cylinders 9 to the rising proportional valve 42. The throttle valve 50 is configured to adjust the lowering speed of the left and right lift arms 8 (working device) by restricting the flow rate of the hydraulic oil flowing from the left and right lifting cylinders 9 toward the lowering proportional valve 44. It is configured.

  Based on the operation of the electromagnetic proportional valve 39 for rolling, the diversion valve 38 reduces the total oil amount to the second valve when the electromagnetic proportional valve 39 prevents supply and discharge of hydraulic oil to and from the rolling cylinder 11. When the electromagnetic proportional valve 39 allows the hydraulic oil to be supplied / discharged to / from the rolling cylinder 11 by supplying to the unit 33, the limit flow rate for the rolling cylinder 11 set in advance is set as the upper limit, and the rolling cylinder 11 An oil amount necessary for the operation is supplied to the rolling cylinder 11 via the electromagnetic proportional valve 39, and the remaining oil amount is supplied to the second valve unit 33.

  That is, the diversion valve 38 supplies the upstream hydraulic oil supplied from the hydraulic pump 26 to the supply circuit side to the rolling cylinder 11 with the preset limit flow rate as the upper limit, Among the total amount of oil discharged from the rolling supply position 38a and the hydraulic pump 26 where no hydraulic oil is supplied, the upper limit is set to the limit flow rate to the supply circuit side to the rolling cylinder 11, and the elevating cylinder 9 All the remaining amount is distributed to the supply circuit side to supply to the distribution supply position 38c where it can be supplied together, and supplied to the supply circuit side to the lifting cylinder 9 and hydraulic oil is supplied to the rolling cylinder 11 side. And an elevating / lowering supply position 38b that does not supply.

The pilot pressure derived from the flow path upstream of the electromagnetic proportional valve 39 on the downstream side in the hydraulic oil supply direction with respect to the flow dividing valve 38 is applied to the lift supply position 38b side of the flow dividing valve 38. A first pilot passage PL1 is provided.
Further, a second pilot passage PL2 is provided on the side of the rolling supply position 38a of the diversion valve 38 so that the load pressure of the rolling cylinder 11 is applied. That is, the first valve unit 29 is provided with third pilot passages PL2u, PL2d for guiding the load pressure of the rolling cylinder 11, and a high pressure selection valve 53 for selecting the high pressure side of the third pilot passages PL2u, PL2d. The second pilot passage PL2 is connected to the third pilot passages PL2u and PL2d so that the pilot pressure selected at the high pressure acts on the side of the rolling supply position 38a of the flow dividing valve 38.
Further, on the rolling supply position 38a side of the diversion valve 38, an urging spring 38d that presses and urges the diversion valve 38 from the rolling supply position 38a side to the lift supply position 38b side is provided.

  The electromagnetic proportional valve 39 supplies hydraulic oil to the ascending side chamber 11u of the rolling cylinder 11, and the ascending side position 39u for guiding the return oil from the descending side chamber 11d of the rolling cylinder 11 to the oil tank T, and the rolling The hydraulic oil is supplied to the descending side chamber 11d of the cylinder 11 to supply and discharge the pressure oil to the descending side position 39d for guiding the return oil from the ascending side chamber 11u of the rolling cylinder 11 to the oil tank T and the rolling cylinder 11. And a neutral position 39c to be stopped, and can be switched by an operation signal from the control means 14A of the control device 14.

[Control action in hydraulic circuit]
When the electromagnetic proportional valve 39 is operated to the ascending position 39u or the descending position 39d, the load pressure of the rolling cylinder 11 is transmitted to the third pilot passages PL2u, PL2d, and the high pressure selection valve 53, the second pilot. It acts on the rolling supply position 38a side of the flow dividing valve 38 through the passage PL2.
Further, the urging force of the urging spring 38d that presses and urges the diversion valve 38 from the rolling supply position 38a side to the lift supply position 38b side acts on the rolling supply position 38a side of the diversion valve 38.
For this reason, the diversion valve 38 is such that the sum of the urging force of the urging spring 38d and the oil pressure due to the load pressure is balanced with the oil pressure due to the upstream pressure of the electromagnetic proportional valve 39 acting on the lift supply position 38b side. In addition, the amount of throttling at the distribution supply position 38c provided in the middle portion of the flow dividing valve 38 is adjustable. (See FIG. 5 (a) and FIG. 5 (b))

That is, during the rolling control in the steady state where the electromagnetic proportional valve 39 is operated to the ascending side position 39u or the descending side position 39d to supply and discharge the pressure oil to and from the rolling cylinder 11, FIG. As shown, the diversion valve 38 is in the distribution supply position 38c, and the sum of the urging force of the urging spring 38d and the oil pressure due to the load pressure of the rolling cylinder 11 acts on the lift supply position 38b side. Control is performed so that the oil pressure due to the upstream pressure of the proportional valve 39 is balanced.
When the rolling cylinder 11 reaches the stroke end and the load pressure suddenly increases, or when the load pressure acting on the rolling cylinder 11 suddenly increases due to unevenness of the traveling road surface or the like, FIG. As shown in b), the diversion valve 38 may be transiently operated to the rolling supply position 38a side.
If the sudden increase in the load pressure can be eliminated naturally, such as unevenness on the road surface, the control is performed so that the load distribution fluctuation is eliminated and the original distribution supply position 38c is returned. Further, if the load pressure is generated by reaching the stroke end, the electromagnetic proportional valve 39 is operated to the neutral position 39c as shown in FIGS. 6A and 6B in accordance with the detection of the stroke end. Accordingly, the flow dividing valve 38 is also operated to the distribution supply position 38c as described later.
The rolling supply position 38a appears as a result of the urging force of the urging spring 38d acting even in the initial state where the engine 1 is not started as shown in FIG. As soon as the pressure oil from the pump 26 is supplied, it is operated to the distribution supply position 38c.

When the electromagnetic proportional valve 39 is operated to a neutral position 39c where supply / discharge of pressure oil to / from the rolling cylinder 11 is stopped, the flow dividing valve 38 is operated as follows.
When the electromagnetic proportional valve 39 is operated to the neutral position 39c, the third pilot passages PL2u and PL2d are both in communication with the tank T, so that they act on the rolling supply position 38a side of the flow dividing valve 38 via the second pilot passage PL2. Pilot pressure disappears. As a result, in the diversion valve 38, the pilot pressure of the first pilot passage PL1 acting on the up / down supply position 38b side overcomes the urging force of the urging spring 38d on the other end side, and the diversion valve 38 is placed in the intermediate distribution supply position. It is configured to perform switching operation to the 38c side or the elevation supply position 38b side. (See FIG. 6 (a) and FIG. 6 (b))

As shown in FIG. 6A, when the diverter valve 38 is operated to the distribution supply position 38c in a state where the electromagnetic proportional valve 39 is operated to the neutral position 39c, supply and discharge of pressure oil to the rolling cylinder 11 side is performed. Therefore, the entire amount of pressure oil supplied from the hydraulic pump 26 side is supplied to the second valve unit 33 side.
Further, as shown in FIG. 6B, even when the diverter valve 38 is operated to the lifting / lowering supply position 38b side while the electromagnetic proportional valve 39 is operated to the neutral position 39c, the rolling cylinder 11 side is not moved. Since the supply and discharge of the pressure oil is stopped, the entire amount of the pressure oil supplied from the hydraulic pump 26 side is supplied to the second valve unit 33 side. However, in this state, for example, as shown in FIG. 5A or 5B, the electromagnetic proportional valve 39 is operated to the ascending side position 39u or the descending side position 39d to This phenomenon occurs transiently in a specific situation such as immediately after the electromagnetic proportional valve 39 is suddenly operated to the neutral position 39c from the state in which pressure oil is supplied and discharged. Absent. Thereafter, the diversion valve 38 is operated to the distribution supply position 38c side by the urging force of the urging spring 38d on the other end side, and finally the state shown in FIG.

The relief valve 36 provided on the upstream side in the pressure oil supply direction from the flow dividing valve 38 is used when the rolling cylinder 11 reaches the stroke end or when the electromagnetic proportional valve 39 is operated to the neutral position 39c. The relief pressure is set so that the pressure oil in the first supply oil passage 27 and the second supply oil passage 28 can be discharged to the oil tank T side when the place of hydraulic oil supplied from the hydraulic pump 26 is lost. It is.
The unload valve 47 provided in the third supply oil passage 32 of the second valve unit 33 is configured such that when the ascending proportional valve 42 is in the neutral position 42a, the spring chamber of the unload valve 47 is in the tank passage (second exhaust oil The pressure in the third supply oil passage 32 is unloaded in order to communicate with the passage 51).
When the ascending proportional valve 42 is at the ascending position 42b, the load pressure of the elevating cylinder 9 is guided to the spring chamber of the unloading valve 47, so that the pressure of the third supply oil passage 32 is changed to “Pu (third supply oil passage). 32 pressure) = Pf (load pressure of the lifting cylinder 9) + Ps (pressure against the biasing force of the spring 47c) ”.
Since the relief pressure of the relief valve 36 is set higher than the aforementioned “Pf + Ps”, when the electromagnetic proportional valve 39 is operated to the neutral position 39 c, the third supply oil passage 32 of the second valve unit 33. Regardless of whether the engine is in an on-load state or an unload state, the diversion valve 38 is controlled to the distribution supply position 38c, and the entire amount of hydraulic fluid supplied from the hydraulic pump 26 is supplied to the third supply oil passage 32 side.

When the rolling cylinder 11 reaches the stroke end, the relief operation of the relief valve 36 occurs simultaneously when the rolling cylinder 11 reaches the stroke end.
On the control means 14A side of the control device 14, when a detection signal of the stroke sensor 25 is input, a control command is not output so as to return the electromagnetic proportional valve 39 to the neutral position 39c at the same time. When it is confirmed that the stroke end detection signal from the sensor 25 has continued for a predetermined time dt (see FIG. 7), a control command for returning the electromagnetic proportional valve 39 to the neutral position 39c is output after the predetermined time dt. The program is set. The delay of the predetermined time dt is for surely recognizing that the rolling cylinder 11 has reached the stroke end.

  The flow dividing valve 38, the electromagnetic proportional valve 39, and the control means 14A of the control device 14 configured as described above operate in conjunction with each other to supply hydraulic oil from the hydraulic pump 26 to the lifting cylinder 9. The supply circuit side and the supply circuit side to the rolling cylinder 11 are distributed and supplied.

  In the control means 14A, the operation of the ascending proportional valve 42 of the second valve unit 33 is controlled as follows in relation to the recording / dividing valve 38, the electromagnetic proportional valve 39, and the relief valve 36. is doing.

That is, as shown in FIG. 7, at the time t0 when the rolling cylinder 11 reaches the stroke end, the relief valve 36 is opened and the relief operation is performed. At this time, the stroke end detection signal from the stroke sensor 25 is input to the control means 14A, but at this time t0, the control means for returning the electromagnetic proportional valve 39 to the neutral position 39c is not yet output from the control means 14A.
Then, the control means 14A, to which the detection signal from the stroke sensor 25 is inputted, is applied to the electromagnetic proportional control valve 39 from the detection signal generation time t0 at the stroke end to the time t1 after elapse of a predetermined time dt. A return operation command to the neutral position 39c is output.

When the electromagnetic proportional control valve 39 is returned to the neutral position 39c, the flow dividing valve 38 is simultaneously switched to the distribution supply position 38c.
Then, the electromagnetic proportional control valve 39 is returned to the neutral position 39c and no pressure oil is supplied to the rolling cylinder 11 side, so that the total amount of oil discharged from the hydraulic pump 26 is supplied to the pressure cylinder 9 side. It is sent to the third supply oil passage 32 of the second valve unit 33 which is a circuit. Then, the unload valve 47 provided in the third supply oil passage 32 is operated, and the circuit pressures of the first supply oil passage 27 and the second supply oil passage 28 on the upstream side of the diversion valve 38 are lowered, and the relief valve 36 will be closed.

  At this time, between the time t0 when the stroke sensor 25 detects that the rolling cylinder 11 has reached the stroke end, and the time t1 when the electromagnetic proportional control valve 39 is operated to return to the neutral position 39c after the predetermined time dt. That is, when the raising proportional valve 42 of the second valve unit 33 is operated while the relief valve 36 is in the relief operation, the raising proportional valve 42 is controlled as follows.

  That is, as shown in FIG. 7, the rising proportional valve 42 gradually increases the valve opening so that the raising operation of the lifting cylinder 9 is smoothly performed from the operation start time t2, and the pressure oil supply amount is increased. Is controlled so as to increase gradually. At this time, from the operation start time t2 to the time t1 when the electromagnetic proportional control valve 39 is returned to the neutral position 39c, the flow dividing valve 38 is operated not to the distribution supply position 38c but to the rolling supply position 38a. In this state, no pressure oil is fed into the third supply oil passage 32 of the second valve unit 33.

For this reason, the second valve unit 33 has started to gradually increase the valve opening within the elapsed time t3 between the operation start time t2 and the time t1 when the electromagnetic proportional control valve 39 is returned to the neutral position 39c. As shown in FIG. 7, as the opening degree h1 on the opening degree display line L1 shown in FIG. 7 at the time point t1 when the pressure oil starts to be supplied. Already open to some extent.
When pressure oil is fed into the third supply oil passage 32 of the second valve unit 33 in this state, the upward proportional valve 42 of the second valve unit 33 starts to gradually open the valve opening from the closed state. Instead, as shown in FIG. 7, the operation is performed so that the opening degree is further increased from the state where the opening degree h1 or the opening degree h2 is opened to some extent after the elapsed time t3.

  The opening h1 is between the time t0 when the stroke sensor 25 detects that the stroke end is reached and the time t1 when the electromagnetic proportional control valve 39 is operated to return to the neutral position 39c, that is, the relief valve 36. Indicates the opening degree in a state where the rate of increase in the pressure oil supply amount is controlled to be gradual when the ascending proportional valve 42 of the second valve unit 33 is operated during the relief operation. Yes.

FIG. 7 shows another state in which the raising proportional valve 42 has already been opened to some extent as the opening degree h2 on the opening degree display line L2 indicated by “Operation of the raising proportional valve (2)”. .
The opening degree h2 is the time t1 when the stroke sensor 25 detects that the rolling cylinder 11 has reached the stroke end, and the time t1 when the electromagnetic proportional control valve 39 is returned to the neutral position 39c. The second proportional valve 42 is not operated between the time point t0 and the time point t1 but is not during the relief operation of the relief valve 36. The opening degree in the control state when the ascending proportional valve 42 of the valve unit 33 is operated is shown.

However, the opening indication line L2 indicated by “Operation of the proportional valve for ascending (2)” is the time point t0 when the stroke sensor 25 detects that the rolling cylinder 11 has reached the stroke end as described above. The raising proportional valve 42 of the second valve unit 33 is operated during the time t1 when the electromagnetic proportional control valve 39 is operated to return to the neutral position 39c, that is, while the relief valve 36 is in the relief operation. If not, indicate. That is, when the ascending proportional valve 42 is operated not between the time point t0 and the time point t1 but not during the relief operation of the relief valve 36, the opening indication line L2 is shown. Therefore, although the operation timing of the ascending proportional valve 42 is not correctly displayed in FIG. 7, it is compared with the opening indication line L1 shown in “Operation of the ascending proportional valve (1)”. To make it easier, it is shown on the same time chart.
Assuming that the operation start time of the ascending proportional valve 42 is made coincident with the operation start time of the ascending proportional valve 42 on the opening indicating line L1, on the opening display line L2, at the time t1, The ascending proportional valve 42 is opened by the opening degree h2.

As described above, the ascending proportional valve 42 of the second valve unit 33 has the time t0 when the operation start timing is detected by the stroke sensor 25 to reach the stroke end as described above, and the electromagnetic proportional control valve. The opening / closing condition is changed depending on whether or not the pressure oil is being discharged to the oil tank T side by the relief valve 36 during the time t1 when the operation of the valve 39 is returned to the neutral position 39c. It is configured.
In other words, when the operation of the raising proportional valve 42 is started while the pressure oil is being discharged to the oil tank T side by the relief valve 36, “operation of the raising proportional valve (1) having the opening degree h1 in FIG. As shown in FIG. 7, the opening degree display line L1 changes gently, and the rate of increase in the pressure oil supply amount is shown in “Opening proportional valve operation (2)” having an opening degree h2 in FIG. The control means 14A controls the opening / closing operation of the raising proportional valve 42 so as to be more gradual than the case indicated by the display line L2.

Thus, the valve opening is gradually increased between the time t0 when the stroke sensor 25 detects that the stroke end is reached and the time t1 when the electromagnetic proportional control valve 39 is operated to return to the neutral position 39c. The rising proportional valve 42 of the second valve unit 33 that has started is already open to some extent as indicated by the opening degree h1 in FIG. 7 at the time t1 when pressure oil starts to be supplied. Since the opening degree h1 is based on the above-described moderate increase rate, the opening degree h1 is not opened as much as the opening degree h2 during the non-discharge operation.
Accordingly, since the pressure oil in the range opened at the opening h1 temporarily flows, a shock due to the oil amount in the opened range is unavoidable, but since the opening h1 is not large, the shock Can be as small as negligible.

  The working machine to which the hydraulic device of the present invention is applied may be a riding type rice transplanter, a combine, or a mower, in addition to a tractor.

9 Lifting cylinder 11 Rolling cylinder 14A Control means 36 Relief valve 38 Diverging valve (Flow distribution valve)
38a Rolling supply position 38b Elevating and lowering supply position 38c Distribution supply position 39 Rolling control valve (electromagnetic proportional valve)
39u Ascending position 39d Lowering position 39c Neutral position 42 Elevating control valve 60 Manual operation switch T Oil tank

Claims (3)

The working device connected to the traveling machine body is configured to be driven up and down by a lifting cylinder, and the working device is configured to be capable of rolling control by a rolling cylinder, and is a hydraulic device for a working machine,
The pressure oil supply path to the lifting cylinder is provided with a lift control valve, the pressure oil supply path to the rolling cylinder is provided with a rolling control valve,
A flow rate distribution valve capable of distributing and supplying pressure oil to both the elevation control valve and the rolling control valve;
When the rolling control valve is operated to a rolling operation position for supplying pressure oil to the rolling cylinder side, the control flow is supplied to the rolling cylinder side, and the flow rate is set so that the surplus flow is supplied to the lifting cylinder side. When the distribution valve is controlled and the rolling control valve is operated to a neutral position where the supply of pressure oil to the rolling cylinder side is stopped, the entire amount of upstream pressure oil is supplied to the lift control valve side. A hydraulic device for a working machine comprising control means for controlling the operation of the flow distribution valve.   The hydraulic device for a working machine according to claim 1, wherein the rolling control valve is configured by an electromagnetic proportional control valve, and is configured to be manually operable by operating a manual operation switch.   3. The work machine according to claim 2, wherein a control current for operating the rolling control valve in accordance with a lifting operation by the manual operation switch is configured to gradually increase from a current at the time of the operation by the manual operation switch. Hydraulic device.

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