JP2776868B2 - Hydraulic flow control device for construction machinery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a hydraulic flow control device for a construction machine comprising a pair of compound control valves and a pair of variable displacement pumps. The present invention relates to an opening / closing control device of a communication valve for hydraulic oil merging provided between both composite control valves and a discharge control device of a variable displacement pump.

[Conventional technology]

As shown in FIG. 4, a hydraulic device of this type of conventional construction machine generally has two actuators 12 each.
a, 12b and a pair of composite control valves 10, 30 having directional control valves 14a, 14b and 34a, 34b for operating the 32a, 32b, and a pair of variable valves for supplying pressure oil to each of these composite control valves 10, 30 It consists of capacity pumps 16,36. The actuator 12
a, 12b, 32a, and 32b are usually used for turning, arm, boom, and bucket, respectively. The directional switching valves 14a, 14
b, 34a, 34b respectively comprise pressure compensating valves 18a, 18b, 38a, 38b, and control signal generators 20a, 20b, 40a, 40b respectively.
Is controlled by The two control valves 10 and 30 are mutually connected by a communication valve 42, and the communication valve 42
Is opened and closed by the control signal generators 20b and 40a.

Therefore, in the hydraulic device having such a configuration, each of the actuators 12a, 12b, 32a, and 32b has a control signal generator 2
0a, 20b, 40a, 40b, and in this case, furthermore, in this case, the actuators 12b,
At the time of operation of 32a, the communication valve 42 is communicated by operation of the control signal generators 20b, 40a, and the discharge pressure oil of both pumps 16, 36 is supplied to the actuators 12b, 32a in a combined manner. Therefore, there is an advantage that the actuators 12b and 32a requiring a large capacity, that is, the actuators for the arm and the boom can be operated at a high speed as required.

[Problems to be solved by the invention]

However, the advantage of the conventional hydraulic device described above is achieved only when one of the actuators for the arm and the boom is operated alone. Had the following disadvantages. That is, in the conventional hydraulic device, when the arm and boom actuators are simultaneously operated, the discharge pressure oils of both pumps join via the communication valve and simultaneously act on both actuators.
The merged discharge pressure oil is supplied only to the actuator having the lower load pressure in both actuators.
Therefore, there is a problem that the actuator with the higher load pressure is not operated. This hinders the operability and safety of the construction machine.

Therefore, an object of the present invention is to allow both actuators to be driven at the same time even when the actuators on the large flow rate side in both composite control valves are simultaneously operated,
It is still another object of the present invention to provide a hydraulic flow control device for a construction machine in which a combined flow rate of discharge pressure oil of both pumps can be arbitrarily set.

[Means for solving the problem]

In order to achieve the above object, a hydraulic flow control device for a construction machine according to the present invention includes a pair of composite control valves each having at least two directional control valves for operating an actuator, and a combination of these composite control valves. A pair of variable displacement pumps respectively supplying pressure oil to each, a plurality of control signal generators respectively controlling the operation amount of the direction switching valve, and a communication valve for mutually communicating between the pair of composite control valves; In the hydraulic flow rate control device, the composite control valve is a closed center type, the variable displacement pump is a load sensitive control type, and a flow regulating valve is provided between the composite control valve and the load sensitive control type variable displacement pump. The communication valve is opened and closed by a control signal and / or a control signal amount of the control signal generation device, and an opening degree of the flow control valve is controlled by a control signal amount of the control signal generation device. And the pressure before and after the flow control valve is applied to the control unit of the load-sensitive control type variable displacement pump.

In this case, when the control signals of the directional control valves in the two control valves are applied opposite to each other, and the signal amounts of the control signals are substantially equal or do not act together, the communication valve is connected to the two control valves. A block is formed between the control valves or a throttle is communicated, and when both control signals have different signal amounts or only one of the control signals is acting, the two control valves are configured to communicate with each other.

Further, by operating the control signal generating device for the predetermined specific directional control valve, the communication valve communicates between the two composite control valves and is connected to the composite control valve not including the specific directional control valve. The load-sensitive control type variable displacement pump is configured so that its pump discharge flow rate is regulated to an arbitrary flow rate equal to or less than the pump maximum discharge flow rate.

[Action]

In order to simultaneously operate the actuators on the large flow rate side of each of the two control valves, for example, the actuators for the arm and the boom, at the same time at a high speed, the respective control signal generators are operated to the maximum amount so that the discharge pressure oils of both the pumps are combined. In this case, the amount of signal applied opposite to the communication valve becomes equal, so that the communication valve is blocked. For this reason, the discharge pressure oils of both pumps are not merged, and the discharge flow rates of the respective pumps are supplied to both actuators. Accordingly, the two actuators are driven independently of each other at approximately half the speed of the single operation but without being stopped. On the other hand, when the discharge pressure oil of the other pump is merged to increase the speed of a small-capacity actuator such as a bucket, a signal amount of a predetermined ratio of the control signal amount of the actuator is supplied to the flow control valve of the pump. Output
As a result, the discharge flow rate of the pump is increased by a predetermined amount, and the increased amount of pressure oil is supplied to the bucket actuator via the communication valve. Therefore, the bucket actuator is efficiently driven at the controlled high speed.

〔Example〕

Next, an embodiment of a hydraulic flow control device for a construction machine according to the present invention will be described in detail with reference to the accompanying drawings. For convenience of description, the same components as those of the conventional configuration shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 1, the hydraulic flow control device for a construction machine according to the present invention has two actuators 12a and 12b, respectively.
And directional valves 14a, 14b and 34a, which operate 32a, 32b.
34b, and a pair of variable displacement pumps 5 for supplying pressurized oil to each of the composite control valves 50, 52.
The actuators 12a, 12b, 32
a and 32b are usually provided for turning, arm, boom, and bucket, respectively. The directional control valves 14a, 14b, 34a, 34
b comprises pressure compensating valves 18a, 18b, 38a, 38b, respectively, and is controlled by control signal generators 20a, 20b, 40a, 40b, respectively. A communication valve 58 is provided between the combined control valves 50 and 52.
Are communicated with each other.

However, in the hydraulic flow control device of the present invention, the composite control valves 50 and 52 are of a closed center type, and the variable displacement pumps 54 and 56 are of a load sensitive control type. Each of the control signal generating devices 20a, 20a, of the load-sensitive control type variable displacement pumps 54, 56 (hereinafter simply referred to as pumps) and the closed center type composite control valves 50, 52 (hereinafter simply referred to as composite control valves).
Between 20b and 40a, 40b, respectively, the control arithmetic unit 6
Flow control valves 64, 66 are provided via 0,62. The control arithmetic unit 60 is an actuator in the composite control valve 50.
Output control signal amount of control signal generators 20a and 20b for 12a and 12b and actuator 32 which needs to be merged in compound control valve 52
When the total output control signal amount, which is the sum of the output control signal amounts of the control signal generators 40a and 40b for a and 32b, exceeds the maximum discharge flow rate of the pump 54, the output control signal corresponding to this maximum discharge amount The amount is output to the flow control valve 64. Control arithmetic unit 62
Are control signal generators 40a, 4 for the actuators 32a, 32b.
Actuator 12a that needs to merge with the output control signal amount of 0b,
When the total output control signal amount, which is the sum of the output control signal amounts of the control signal generators 20a and 20b for 12b, exceeds the maximum discharge flow rate of the pump 56, the output control signal amount corresponding to this maximum discharge amount is calculated. Is output to the flow control valve 66. Then, the pressures before and after the flow regulating valves 64 and 66, the opening degrees of which are adjusted by the total output control signal amount, are applied to the control units of the pumps 54 and 56, whereby the pump discharge flow rate becomes a predetermined flow rate. Is set to

The communication valve 58 is formed in a block type, and a control signal from the control signal generator 20b for the actuator 12b is applied to one end of the communication valve 58, and a control signal generator 40a, 40b for the actuators 32a, 32b is applied to the other end. The larger signal amount of the control signals is applied via the control device 68. Incidentally, the communication valve may be formed in a throttle-type communication valve 70 as shown in FIG. This communication valve 58 or 70 blocks between the two composite control valves 50 and 52 when the signal amounts of the control signals applied to both ends thereof are substantially equal or do not act together. Alternatively, when the signal amounts of the two control signals are different or only one of the control signals is acting, the two control units 50 and 52 are communicated with each other.

Next, the operation of the hydraulic flow rate control device of the present invention having such a configuration will be described.

First, when driving the arm actuator 12b or the boom actuator 32a on the large flow rate side in each of the combined control valves 50 and 52 alone, for example, when driving only the boom actuator 32a, this actuator 3
The control signal generator 40a for 2a is operated. Then, the direction switching valve 34a is switched by the control signal output from the control signal generator 40a, and the flow rate command value set by the control arithmetic unit 62 in accordance with the signal amount of the control signal is changed to the flow rate adjusting valve. A predetermined amount of pressure oil applied to the pump 66 and discharged from the pump 56 is supplied to the actuator 32a. Further, a communication valve 58 is communicated by the control signal, and a flow rate command value set by the control arithmetic unit 60 in accordance with the signal amount is applied to the flow rate adjustment valve 64, and a predetermined amount discharged from the pump 54 Is combined with the pressure oil from the pump 56 and supplied to the actuator 32a. In this way, the actuator 32a is driven at a predetermined speed by the combined flow rate of the pressure oil from the two pumps 54 and 56. The arm actuator 12b is also driven independently in the same manner.

Next, in order to drive both actuators 12b and 32a with a large flow rate simultaneously and at a high speed, respective control signal generators 20b and 40a are used.
When a is operated to the maximum amount, the pumps 54 and 56 are set to the maximum discharge flow rate via the respective control operation devices 60 and 62 and the flow control valves 64 and 66. However, in this case, the communication valve 58 receives the control signal amount of the same magnitude at both ends thereof, so that the communication valve 58 is in the block position, and the communication between the two composite control valves 50 and 52 is shut off. Therefore, both actuators 12b, 32
a is individually and independently driven by the respective maximum discharge amounts of the respective pumps 54 and 56. As described above, in the hydraulic flow rate control device of the present invention, both the large capacity actuators 12b and 32a
, At the same time, the driving speed is almost half that of the single operation, but there is no inconvenience such as stopping the operation of the actuator on the side with a large load as in the conventional device. In this case,
When the control operation amount of either one of the control signal generators 20b, 40a is reduced, that is, for example, when the operation lever of the device 40a is slightly returned to the neutral direction, the communication valve 58 causes the two combined control valves 50, A part of the discharge flow rate of the pump 56 is supplied to the actuator 12b by communicating between the two. Therefore,
The speed of actuator 32a is reduced somewhat, while the speed of actuator 12b is increased by this reduced speed.
Similarly, when the control operation amount of the device 20b is reduced, the speed of the actuator 12b is reduced somewhat, and the speed of the actuator 32a is increased by the reduced speed. In this case, since the drive load of the actuator is usually higher in the boom actuator 32a, the pump discharge pressure is set to be higher in the pump 56, but a check is provided in the communication valves 58 and 70. Therefore, the pump discharge pressure oil does not flow backward. That is, by the communication of the communication valve,
There is no inconvenience that the discharge pressure oil from the pump 56 is reversely supplied to the actuator 12b and the speed of the actuator 12b is increased contrary to the control operation.

Next, when the drive speed of the bucket actuator 32 of the small flow rate in the composite control valve 52 is increased to, for example, 1.5 speed by combining the discharge pressure oil of the other pump 54, the control signal generation device 40b The control signal amount is reduced to half by the control arithmetic unit 60 and then output to the flow regulating valve 64. This increases the discharge flow rate of the pump 54 corresponding to 0.5 speed, and the increased discharge pressure oil is combined and supplied to the actuator 32b through the communication valve 58. Therefore, actuator 3
2b is driven at the control operation value of 1.5 speed. As described above, in the hydraulic flow rate control device of the present invention, the discharge flow rate of the merged pump can be set arbitrarily within the range of the maximum discharge flow rate of this pump. Therefore, the operation accuracy of the actuator and the operation efficiency of the device can be improved.

The pressure compensating valves 18a, 18b, 38a, 38b may be omitted, and the embodiment shown in FIG. 3 shows such an embodiment.

Although the present invention has been described with reference to the preferred embodiment, it is needless to say that the present invention can be subjected to many design changes without departing from the spirit thereof.

〔The invention's effect〕

As described above, the hydraulic flow control device for a construction machine according to the present invention includes a pair of composite control valves each having at least two directional control valves for operating an actuator, and each of these composite control valves. It comprises a pair of variable displacement pumps for respectively supplying pressure oil, a plurality of control signal generators for respectively controlling the operation amounts of the direction switching valves, and a communication valve for mutually communicating between the pair of composite control valves. In the hydraulic flow rate control device, the composite control valve is a closed center type, the variable displacement pump is a load sensitive control type, and a flow regulating valve is provided between the composite control valve and the load sensitive control type variable displacement pump, The communication valve is opened / closed by a control signal and / or a control signal amount of the control signal generator, and an opening of the flow regulating valve is adjusted by a control signal amount of the control signal generator. And the pressures before and after the flow control valve are applied to the control section of the load-sensitive control type variable displacement pump. Can be simultaneously driven irrespective of the load when the maximum speed-up operation is simultaneously performed. When the required combined flow does not reach the maximum flow rate of the pump discharge flow, the combined flow can be arbitrarily set to a predetermined required amount.

Therefore, the operability, safety, and operation efficiency of the actuator can be improved.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing one embodiment of a hydraulic flow control device for construction equipment according to the present invention, and FIG. 2 is a hydraulic symbol showing another embodiment of a communication valve in the hydraulic flow control device shown in FIG. FIG. 3 is a hydraulic circuit diagram showing another embodiment of the hydraulic flow control device for construction machines according to the present invention, and FIG. 4 is a hydraulic circuit diagram showing a conventional hydraulic flow control device for construction machines. 12a, 12b, 32a, 32b ... Actuators 14a, 14b, 34a, 34b ... Directional switching valves 18a, 18b, 38a, 38b ... Pressure compensating valves 20a, 20b, 40a, 40b ... Control signal generators 50, 52 … Combined control valves 54,56… Load-sensitive control type variable displacement pumps 58,70… Communication valves, 60,62… Control computing devices 64,66… Flow control valves, 68… Control devices

Continued on the front page (72) Inventor Takashi Shinya 4-5676 Hibarigaoka, Zama City, Kanagawa Prefecture Inside the Sagami Plant of Toshiba Machine Co., Ltd. In-house (56) References JP-A-59-194105 (JP, A) JP-A-62-206125 (JP, A) (58) Fields studied (Int. Cl. ⁶ , DB name) F15B 11/02, 11/16 E02F 3/43

Claims (5)

(57) [Claims] A pair of compound control valves each having at least two directional valves for operating an actuator;
A pair of variable displacement pumps for supplying pressure oil to each of the composite control valves, a plurality of control signal generators for controlling the operation amounts of the directional control valves, respectively, and a mutual connection between the pair of composite control valves. A hydraulic flow control device comprising a communicating valve that communicates with the hydraulic control device, wherein the composite control valve is a closed center type, the variable displacement pump is a load-sensitive control type, and a valve between the composite control valve and the load-sensitive control type variable displacement pump. A flow control valve is provided, and the communication valve is opened and closed with a control signal and / or a control signal amount of the control signal generator, and an opening degree of the flow control valve is adjusted with a control signal amount of the control signal generator. A hydraulic flow control device for a construction machine, wherein pressures before and after a lever flow control valve are applied to a control unit of the load-sensitive control type variable displacement pump. 2. The communication valve according to claim 1, wherein the control signals of the directional control valves of the two control valves are applied to face each other, and when the signal amounts of the control signals are substantially equal or do not act together, The two control valves may be blocked or communicated via a throttle, and may communicate between the two control valves when both signal amounts of the control signals are different or only one of them is acting. The hydraulic flow rate control device for a construction machine according to claim 1, wherein 3. The communication valve communicates between the two composite control valves by operation of the control signal generating device for the predetermined specific directional control valve, and the composite control valve on the side not including the specific directional control valve is provided. 2. The hydraulic flow control device for a construction machine according to claim 1, wherein the load-responsive control type variable displacement pump connected to the pump is controlled so that the pump discharge flow rate is regulated to an arbitrary flow rate equal to or less than the pump maximum discharge flow rate. 4. The hydraulic flow control device for a construction machine according to claim 1, wherein the directional control valve of the composite control valve includes a pressure compensating valve. 5. The hydraulic flow control device for a construction machine according to claim 1, wherein the directional control valve of the composite control valve has no pressure compensating valve.