JPH10331211A - Hydraulic circuit device of construction machinery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively use a hydraulic pump for an additional attachment in a hydraulic circuit device of construction machinery and to increase travelling speed without impairing straight advancement travelling efficiency. SOLUTION: A synchronizing shunt valve 50 is connected to the lower part of a center bypass line 53 passing through a directional control valve 40 of a blade valve device 110, and the synchronizing shunt valve 50 is connected to a travelling motor 4a through speed increasing control valves 51 and 52. Pilot pressure RR or RF and LR or LF caused by both right and left travelling pilot control valves 15 and 16 is guided by directional control valves 13 and 14, at the same time, the pilot pressure is also led to the speed increasing control valves 51 and 52, and the speed increasing control valves 51 and 52 are interlocked with the directional control valves 13 and 14 to switch.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit device for a construction machine equipped with an additional attachment such as a blade, and more particularly to a hydraulic circuit for a construction machine for effectively utilizing a fixed displacement hydraulic pump provided for the additional attachment. Related to the device.

[0002]

2. Description of the Related Art A typical example of a construction machine equipped with an additional attachment is a hydraulic excavator with a blade. FIG. 3 shows the hydraulic excavator with the blade.

[0003] In Fig. 3, a hydraulic excavator with blades includes a lower traveling body 1, an upper revolving superstructure 2, and a work front 3, and the lower traveling body 1 has traveling motors 4 (right traveling motor 4a, left traveling motor 4b). Is mounted, and drives the crawler 5 to rotate. A blade 6 and a blade cylinder 7 for raising and lowering the blade are attached to the lower traveling body 1. The upper revolving unit 2 is mounted on the lower traveling unit 1 so as to be revolvable, and the work front 3 is supported by the front part of the upper revolving unit 2 so as to be vertically movable. The work front 3 is of an offset type, and includes a boom 3a, an offset 3b, an arm 3c, and a bucket 3d.

FIG. 4 shows an example of a conventional hydraulic circuit device of a hydraulic excavator with blades.

The engine 9 drives variable displacement hydraulic pumps 10a and 10b for work front, turning, and traveling, a fixed displacement hydraulic pump 11 for blades, and a fixed displacement hydraulic pump 12 for pilot. The traveling motors 4a and 4b are driven by variable displacement hydraulic pumps 10a and 10b.
Directional control valves 13, 14
It is switched by the pilot pressure RR or RF, LR or LF generated by the operation of the pilot operation valves 15 and 16. Also, the directional control valves 17, 18, 19, 20, 21, 22, 22
Numerals 23 denote a front actuator (not shown), a swing for driving a swing motor, a first arm, a first boom, an offset, a bucket, a second boom, and a second arm. , 14 together with the main valve device 100.

In the main valve device 100, the directional control valves 13, 14, 17 to 23 are directional control valves 13, 21 to 21 connected in series to the center bypass line 24, respectively.
23 and directional control valves 17-20, 14 connected in series to the center bypass line 25. The directional control valves 13, 21-23 are connected to the hydraulic pump 10a by the hydraulic oil supply line 26 and the center bypass line. The directional control valves 17 to 20, 14 are connected to the hydraulic pump 10b via the pressure oil supply line 27 and the center bypass line 2 through the line 24.
5 are connected. The direction control valve 14 is also connected to the hydraulic pump 10 a via a communication line 28 connected to the pressure oil supply line 26, and a traveling communication valve 29 is provided in the communication line 28. Pressure oil supply lines 26, 27
Is connected to a relief valve 30 as a safety valve.

Further, the pressure receiving portion of the traveling communication valve 29 is connected to the fixed displacement hydraulic pump 12 for pilot through a signal line 31, a throttle 32 and a pilot line 33, and a control line 34 is connected from the signal line 31 to the control line 34. The control line 34 branches off and passes through the directional control valves 17, 18, 19, 20, 21, 22, 23 to the tank.

The directional control valves 17, 18, 19, 20, 2
When one of 1, 2, 23 is operated, the control line 34
Is reduced, the pilot pressure in the signal line 31 increases, and the traveling communication valve 29 is switched. Thus, the pressure oil from the variable displacement hydraulic pump 10a is supplied to the left and right traveling motors 4a and 4b in parallel, so that traveling straightness is ensured at the time of a front or turning operation and a combined operation of the traveling operation.

The blade cylinder 7 is driven by a fixed displacement hydraulic pump 11 for the blade via a direction control valve 40 incorporated in the valve device 101 for the blade. The direction control valve 40 is connected to the hydraulic pump 11 via a pressure oil supply line 41, and the pressure oil supply line 41 is further connected to a center bypass line 42 penetrating the direction control valve 40. The downstream side is connected to the tank. A relief valve 43 as a safety valve is further connected to the pressure oil supply pipe 41, and overload relief valves 44 a and 44 b and replenishment check valves 45 a and 45 b are connected to the blade cylinder side of the direction control valve 40. I have.

When the directional control valve 40 is operated, the center bypass line 42 is throttled, and the hydraulic oil from the hydraulic pump 11 is supplied to the blade cylinder 7, and the blade cylinder 7
Expands and contracts, and the blade 6 shown in FIG.

As another prior art of a hydraulic drive system for a hydraulic excavator with a blade, there is JP-A-59-8841. In this prior art, the downstream side of a center bypass line passing through a blade directional control valve is connected to the upstream side of a center bypass line of a boom directional control valve, and the hydraulic oil for a blade hydraulic pump is connected to the boom directional control valve. It is possible to join.

[0012]

In the conventional hydraulic drive system shown in FIG. 4, the fixed displacement hydraulic pump 11 for blades uses the blades 6 infrequently, so that most of the operating time wastefully consumes power. .

In the hydraulic drive device described in Japanese Patent Application Laid-Open No. 59-8841, the hydraulic oil of the blade hydraulic pump can be joined to the boom directional control valve, so that the blade hydraulic pump can be effectively used when the blade is not used. Can be achieved.

In recent years, the need for increasing the traveling speed of hydraulic excavators has been increasing year by year, and there is a demand for increasing the traveling speed even slightly. JP-A-59-8841
The hydraulic drive described in the above publication does not meet the need for increasing the traveling speed, and cannot increase the traveling speed. Also, when increasing the traveling speed, 2
If they are not evenly joined to the two traveling motors, the traveling straightness is impaired.

An object of the present invention is to provide a hydraulic circuit device of a construction machine capable of effectively utilizing a hydraulic pump for an additional attachment and increasing a traveling speed without impairing straight traveling performance.

[0016]

[Means for Solving the Problems]

(1) In order to achieve the above object, the present invention provides at least one variable displacement hydraulic pump for front, turning and running, a plurality of actuators including a left and right running motor, and a plurality of including a directional control valve for the left and right running motor. A valve device comprising a directional control valve and a fixed displacement hydraulic pump for an additional attachment, an additional attachment actuator having an additional attachment actuator and a directional control valve, and a hydraulic circuit device for a construction machine, wherein: A synchronous shunt valve connected to a valve device for equally diverting the discharge flow rate of the fixed displacement hydraulic pump; And a link for switching the speed increasing control valve for the left and right traveling motor in conjunction with the direction control valve for the left and right traveling motor. Shall and an operating unit.

In the present invention constructed as described above, when the direction control valve for the left and right traveling motor is operated, the speed increasing control valve for the left and right traveling motor is switched by the interlocking operation means, and the hydraulic oil from the fixed displacement hydraulic pump is switched. Is guided to the left and right traveling motors via the synchronous shunt valve. For this reason, since the flow rate of the fixed displacement hydraulic pump is added to the amount of oil for driving the left and right traveling motors in addition to the conventional variable displacement hydraulic pump, the traveling speed increases as compared with the conventional case.

Further, the pressure oil from the fixed displacement hydraulic pump is divided by the synchronous diverting valve at every shunt ratio irrespective of the magnitude of the load. Nature is secured.

(2) In the above (1), preferably,
A conduit for guiding pressure oil from the speed increasing control valve to the left and right traveling motor is connected to a conduit between the directional control valve for the left and right traveling motor and the left and right traveling motor.

As a result, the present invention can be applied to the conventional hydraulic circuit device without making any change to the main valve device, so that the existing hydraulic circuit device can be driven by simple retrofitting if necessary. Speed up.

(3) In the above (1), preferably, the additional attachment valve device is configured to control a discharge flow rate from the fixed displacement hydraulic pump to a tank when the additional attachment directional control valve is at a neutral position. And a bypass line which is throttled when the additional attachment directional control valve is switched from the neutral position, and the synchronous shunt valve is connected downstream of the bypass line.

By connecting the synchronous diverting valve downstream of the bypass line in this way, when both the directional control valve for additional attachment and the speed-up control valve are operated, the directional control valve for additional attachment has priority. Is supplied with hydraulic oil from the fixed displacement hydraulic pump, and does not affect the operation of the additional attachment actuator.

(4) Further, in the above (1), preferably, the interlocking operation means transmits a signal from an operation valve for controlling each of the direction control valves for the left and right traveling motors to a speed increase for the left and right traveling motors. This is a means for leading to a control valve.

Thus, the speed increase control valve is switched in conjunction with the direction control valve for the left and right traveling motor. (5) In the above (1), preferably, the additional attachment is a blade for discharging earth.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. In these embodiments, a hydraulic excavator with a blade is taken as an example of a construction machine.

FIG. 1 is a diagram showing a hydraulic circuit device according to a first embodiment of the present invention. In the figure, parts that are the same as those of the conventional hydraulic circuit device shown in FIG. 4 are given the same reference numerals, and descriptions thereof are omitted.

In FIG. 1, the hydraulic circuit device of the present embodiment has a configuration in which a synchronous shunt valve 50 and speed-up control valves 51 and 52 for right and left traveling are added to the conventional hydraulic circuit device shown in FIG. ing. Further, in the blade valve device 110, the downstream of the center bypass line 53 penetrating the directional control valve 40 is not connected to the tank unlike the related art, and is connected to the synchronous diverting valve 50 via the pipeline 54. I have. The synchronous shunt valve 50 is connected to speed increasing control valves 51 and 52 via lines 55 and 56, and the speed increasing control valve 51 is connected to a line 57.
a, 58a is connected to the traveling motor 4a, and the speed-up control valve 52 is connected to the traveling motor 4b via lines 57b, 58b.
It is connected to the. Pipes 57a and 58a are directional control valves 1
The pipes 59a, 60a are connected between the directional control valve 14 and the travel motor 4b, and the pipes 57b, 58b are connected to the pipes 59b, 60b between the directional control valve 14 and the travel motor 4b.

The synchronous shunt valve 50 itself is well-known and has a function of equalizing and dividing the flow rate of the inflowing pressure oil regardless of the downstream resistance difference, whereby the pressure oil from the fixed displacement hydraulic pump 11 is supplied to the load. Regardless of the size, the flow is divided every 1/2.

Further, a pilot operation valve 1 for right and left traveling.
Pilot pressure RR or RF, LR or LF generated from 5, 16
Are output to the pipes 61, 62 and 63, 64 and guided to the pressure receiving portions of the directional control valves 13, 14, while the pipes 65, 66, 67, 68 are connected to the pipes 61, 62, 63, 64. And the pilot pressure RR or RF, LR or LF
The pressure increase control valves 51, 52 are also guided to the pressure receiving sections via 5, 66, 67, 68, and are switched in conjunction with the direction control valves 13, 14.

In this embodiment constructed as described above, when the pilot operation valves 15 and 16 for left and right traveling are not operated, the speed-up control valves 51 and 52 are in the illustrated neutral position,
Pipes 55 and 56 communicate with the tank. Therefore, when the direction control valve 40 for the blade is not operated, the pressure oil discharged from the hydraulic pump 11 passes through the center bypass line 53, the pipe 54, the synchronous diverting valve 50, and the pipes 55 and 56, and increases. It passes through the speed control valves 51 and 52 and is returned to the tank.

When the blade directional control valve 40 is operated, the center bypass line 53 is narrowed, and pressure oil from the hydraulic pump 11 is supplied to the blade cylinder 7 as in the conventional case.
Is moved up and down.

Pilot operation valves 15 and 16 for left and right running
Is operated, the speed-up control valves 51 and 52 become the directional control valve 1
Switched from the neutral position shown in conjunction with 3, 14
Pipes 55 and 56 are pipes 57a or 58a, 57b or 5
8b. Therefore, the pressure oil diverted by the synchronous diverter valve 50 can be supplied to the traveling motors 4a and 4b. When the directional control valve 40 for the blade is not operated, the pressure oil discharged from the hydraulic pump 11 is synchronized. The flow is divided equally by the flow dividing valve 50 and supplied to the traveling motors 4a and 4b. For this reason, the flow rate of the fixed displacement hydraulic pump 11 is added to the amount of oil for driving the traveling motors 4a and 4b in addition to the conventional variable displacement hydraulic pumps 10a and 10b.
The running speed increases compared to the conventional case.

When the synchronous shunt valve 50 is not provided, the pressure oil flows to the lower resistance due to the running resistance of the left and right running motors 4a and 4b, so that the straightness of the vehicle body cannot be ensured. By providing the synchronous diverting valve 50, the pressure oil from the fixed displacement hydraulic pump 11 allows the diverting ratio of 1/2 to be independent of the magnitude of the load.
The flow is diverted every time, and the straight traveling performance is secured.

When both the blade directional control valve 40 and the speed increasing control valves 51 and 52 are operated, the synchronous shunt valve 50 is connected to the downstream side of the center bypass line 53. The pressure oil from the hydraulic pump 11 is preferentially supplied to the control valve 40 and does not affect the operation of the blade cylinder 7 at all.

Also, as can be seen from a comparison with the conventional hydraulic circuit device shown in FIG. 4, in this embodiment, the center bypass line 53 is connected to the line 5 by the blade valve device 110.
No change was made to the main valve device 100 except for changing the connection to the connection No. 4. Further, the blade valve device 110
Can be changed simply by closing the portion connected to the tank on the downstream side of the conventional center bypass line 42 with a plug and connecting the pipe 54. The running speed can be increased by simply retrofitting the existing hydraulic circuit device if necessary.

A second embodiment of the present invention will be described with reference to FIG. In the figure, parts that are the same as the parts shown in FIG. 1 are given the same reference numerals. In the first embodiment, an open center type (center bypass type) is used as a direction control valve for a blade. However, in the present embodiment, a direction control valve for a closed center type blade is used.

In FIG. 2, reference numeral 110A denotes a blade valve device used in the present embodiment.
Is a closed center type directional control valve 40A for blades
A bypass pipe 70 branched from the pressure oil supply pipe 41 on the upstream side of the direction control valve 40A, and an auxiliary variable throttle valve 71 provided in the bypass pipe 70.
The synchronous shunt valve 50 is connected downstream of the auxiliary variable throttle valve 71.

A pilot operation valve 72 for blades is provided, and pilot pressures BU and BD generated by the pilot operation valve 72 are output to pipe lines 73 and 74 and guided to a pressure receiving portion of the direction control valve 40a. Further, a shuttle valve 77 is connected to the pipes 73 and 74 via pipes 75 and 76,
A pipe 78 is further connected to the shuttle valve 77, and the pilot pressure BU or BD generated by the pilot operation valve 72 is applied to the pressure receiving portion of the auxiliary variable throttle valve 71 via the pipe 75 or 76, the shuttle valve 77, and the pipe 78. Is also led.

The auxiliary variable throttle valve 71 is in the fully open position shown when the pilot operation valve 72 is at the neutral position, and when the pilot pressure BU or BD is at the tank pressure. (Pilot pressure BU
Or the level of the BD), the opening area is reduced (closed), and when the pilot operation valve 72 is fully operated, it is fully closed. As a result, the bypass line 70 performs the same function as the center bypass line 53 of the blade valve device 110 in the first embodiment.

The other structure is the same as that of the first embodiment.

In this embodiment constructed as described above, when the direction control valve 40A for the blade is not operated, the auxiliary variable throttle valve 71 is fully opened and the hydraulic pump 11
Is supplied to the flow dividing valve 50. For this reason, if the pilot operation valves 15 and 16 for left and right traveling are operated, the pressure oil diverted by the synchronous diverting valve 50 is supplied to the traveling motors 4a and 4b, and the traveling speed is reduced, as in the first embodiment. Speed up.

The synchronous shunt valve 50 is connected to the auxiliary variable throttle valve 7.
1, when both the blade directional control valve 40A and the speed-up control valves 51 and 52 (see FIG. 1) are operated, the hydraulic pump is given priority over the blade directional control valve 40A. The pressure oil from 11 is supplied and has no effect on the operation of the blade cylinder 7.

In the above embodiment, the case where the present invention is applied to a hydraulic circuit device of a hydraulic shovel provided with a blade as an additional attachment has been described. However, if the additional attachment uses a dedicated hydraulic pump, an additional attachment other than the blade is used. The present invention is similarly applicable to a hydraulic circuit device of a construction machine having an attachment, and a similar effect is obtained.

[0044]

According to the present invention, the following effects can be obtained.

(1) It is possible to effectively use the pressure oil of the hydraulic pump for the additional attachment, which conventionally wastes power for most of the operation time.

(2) The traveling speed can be increased without increasing the capacity of the variable displacement hydraulic pump and without impairing the straight traveling performance.

(3) If necessary, the running speed can be increased by simple retrofitting.

[Brief description of the drawings]

FIG. 1 is a diagram showing a hydraulic circuit device of a hydraulic shovel with blades according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a main part of a hydraulic circuit device of a hydraulic shovel with blades according to a second embodiment of the present invention.

FIG. 3 is an overall view of a hydraulic excavator with a blade.

FIG. 4 is a diagram showing a hydraulic circuit device of a conventional hydraulic shovel with blades.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lower traveling body 2 Upper revolving superstructure 3 Work front 3a Boom 3b Offset 3c Arm 3d Bucket 4a, 4b Traveling motor 5 Crawler 6 Blade 7 Blade cylinder 9 Engine 10a, 10b Variable displacement hydraulic pump 11 Fixed displacement hydraulic pump (for blade) 12 Fixed displacement hydraulic pump (for pilot operation) 13 Direction control valve (for traveling motor) 14 Direction control valve (for traveling motor) 15 Traveling pilot operation valve (right side) 16 Traveling pilot operation valve (left side) 17 Direction control valve ( 18 Direction control valve (for arm) 19 Direction control valve (for boom) 20 Direction control valve (for offset) 21 Direction control valve (for bucket) 22 Direction control valve (for boom) 23 Direction control valve (for arm) ) 24,25 Center bypass line 26,27 Pressure oil supply line Reference Signs List 8 bypass line 29 traveling communication valve 30 relief valve 31 signal line 32 fixed throttle 33 pilot line 34 control line 40 directional control valve (for blade) 41 pressure oil supply line 50 synchronous shunt valve 51, 52 speed-up control Valve 53 Center bypass line 54, 55, 56 Pipe 57a, 57b to 60a, 60b Pipe 61 to 68 Pipe 100 Main valve device 110 Valve device for blade

Claims (5)

[Claims] 1. A valve device comprising at least one variable displacement hydraulic pump for front, turning and running, a plurality of actuators including left and right running motors, and a plurality of directional control valves including directional control valves for left and right running motors, A hydraulic circuit device for a construction machine comprising a fixed displacement hydraulic pump for an additional attachment, an additional attachment actuator having an additional attachment actuator, and a directional control valve, the fixed displacement hydraulic device being connected to the additional attachment valve device. A synchronous shunt valve that equally divides the discharge flow rate of the pump; a speed increasing control valve for the left and right traveling motors that guides the pressure oil divided by the synchronous diverting valve to the left and right traveling motors; Interlocking operation means for switching the speed-up control valve for the left and right traveling motor in conjunction with the valve. The hydraulic circuit system for a construction machine according to. 2. A hydraulic circuit device for a construction machine according to claim 1, wherein a conduit for guiding pressure oil from said speed-increasing control valve to said left and right traveling motor includes a direction control valve for said left and right traveling motor and a left and right traveling motor. A hydraulic circuit device for a construction machine, wherein the hydraulic circuit device is connected to a pipeline between the hydraulic circuit and the construction machine. 3. The hydraulic circuit device for a construction machine according to claim 1, wherein the additional attachment valve device controls a discharge flow rate from the fixed displacement hydraulic pump when the additional attachment directional control valve is at a neutral position. Leading to the tank,
A hydraulic circuit device for a construction machine, comprising: a bypass pipe which is throttled when the directional control valve for an additional attachment is switched from a neutral position, and wherein the synchronous shunt valve is connected downstream of the bypass pipe. 4. The hydraulic circuit device for a construction machine according to claim 1, wherein said interlocking operation means receives a signal from an operation valve for controlling a direction control valve for each of said left and right traveling motors. A hydraulic circuit device for a construction machine, wherein the hydraulic circuit device is a means for leading to a speed control valve. 5. The hydraulic circuit device for a construction machine according to claim 1, wherein said additional attachment is a blade for discharging earth.