JP5135288B2 - Hydraulic drive unit for construction machinery - Google Patents

Description

  The present invention relates to a hydraulic drive device for a construction machine. More specifically, the invention relates to a construction machine capable of improving energy loss during a lowering operation of a boom installed in the construction machine and jacking up a vehicle body by the lowering operation of the boom. The present invention relates to a hydraulic drive device.

  A construction machine such as a hydraulic excavator constitutes a swiveling body mounted on a traveling body and an articulated work machine (front) mounted on the rotating body during excavation and earthing work of earth and sand. A compound operation that combines the operation of raising the boom and a compound operation that combines the operation of turning the swivel body and lowering the boom are frequently performed.

  A hydraulic drive device for a construction machine has been proposed (see, for example, Patent Document 1) that ensures good operability in the above-described combined operation and that has a simplified hydraulic circuit that sufficiently reduces energy loss.

JP-A-10-306470

The hydraulic circuit that constitutes the conventional hydraulic drive device for a construction machine described above has a simplified configuration while sufficiently reducing energy loss, and in combined operations such as turning and boom raising or turning and boom lowering. Good operability can be ensured. However, further improvements are desired for the following matters.
(1) During the boom lowering operation, the front weight of the front acts when the boom moves in the air. However, the conventional hydraulic circuit described above applies pressure oil from the hydraulic pump against the front weight during the boom lowering operation. Since the oil is always supplied to the piston rod side oil chamber of the boom cylinder, energy loss occurs due to pressure loss in the pipeline from the hydraulic pump to the boom cylinder.
(2) Further, in the combined operation of the boom lowering operation where the cylinder pressure is low and the operation of the arm or bucket, the pressure oil discharged from the hydraulic pump is supplied to the rod side oil chamber of the boom cylinder. There is also a disadvantage that the amount of pressure oil supplied to the cylinders for driving the arms and buckets is relatively reduced, resulting in poor energy efficiency.
(3) Further, when the construction machine is in operation, pressure oil is applied to the piston rod side oil chamber of the boom cylinder so that the construction machine can be escaped from the marsh or run while moving down a steep slope. , Lowering the boom, pressing the tip of the bucket onto the ground, and raising a part of the vehicle body (jacking up) is required.

  The present invention has been made on the basis of the above-mentioned matters, and the purpose thereof is to follow the configuration of the hydraulic circuit in the hydraulic drive device of the conventional construction machine described above, and to perform the boom lowering operation, the boom lowering operation, the arm, It is an object of the present invention to provide a hydraulic drive device for a construction machine that can reduce pressure loss generated during combined operation with bucket operation and improve energy efficiency, and can generate a large pressing force such as a jack-up force of a vehicle body.

In order to achieve the above object, the first aspect of the present invention is a lower traveling body, an upper revolving body that is pivotably mounted on an upper portion of the lower traveling body, and a rotatable connection to the upper revolving body. Provided in a construction machine having a plurality of driven members including a boom, including at least two hydraulic pumps and a boom cylinder that is supplied with pressure oil discharged from the hydraulic pumps and drives the corresponding driven members, respectively. A construction machine comprising: a plurality of hydraulic actuators; and at least two control valve groups each having at least one direction switching valve for controlling the direction and flow rate of pressure oil supplied from the hydraulic pump to the plurality of hydraulic actuators. In the hydraulic drive device, a regeneration flow rate control valve means for guiding the pressure oil in the bottom side oil chamber of the boom cylinder to the rod side oil chamber, and a boom lowering operation Sometimes, a boom direction switching valve of at least one control valve group provided with a meter-in circuit for controlling a pressure oil flow rate from the hydraulic pump to the rod side oil chamber of the boom cylinder, and a bottom side oil chamber of the boom cylinder Pressure detecting means for detecting the pressure of pressure oil, and a control device for controlling the boom direction switching valve and the regeneration flow rate control valve means, the control device comprising a bottom of the boom cylinder during jack-up operation The storage unit that stores the pressure of the pressure oil in the side oil chamber as a threshold value, the pressure value from the pressure detection means is taken in, the pressure value is compared with the threshold value stored in the storage unit, and the pressure value is the threshold value In the above case, only the regeneration flow rate control valve means is controlled, and when the pressure value is less than the threshold value, the meter-in circuit is further enabled to be effective. Characterized in that an arithmetic unit for controlling switching the over arm directional control valve.

Further , according to a second aspect , in the first aspect , the boom direction switching valve is connected to the bottom oil chamber so that the pressure oil is supplied to the bottom oil chamber of the arm cylinder. It is the direction switch valve for boom lowering / arm cloud further provided with a position.

Furthermore, the third invention, the first or second inventions in Oite, the reproduction flow control valve means, the pressure oil regeneration pipe which connects the boom cylinder bottom-side oil chamber and the rod side oil chamber It is a regeneration flow control valve which makes it possible to control the flow rate.

  According to the hydraulic drive device for a construction machine of the present invention, the boom lowering operation, the boom lowering operation, the arm, and the like, following the configuration of the same valve group and the direction switching valve in the conventional hydraulic drive device for a construction machine. It is possible to reduce the pressure loss generated during the combined operation with the operation of the bucket and improve the energy efficiency, and to generate a large pressing force such as a jack-up force of the vehicle body. As a result, the combined operation of the construction machine work equipment can be further improved, and the construction machine productivity can be further increased. In addition, when the construction machine escapes from the swamp, or when traveling with a steep slope down. Etc. can be supported, and functionality can be improved.

1 is a side view showing a hydraulic excavator to which a first embodiment of a hydraulic drive device for a construction machine according to the present invention is applied. 1 is a hydraulic circuit diagram illustrating a configuration of a first embodiment of a hydraulic drive device for a construction machine according to the present invention. It is a functional block diagram which shows the control function of the control apparatus which comprises 1st Embodiment of the hydraulic drive apparatus of the construction machine of this invention. It is a hydraulic circuit diagram which shows the structure of 2nd Embodiment of the hydraulic drive apparatus of the construction machine of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a hydraulic drive device for a construction machine according to the present invention will be described with reference to the drawings.

  A first embodiment of a hydraulic drive device for a construction machine according to the present invention will be described with reference to FIGS. FIG. 1 is a side view showing a hydraulic excavator to which a first embodiment of a hydraulic drive device for a construction machine according to the present invention is applied, and FIG. 2 is a first embodiment of the hydraulic drive device for a construction machine according to the present invention. FIG. 3 is a functional block diagram showing a control function of the control device constituting the first embodiment of the hydraulic drive device for the construction machine according to the present invention.

  In FIG. 1, a so-called loader type large hydraulic excavator is shown as a hydraulic excavator that is a construction machine. The hydraulic excavator is connected to a lower traveling body 55, an upper revolving body 56 provided on the upper portion of the lower traveling body 55 via a swivel bearing 57, and a revolving motion to the upper revolving body 56. An articulated front work machine 58 is provided. The bucket 52 provided in the multi-joint type front working machine 58 is arranged so that the opening is directed forward when the ground is in contact, and the bucket opening / closing cylinder 4 is mounted on the bucket 52 as illustrated. In addition, the boom cylinder 1, the bucket cylinder 2, the arm cylinder 3, and the bucket opening / closing cylinder 4 are each raised (or shortened) by a boom raising (or boom lowering), arm pushing (or arm pulling), bucket cloud (or bucket dumping). ), And the bucket is closed (or opened).

Next, a hydraulic circuit diagram showing the configuration of the first embodiment of the hydraulic drive device for the construction machine according to the present invention applied to the above-described hydraulic excavator will be described.
In FIG. 2, this hydraulic drive device is supplied with three hydraulic pumps 8, 9, 10 driven by an engine (not shown) and pressure oil discharged from these hydraulic pumps 8-10, and a boom 51, a bucket 52, And the seven hydraulic actuators 1 to 7 including the boom cylinder 1, the bucket cylinder 2, and the arm cylinder 3 that respectively drive the arms 53, and the direction of the pressure oil supplied from the hydraulic pumps 8 to 10 to the hydraulic actuators 1 to 7, respectively. And 12 directional control valves 11-1 to 13-4 for controlling the flow rate.

  In addition to the boom cylinder 1, the bucket cylinder 2, and the arm cylinder 3, the hydraulic actuators 1 to 7 are connected to the left and right traveling motors 6 and 7 that drive the lower traveling body 55 of the hydraulic excavator and the lower traveling body 55. A turning motor 5 for turning the upper turning body 56 and an opening / closing cylinder 4 for opening / closing the bucket 52 are included.

  The direction switching valves 11-1 to 13-4 are all center bypass type switching valves, and are divided into three valve groups: a first valve group 11, a second valve group 12, and a third valve group 13. . The first valve group 11 includes a left traveling direction switching valve 11-1 connected only to the left traveling motor 7 among the hydraulic actuators 1 to 7, a bottom side oil chamber 1 </ b> A of the boom cylinder 1, and a bottom side oil of the bucket cylinder 2. Boom raising / bucket cloud direction switching valve 11-2 connected to chamber 2A, opening / closing direction switching valve 11-3 connected only to opening / closing cylinder 4, and first arm direction connecting only to arm cylinder 3 It is comprised from the switching valve 11-4. The second valve group 12 includes a right traveling direction switching valve 12-1 connected only to the right traveling motor 6 among the hydraulic actuators 1 to 7, and a second arm direction switching valve 12-connected only to the arm cylinder 3. 2. The first boom direction switching valve 12-3 connected only to the boom cylinder 1 and the second bucket direction switching valve 12-4 connected only to the bucket cylinder 2. The third valve group 13 includes a turning direction switching valve 13-1 connected only to the turning motor 5 of the hydraulic actuators 1 to 7, and a second boom direction connected only to the bottom side oil chamber 1 </ b> A of the boom cylinder 1. It is connected only to the switching valve 13-2, the boom lowering / arm cloud directional switching valve 13-3 connected to the rod side oil chamber 1B of the boom cylinder 1 and the bottom side oil chamber 3A of the arm cylinder 3, and the bucket cylinder 2. The third bucket direction switching valve 13-4.

  The bottom oil chamber 1A of the boom cylinder 1, the boom raising / bucket cloud direction switching valve 11-2, the first boom direction switching valve 12-3, and the second boom direction switching valve 13-2 are the main oil pipes. 101, the rod side oil chamber 1B of the boom cylinder 1, the first boom direction switching valve 12-3, and the boom lowering / armcloud direction switching valve 13-3 are connected by the main oil pipe 102. ing. Further, the bottom side oil chamber 2A of the bucket cylinder 2, the boom raising / bucket cloud direction switching valve 11-2, the second bucket direction switching valve 12-4, and the third bucket direction switching valve 13-4 are: The main oil pipe 201 connects the rod side oil chamber 2B of the bucket cylinder 2, and the second bucket direction switching valve 12-4 and the third bucket direction switching valve 13-4 through the main oil pipe 202. ing. Further, the bottom side oil chamber 3A of the arm cylinder 3, the first arm direction switching valve 11-4, the second arm direction switching valve 12-2, the boom lowering / arm cloud direction switching valve 13-3, The main oil pipe 301 connects the rod side oil chamber 3B of the arm cylinder 3, and the first arm direction switching valve 11-4 and the second arm direction switching valve 12-2 by a main oil pipe 302. ing. Further, the bottom side oil chamber 4A of the bucket opening / closing cylinder 4 and the opening / closing direction switching valve 11-3 are connected by a main oil pipe 401, and the rod side oil chamber 4B of the bucket opening / closing cylinder 4 is switched to the opening / closing direction switching. The valve 11-3 is connected by a main oil pipe 402.

  The hydraulic pumps 8 to 10 are variable displacement pumps respectively driven by an engine (not shown), and the first hydraulic pump 8 that discharges the pressure oil to the first valve group 11 and the pressure oil to the second valve group 12. And a third hydraulic pump 10 that discharges pressure oil to the third valve group 13. In the first valve group 11, the left travel switching valve 11-1 includes other boom raising / bucket cloud direction switching valve 11-2, opening / closing direction switching valve 11-3, and first arm direction switching. It is connected to the tandem so as to supply pressure oil from the first hydraulic pump 8 to the left travel motor 7 with priority over the valve 11-4, and the boom raising / bucket cloud direction switching valve 11-2 is opened and closed. The direction switching valve 11-3 and the first arm direction switching valve 11-4 are connected in parallel to each other. Further, in the second valve group 12, the right travel switching valve 12-1 includes the other second arm direction switching valve 12-2, the first boom direction switching valve 12-3, and the second bucket direction. It is connected to the tandem so as to supply pressure oil from the second hydraulic pump 9 to the right traveling motor 6 with priority over the switching valve 12-4, and the second arm direction switching valve 12-2, first The boom direction switching valve 12-3 and the second bucket direction switching valve 12-4 are connected in parallel to each other. Further, in the third valve group 13, the turning direction switching valve 13-1 and the second boom direction switching valve 13-2 are the boom lowering / armcloud direction switching valve 13-3 and the third bucket direction switching. It is connected in tandem so that the pressure oil of the third hydraulic pump 10 can be supplied to the bottom side oil chamber of the swing motor 5 and the boom cylinder 1 in preference to the valve 13-4. Further, the turning direction switching valve 13-1 and the second boom direction switching valve 13-2 are connected in parallel to each other, and the boom lowering / armcloud direction switching valve 13-3 and the third bucket direction. The switching valves 13-4 are also connected to each other in parallel.

  The main pipeline 101 connected to the bottom-side oil chamber 1A of the boom cylinder 1 and the main pipeline 102 connected to the rod-side oil chamber 1B are connected by a regeneration pipeline 110, and the regeneration pipeline 110 is connected to the regeneration pipeline 110. A boom regenerative flow control valve 18 comprising a variable throttle 111 for controlling the flow of pressure oil from the bottom side oil chamber 1A of the boom cylinder 1 to the rod side oil chamber 1B to a desired throttle amount, for example, comprising an electromagnetic proportional valve. Is provided. A check valve 112 that allows the flow of pressure oil from the bottom side oil chamber 1A to the rod side oil chamber 1B and blocks the reverse flow from the boom regeneration flow control valve 18 to the rod side oil chamber 1B side. Is provided. Thereby, the pressure oil in the bottom side oil chamber 1A of the boom cylinder 1 is guided to the rod side oil chamber 1B. Further, a pressure sensor 19 for detecting the pressure of pressure oil in the bottom side oil chamber 1A is provided on the bottom side oil chamber 1A side from the boom regeneration flow control valve 18. The pressure sensor 19 outputs the detected pressure signal of the pressure oil to the controller 15 as a control device of the hydraulic drive device.

  Further, the hydraulic drive apparatus shown in FIG. 2 further includes hydraulic actuators 1 to 5 for instructing operations of the boom 51, bucket 52, arm 53, lower traveling body 55, and upper traveling body 56, which are driven members. Are provided with a plurality of operating lever devices including the boom operating lever device 14 (except for the boom operating lever device 14 are not shown). The boom operation lever device 14 outputs a voltage signal corresponding to the operation amount and operation direction of the operation lever to the controller 15 as an operation signal.

  The controller 15 receives an operation signal from the boom operation lever device 14, and the boom raising electromagnetic proportional valve 16, the boom lowering electromagnetic proportional valve 17, the boom regenerative flow rate control valve 18, and the jackup electromagnetic proportional valve. 20, a current signal calculated by a calculation unit described later is output. The primary port side of the electromagnetic proportional valves 16, 17 and 20 to which this current signal is applied is connected to a hydraulic power source, for example, a pilot pump, not shown in detail, and is proportional to the current signal on the secondary port side. It is possible to generate a pilot pressure. This pilot pressure causes each switching valve, which will be described later, to stroke through the pilot lines 160, 170, and 200. Further, the electromagnetic proportional valve 18 strokes in proportion to the current, and adjusts the throttle amount of the variable throttle 111.

  The secondary port side of the boom raising electromagnetic proportional valve 16 is connected via a pilot line 160 to the corresponding boom raising / bucket cloud direction switching valve 11-2, first boom direction switching valve 12-3, and second boom. It is connected to each drive part 11-2a, 12-3b, 13-2a of the directional control valve 13-2, and the secondary port side of the boom lowering electromagnetic proportional valve 17 corresponds via the pilot line 170. Connected to the drive units 12-3a and 13-2b of the first boom direction switching valve 12-3 and the second boom direction switching valve 13-2, and the secondary port of the jack-up electromagnetic proportional valve 20 The side is connected to the drive unit 13-3b of the corresponding boom lowering / armcloud direction switching valve 13-3 via the pilot line 200. Thereby, the boom raising / bucket cloud directional switching valve 11-2, the first boom directional switching valve 12-3, and the second boom directional switching, which are the corresponding directional switching valves, according to the operation signal from the operation lever device 14. The valve 13-2 and the boom lowering / arm cloud direction switching valve 13-3 are switched to control the direction and flow rate of the pressure oil supplied from the first to third hydraulic pumps 8 to 10 to the boom cylinder 1. ing.

  FIG. 3 is a functional block diagram showing the control function of the controller 15. The boom raising electromagnetic proportional valve 16, the boom for the operation signal of the operation lever device 14 that is an input signal and the pressure detection signal of the pressure sensor 19 are shown. A control function of drive signals to the lowering electromagnetic proportional valve 17, the boom regeneration flow control valve 18, and the jack-up electromagnetic proportional valve 20 is shown. In FIG. 3, a controller 15 includes a drive signal calculator 15d for the boom lowering electromagnetic proportional valve 17 and the jackup electromagnetic proportional valve 20, a drive signal calculator 15e for the boom regeneration flow rate control valve 18, and a boom raising solenoid valve. These are the drive signal calculator 15f of the electromagnetic proportional valve 16, the pressure oil pressure Pb of the bottom side oil chamber 1A of the boom cylinder 1, and the pressure oil pressure of the bottom side oil chamber 1A of the boom cylinder 1 during the jack-up operation. The output of the comparison judgment unit 15g that performs a magnitude comparison judgment with the pressure threshold value Pbo and the output Pi17 of the drive signal calculator 15d or the zero signal is not changed suddenly by the output of the comparison judgment unit 15g. Thus, for example, it has a calculating part provided with the filter part 15i which consists of a primary delay element.

  In addition, the controller 15 lowers the output voltage of one of the input unit 15a for converting the output voltage of the pressure sensor 19 into the pressure Pb of the pressure oil in the bottom side oil chamber 1A of the boom cylinder 1, and the boom operating lever device 14. It has an input conversion part provided with the input part 15b which converts into lever operation amount, and the input part 15c which converts the other output voltage of the boom operation lever apparatus 14 into boom raising lever operation amount.

  Further, the controller 15 lowers the boom according to the target pilot pressure Pi17 that is the output of the drive signal calculator 15d and the drive unit 15j that drives the jack-up electromagnetic proportional valve 20 according to the target pilot pressure from the filter unit 15i. A drive unit 15k that drives the electromagnetic proportional valve 17; a drive unit 15m that drives the boom regeneration flow rate control valve 18 according to the target current i18 that is the output of the drive signal calculator 15e; and an output of the drive signal calculator 15f. And an output unit including a drive unit 15n for driving the boom raising electromagnetic proportional valve 16 in accordance with the target pilot pressure Pi16.

  In addition, the operation pattern with respect to the lever operation amount in each of the drive signal calculators 15d, 15e, 15f (the target pilot pressures Pi17, Pi16, i18 with respect to the lever operation amount) and the pressure threshold value Pbo in the comparison determination unit 15g are shown in FIG. 3 is stored in advance in the storage unit of the controller 15 as a table as shown in FIG. In these operation tables, the operation amount-drive signal characteristics are set so that the actuator operation characteristics are optimal for the operator with respect to the operation amount signals in accordance with the characteristics of the corresponding actuators.

  In other words, the boom lowering drive signal calculator 15d receives the boom lowering lever operation amount from the boom operating lever device 14, and supplies the boom lowering electromagnetic proportional valve 17 and the jackup electromagnetic proportional valve 20 based on the illustrated table. The target pilot pressure (drive signal to each electromagnetic proportional valve) Pi17, which is a control signal, is calculated and output. For the boom lowering electromagnetic proportional valve 17, a drive signal is output via the drive unit 15k.

  On the other hand, regarding the jack-up electromagnetic proportional valve 20, first, in the comparison determination unit 15g of the calculation unit, the pressure value Pb of the pressure oil in the bottom side oil chamber 1A of the boom cylinder 1 and the pressure threshold value Pbo stored in the storage unit When the pressure value Pb is less than the pressure threshold value Pbo, the value of the target pilot pressure Pi17 described above is selected as the output Pi20 of the signal switching unit 15h, and the target pilot pressure is selected via the filter unit 15i and the drive unit 15k. The drive signal for Pi17 is output. When the pressure value Pb is equal to or greater than the pressure threshold value Pbo, a zero signal is selected and output as the output Pi20 of the signal switching unit 15h, and the jack-up electromagnetic proportional valve 20 is not driven, so no pilot pressure is generated on the secondary port side. .

  Further, the boom regeneration drive signal calculator 15e receives the boom lowering lever operation amount from the boom operation lever device 14, and based on the illustrated table, a target current (a control signal to the boom regeneration flow rate control valve 18). The drive signal i18 to the electromagnetic proportional valve is calculated, and the drive signal is output via the drive unit 15m.

  Further, the boom raising drive signal calculator 15f inputs the boom raising lever operation amount from the boom operating lever device 14, and the target pilot pressure which is a control signal to the boom raising electromagnetic proportional valve 16 based on the illustrated table. (Drive signal to electromagnetic proportional valve) Pi16 is calculated, and a drive signal is output via the drive unit 15n.

  That is, as a major feature of the present embodiment, the controller 15 stores the pressure oil pressure in the bottom oil chamber 1A of the boom cylinder 1 during the jackup operation as the threshold value Pbo, and the pressure value Pb from the pressure sensor 19 is stored. When the pressure value Pb is equal to or greater than the threshold value Pbo, only the regeneration flow control valve 18 is controlled, and when the pressure value Pb is less than the threshold value Pbo, the meter-in circuit is further enabled. For this purpose, the electromagnetic proportional valve 20 for jack-up is controlled to control the switching of the boom direction switching valve 13-3.

  In the present embodiment shown in FIG. 2, the input / output of the controller 15 is shown only for the boom cylinder 1 for convenience of explanation, and the description of the operation lever device and the electromagnetic proportional valve in other hydraulic actuators is omitted. ing.

  Next, the operation of the first embodiment of the hydraulic drive system for a construction machine according to the present invention having the above-described configuration will be described.

(1) Boom raising operation
First, in the case of the boom raising operation, when the operation lever of the boom operation lever device 14 is operated to the boom raising side, a voltage signal corresponding to the lever operation amount is input to the controller 15. The controller 15 outputs a current signal corresponding to the voltage signal to the boom raising electromagnetic proportional valve 16. The boom raising electromagnetic proportional valve 16 generates a pilot pressure proportional to the current, and this pilot pressure is a drive unit for the boom raising / bucket cloud direction switching valve 11-2 connected to the pilot line 160 on the boom raising side. 11-2a, the drive unit 12-3b of the first boom direction switching valve 12-3, and the drive unit 13-2a of the second boom direction switching valve 13-2, and these direction switching valves 11-2, 12-3 and 13-2 are respectively switched to the boom raising side switching position.

  Then, the pressure oil of the first to third hydraulic pumps 8 to 10 flows into the bottom side oil chamber 1A of the boom cylinder 1 through these three switching valves. At this time, the return oil from the rod side oil chamber 1B is discharged to the tank through the switching position of the first boom direction switching valve 12-3 connected to the oil chamber 1B. This raises the boom 51.

(2) Boom lowering operation in the air
Next, in the case of the boom lowering operation, when the operation lever of the boom operation lever device 14 is operated to the boom lowering side, a voltage signal corresponding to the lever operation amount is input to the controller 15. The controller 15 outputs a current signal corresponding to the voltage signal to the boom lowering electromagnetic proportional valve 17 and the boom regeneration flow control valve 18. The electromagnetic proportional valve 17 generates a pilot pressure proportional to the current, and this pilot pressure is connected to the pilot line 170 on the boom lowering side, the drive unit 12-3a of the first boom direction switching valve 12-3, and Guided to the drive unit 13-2b of the second boom direction switching valve 13-2, the direction switching valves 12-3 and 13-2 are switched to the boom lower side switching position.

  As a result, the pressure oil sealed in the bottom side oil chamber 1A of the boom cylinder 1 returns to the tank via the first boom direction switching valve 12-3 and the second boom direction switching valve 13-2. Further, the boom regeneration flow control valve 18 strokes in proportion to the current, and drives the throttle amount of the variable throttle 111 to the open side. At this time, since the holding pressure is generated in the bottom side oil chamber 1A of the boom cylinder 1 due to the weight of the boom 51, the bottom side oil chamber is opened by opening the variable throttle 111 of the boom regeneration flow control valve 18. Part of the outflow flow rate of the pressure oil from 1A is introduced (circulated) into the rod-side oil chamber 1B through the boom regeneration flow control valve 18 and the check valve 112.

  As described above, in the case of the boom lowering operation in the air operation, the holding pressure is generated in the bottom side oil chamber 1 </ b> A of the boom cylinder 1. The controller 15 detects the pressure in the bottom oil chamber 1A with the pressure sensor 19, and when the detected pressure is equal to or higher than the predetermined pressure Pbo, it does not output current to the jack-up electromagnetic proportional valve 20. Therefore, the boom lowering / arm cloud direction switching valve 13-3 remains neutral, and the pressure oil from the third hydraulic pump 10 is not supplied to the rod side oil chamber 1 </ b> B of the boom cylinder 1.

(3) Jack-up operation
Further, when the boom 51 is continuously lowered and the bucket 52 comes into contact with the ground, for example, a pressing force is applied to the front attachment. At this time, since a tensile force acts on the boom cylinder 1, the pressure of the pressure oil in the bottom side oil chamber 1A decreases. That is, in addition to the boom lowering operation described above, when the pressure in the bottom oil chamber 1A of the boom cylinder 1 is detected and it is determined that the jack is up, an operation different from the above (2) is performed. Specifically, when the pressure of the bottom oil chamber 1A is detected by the pressure sensor 19, and the detected pressure is less than a predetermined pressure Pbo, the boom lowering voltage signal of the operation lever of the boom operation lever device 14 is the controller. 15, the controller 15 outputs a current signal corresponding to the voltage signal to the jack-up electromagnetic proportional valve 20 together with the boom lowering electromagnetic proportional valve 17 and the boom regeneration flow rate control valve 18. The boom lowering electromagnetic proportional valve 17 and the boom regeneration flow rate control valve 18 perform the same operation as the above-described (2).

  On the other hand, the jack-up electromagnetic proportional valve 20 generates a pilot pressure proportional to the current, and this pilot pressure is applied to the boom lowering / armcloud directional switching valve 13-3 connected to the jack-up pilot line 200. Guided by the drive unit 13-3b, the direction switching valve 13-3 is switched to the switching position on the boom (jack-up) side. Then, the pressure oil of the third hydraulic pump 10 flows into the rod side oil chamber 1B of the boom cylinder 1 through this switching valve. As a result, the pressure of the pressure oil in the rod-side oil chamber 1B is increased and a strong pressing force is generated, so that a jackup force can be secured.

  As described above, in the boom lowering operation that does not require pressing force, the pressure oil from the hydraulic pump is not supplied to the rod side oil chamber 1B of the boom cylinder 1, and only the return oil from the bottom side oil chamber 1A is regenerated. When jacking up without supplying a flow rate, a strong pressing force can be secured by supplying pressure oil from the hydraulic pump to the rod side oil chamber 1B of the boom cylinder 1.

  According to the first embodiment of the hydraulic drive device for a construction machine of the present invention described above, in the boom lowering operation that does not require a pressing force, only regeneration of the return oil from the bottom side oil chamber 1A of the boom cylinder 1 is performed. In this case, the pressure oil flow from the hydraulic pump to the rod side oil chamber 1B is not supplied to the rod side oil chamber 1B. Pressure loss can be reduced, and a pressing force can be generated when jacking up. As a result, the energy efficiency of the hydraulic circuit can be improved, and the productivity and workability of the construction machine can be improved.

  Further, in the combined operation of the boom lowering operation where the cylinder pressure is low and the arm or bucket operation where the cylinder pressure is higher than the boom lowering operation, the flow rate is distributed to the operation side where the cylinder pressure is high in the conventional circuit. In this case, the meter-in of the switching valve for lowering the boom with low cylinder pressure had to be throttled, and energy loss was generated here. According to the first embodiment of the hydraulic drive device for a construction machine of the present invention, only the boom lowering / armcloud direction switching valve 13-3 has a boom lowering meter-in, and this direction switching valve 13- No. 3 is in a neutral position and does not cause switching in the boom lowering operation in the air operation that does not require pressing force. Therefore, unlike the conventional circuit, it is not necessary to throttle the meter-in of the direction switch valve for lowering the boom in order to distribute the flow rate to the operating side where the cylinder pressure is high, and energy loss due to the meter-in throttling does not occur. As a result, the energy efficiency of the hydraulic circuit can be improved.

  Further, in the combined operation of the boom lowering operation and the arm or bucket operation as described above, in the conventional circuit, the flow from the hydraulic pump is taken for the boom lowering operation, and the operation of the other operation of the arm or bucket is performed. It was slowing down. According to the first embodiment of the hydraulic drive device for a construction machine of the present invention, in the boom lowering operation that does not require pressing force, the pressure oil from the hydraulic pump is supplied to the rod side oil chamber 1B of the boom cylinder 1. Therefore, the operation speed of other operations can be made faster than that of the conventional circuit. As a result, the energy efficiency of the hydraulic circuit can be improved, and the productivity and workability of the construction machine can be improved.

  In addition, according to the first embodiment of the hydraulic drive device for a construction machine of the present invention, in a large construction machine that constitutes a hydraulic circuit using a large number of control valves having a simple circuit configuration, it is the same as the conventional circuit. With a simple circuit configuration using the control valve and the switching valve, the pressure loss can be reduced and the energy efficiency can be improved, and a large pressing force such as a jack-up force of the vehicle body can be generated.

  In the above-described embodiment, the case where the tip of the piston rod of the boom cylinder 1 is connected to the upper swing body 56 and the base end of the boom cylinder 1 is connected to the boom 51 has been described. The present invention can also be applied to the case where the distal end of the boom cylinder 1 is connected to the boom 51 and the base end of the boom cylinder 1 is connected to the upper swing body 56.

  Next, a second embodiment of the hydraulic drive device for the construction machine according to the present invention will be described with reference to FIG. FIG. 4 is a hydraulic circuit diagram showing the configuration of the second embodiment of the hydraulic drive system for the construction machine according to the present invention. In FIG. 4, the same reference numerals as those shown in FIGS. 1 to 3 are the same or corresponding parts, and the description thereof is omitted.

  This embodiment is an embodiment in the case where the structure shown in FIG. 2 is applied to a two-pump hydraulic drive device provided in a backhoe type hydraulic excavator, and FIG. 4 is a hydraulic pressure diagram showing the configuration of the hydraulic drive device. It is a circuit diagram. In FIG. 4, the hydraulic drive device of the present embodiment roughly removes the third hydraulic pump 10 and its peripheral devices from the structure of FIG. 2, and further corresponds to the two-pump system. The number is reduced and the first and second valve groups 21 and 22 are integrated.

  That is, the first valve group 21 is provided with four direction switching valves 21-1, 21-2, 21-3, and 21-4. Among these, the left travel direction switching valve 21-1 and the first arm direction switching valve 21-4 are left in the same positions as in FIG. 2, and the first bucket direction switching valve 21-3 and the first direction switching valve 21-3 are the same. The one-boom direction switching valve 21-2 is the one that was in the second valve group 12 of FIG. The left travel direction switching valve 21-1 can supply pressure oil from the first hydraulic pump 8 to the left travel motor 7 with priority over the other direction switching valves 21-2, 21-3, and 21-4. The first boom oil direction switching valve 21-2, the first bucket direction switching valve 21-3, and the first arm direction switching valve 21-4 are connected in parallel to each other. .

  On the other hand, the second valve group 22 is provided with five direction switching valves 22-1, 22-2, 22-3, 22-4, and 22-5. Among these, the turning direction switching valve 22-1 and the second boom direction switching valve 22-2 are relocated from the third valve group 13 of FIG. 2, and the boom lowering / bucket cloud direction switching is performed. The valve 22-3 is newly arranged, and the second arm direction switching valve 22-4 and the right traveling direction switching valve 22-5 are obtained by changing the position of the second valve group 12 of FIG.

  Then, a turning direction switching valve 22-1 and a second boom direction switching valve 22-2, a boom lowering / bucket cloud direction switching valve 22-3 and a second arm direction switching valve 22-4, and right traveling The direction switching valve 22-5 is connected in tandem so that the pressure oil of the first hydraulic pump 8 can be preferentially supplied to the corresponding actuator in this order. Further, the turning direction switching valve 22-1 and the second boom direction switching valve 22-2 are connected in parallel to each other. Similarly, the boom lowering / bucket cloud direction switching valve 22-3 and the second arm direction are connected. The switching valve 22-4 is connected to each other in parallel.

  Further, the secondary port side of the boom raising electromagnetic proportional valve 16 is connected to each drive unit of the corresponding first boom direction switching valve 21-2 and second boom direction switching valve 22-2 via the pilot line 160. The secondary port side of the boom lowering solenoid proportional valve 17 is connected to the corresponding first boom direction switching valve 21-2, second boom via the pilot line 170. Are connected to the drive units 21-2a and 22-2b of the directional control valve 22-2, and the secondary port side of the jack-up electromagnetic proportional valve 20 is connected to the corresponding boom lowering / It is connected to the drive unit 22-3b of the bucket cloud direction switching valve 22-3.

  Accordingly, the first boom direction switching valve 21-2, the second boom direction switching valve 22-2, the boom lowering / bucket cloud direction switching, which are the corresponding direction switching valves, according to the operation signal from the operation lever device 14. The valve 22-3 is switched to control the direction and flow rate of the pressure oil supplied from the first and second hydraulic pumps 8 and 9 to the boom cylinder 1. The other structure is almost the same as that of the hydraulic drive apparatus shown in FIG.

  Next, the operation of the second embodiment of the hydraulic drive device for the construction machine according to the present invention configured as described above will be described.

(1) Boom raising operation
First, in the case of the boom raising operation, when the operation lever of the boom operation lever device 14 is operated to the boom raising side, a voltage signal corresponding to the lever operation amount is input to the controller 15. The controller 15 outputs a current signal corresponding to the voltage signal to the boom raising electromagnetic proportional valve 16. The boom raising electromagnetic proportional valve 16 generates a pilot pressure proportional to the current, and this pilot pressure is the drive unit 21-of the first boom direction switching valve 21-2 connected to the boom raising side pilot line 160. 2b and the second boom direction switching valve 22-2 are guided to the drive unit 22-2a to switch the direction switching valves 21-2 and 22-2 to the boom raising side switching position.

  Then, the pressure oil of the first and second hydraulic pumps 8 and 9 flows into the bottom side oil chamber 1A of the boom cylinder 1 through these two switching valves. At this time, the return oil from the rod side oil chamber 1B is discharged to the tank through the switching position of the first boom direction switching valve 21-2 connected to the oil chamber 1B. This raises the boom 51.

(2) Boom lowering operation in the air
Next, in the case of the boom lowering operation, when the operation lever of the boom operation lever device 14 is operated to the boom lowering side, a voltage signal corresponding to the lever operation amount is input to the controller 15. The controller 15 outputs a current signal corresponding to the voltage signal to the boom lowering electromagnetic proportional valve 17 and the boom regeneration flow control valve 18. The electromagnetic proportional valve 17 generates a pilot pressure proportional to the current, and this pilot pressure is connected to the pilot line 170 on the boom lowering side, the drive unit 21-2a of the first boom direction switching valve 21-2, and Guided to the drive section 22-2b of the second boom direction switching valve 22-2, the direction switching valves 21-2 and 22-2 are switched to the switching position on the boom lowering side.

  As a result, the pressure oil sealed in the bottom side oil chamber 1A of the boom cylinder 1 returns to the tank via the first boom direction switching valve 21-2 and the second boom direction switching valve 22-2. Further, the boom regeneration flow control valve 18 strokes in proportion to the current, and drives the throttle amount of the variable throttle 111 to the open side. At this time, since the holding pressure is generated in the bottom side oil chamber 1A of the boom cylinder 1 due to the weight of the boom 51, the bottom side oil chamber is opened by opening the variable throttle 111 of the boom regeneration flow control valve 18. Part of the outflow flow rate of the pressure oil from 1A is introduced (circulated) into the rod-side oil chamber 1B through the boom regeneration flow control valve 18 and the check valve 112.

  As described above, in the case of the boom lowering operation in the air operation, the holding pressure is generated in the bottom side oil chamber 1 </ b> A of the boom cylinder 1. The controller 15 detects the pressure in the bottom oil chamber 1A with the pressure sensor 19, and when the detected pressure is equal to or higher than the predetermined pressure Pbo, it does not output current to the jack-up electromagnetic proportional valve 20. Therefore, the boom lowering / bucket cloud direction switching valve 22-3 remains neutral, and the pressure oil from the second hydraulic pump 9 is not supplied to the rod side oil chamber 1B of the boom cylinder 1.

(3) Jack-up operation
Further, when the boom 51 is continuously lowered and the bucket 52 comes into contact with the ground, for example, a pressing force is applied to the front attachment. At this time, since a tensile force acts on the boom cylinder 1, the pressure of the pressure oil in the bottom side oil chamber 1A decreases. That is, in addition to the boom lowering operation described above, when the pressure in the bottom oil chamber 1A of the boom cylinder 1 is detected and it is determined that the jack is up, an operation different from the above (2) is performed. Specifically, when the pressure in the bottom oil chamber 1A is detected by the pressure sensor 19, and the detected pressure is less than a predetermined pressure Pbo, the boom lowering voltage signal of the operation lever of the boom operation lever device 14 is 15, the controller 15 outputs a current signal corresponding to the voltage signal to the jack-up electromagnetic proportional valve 20 together with the boom lowering electromagnetic proportional valve 17 and the boom regeneration flow rate control valve 18. The boom lowering electromagnetic proportional valve 17 and the boom regeneration flow rate control valve 18 perform the same operation as the above-described (2).

  On the other hand, the jack-up electromagnetic proportional valve 20 generates a pilot pressure proportional to the current, and this pilot pressure is applied to the boom lowering / bucket cloud directional control valve 22-3 connected to the jack-up pilot line 200. Guided to the drive unit 22-3b, the direction switching valve 22-3 is switched to the switching position on the boom (jack-up) side. Then, the pressure oil of the second hydraulic pump 9 flows into the rod side oil chamber 1B of the boom cylinder 1 through this switching valve. As a result, the pressure of the pressure oil in the rod-side oil chamber 1B is increased and a strong pressing force is generated, so that a jackup force can be secured.

  According to the second embodiment of the hydraulic drive device for a construction machine of the present invention described above, the same effects as those of the first embodiment described above can be obtained.

DESCRIPTION OF SYMBOLS 1 Boom cylinder 2 Bucket cylinder 3 Arm cylinder 4 Opening / closing cylinder 5 Turning motor 6 Right traveling motor 7 Left traveling motor 8 1st hydraulic pump 9 2nd hydraulic pump 10 3rd hydraulic pump 11 1st valve group 12 2nd valve group 13 1st Three valve group 14 Boom control lever device 15 Controller 16 Boom raising electromagnetic proportional valve 17 Boom lowering electromagnetic proportional valve 18 Boom regenerative flow control valve 19 Pressure sensor 20 Jacking up electromagnetic proportional valve 51 Boom 52 Basket 53 Arm 55 Lower part Traveling body 56 Upper swing body 57 Swivel base bearing 58 Front work machine 101 Main pipeline 102 Main pipeline 110 Regeneration pipeline 111 Variable throttle 112 Check valve

Claims (3)

Provided in a construction machine including a lower traveling body, an upper swing body that is pivotably mounted on the upper portion of the lower traveling body, and a plurality of driven members that are pivotally connected to the upper swing body A plurality of hydraulic actuators including a boom cylinder that is supplied with pressure oil discharged from the hydraulic pump and drives the corresponding driven member, and from the hydraulic pump to the plurality of hydraulic actuators. A hydraulic drive device for a construction machine having at least two control valve groups each including at least one direction switching valve for controlling the direction and flow rate of the pressure oil supplied to
Regenerative flow rate control valve means for guiding the pressure oil in the bottom side oil chamber of the boom cylinder to the rod side oil chamber;
A boom direction switching valve of at least one control valve group provided with a meter-in circuit for controlling a pressure oil flow rate from the hydraulic pump to the rod side oil chamber of the boom cylinder during a boom lowering operation;
Pressure detecting means for detecting the pressure of the pressure oil in the bottom oil chamber of the boom cylinder;
A control device for controlling the boom direction switching valve and the regeneration flow rate control valve means ;
The control device takes in a pressure value from the pressure detection means, a storage unit storing the pressure oil pressure in the bottom oil chamber of the boom cylinder at the time of jackup operation, and the pressure value and the storage unit When the pressure value is equal to or greater than the threshold value, only the regeneration flow rate control valve means is controlled. When the pressure value is less than the threshold value, the meter-in circuit is further activated. In order to achieve this, a hydraulic drive device for a construction machine , comprising: a calculation unit that switches and controls the boom direction switching valve . The hydraulic drive device for a construction machine according to claim 1 ,
The boom direction switching valve further includes an arm cloud switching position that can be connected to the bottom oil chamber so as to supply pressure oil to the bottom oil chamber of the arm cylinder. A hydraulic drive device for a construction machine. The hydraulic drive device for a construction machine according to claim 1 or 2 ,
The regenerative flow rate control valve means is a regenerative flow rate control valve capable of controlling the flow rate of pressure oil in the regenerative pipe line connecting the bottom side oil chamber and the rod side oil chamber of the boom cylinder. Hydraulic drive device.

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