JPS63190903A - Automatic speed control circuit for hydraulic actuator - Google Patents

Abstract

PURPOSE:To improve operating efficiency as well as safety of the device in the caption by enabling the oil discharge of main pumps to be automatically increased/decreased in such a way as to become required quantity when a particular hydraulic actuator is operated. CONSTITUTION:In main pumps 1, 2 are provided flow control valves C, D for increasing/decreasing oil discharge of the main pumps 1, 2. The flow control valves C, D are connected to pilot pipes 30 through 33 via a solenoid switching valve 17 and shuttle valves 22, 23 which are operated by a switch 24 near a driver's seat. When a particular hydraulic actuator is operated, the switch 24 is turned on to switch the solenoid switching valve 17, so that a pilot pressure is applied on the flow control valves C, D. Therefore, oil discharge of the main pumps 1, 2 can be automatically increased/decreased as required so that the hydraulic actuator can be driven at the optimum speed, hence improving operating efficiency as well as enabling safe operation.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention is suitable for the work only when operating one or more hydraulic actuators among a plurality of actuators operated by discharge pressure oil of a variable displacement pump. This relates to a hydraulic circuit that automatically changes the amount of oil discharged depending on the speed.

Conventional technology The discharge pressure oil of a variable displacement pump is switched by a hydraulic switching valve group consisting of multiple hydraulic switching valves, and is supplied to hydraulic actuators such as hydraulic cylinders and hydraulic motors for various operations, and the combination of operations is used to achieve the desired purpose. construction machinery that performs work;
Traditionally, work machines have been dedicated machines equipped with hydraulic pumps, hydraulic actuator capacities, and hydraulic circuits so that the speed of the work equipment can be adjusted according to the work content, but in recent years this has changed. As work styles and needs change, we are improving the operating rate of machines and increasing economic efficiency by using one machine for multiple purposes and introducing machines with the same capacity and performance as dedicated machines. There is a growing tendency to

For example, by using the main body of a hydraulic excavator as it is and replacing the front attachment, a hydraulic excavator that was originally intended for excavation can be used for crane work, or by installing an attachment with a winch function and replacing the front attachment. The excavator itself is used as a hydraulic winch by using pressure oil.

In such a case, for example, considering the swing speed, the swing operation of the upper rotating structure in a hydraulic excavator requires starting and stopping the swing at least twice for one excavation and loading, and moreover, Since work efficiency cannot be improved unless the operation is completed in a short time, the design is such that a large amount of pressure oil is supplied to the hydraulic motor for swinging to increase the swinging speed. However, when a crane attachment is attached to the main body of this hydraulic excavator and the crane is operated at the same swing speed as the hydraulic excavator, the lifted load is subject to centrifugal force and swing inertia. Not only is it extremely difficult to determine the desired position, but it may also cause an unexpected accident.

In addition, when a hydraulic winch is attached to the end of the arm of a hydraulic excavator and the winch is operated using pressure oil for operating the packet of the hydraulic excavator, the hydraulic cylinder for operating the packet of the hydraulic excavator is generally not connected to the boom or Since only a small amount of pressure oil is supplied compared to the hydraulic cylinder for operating the arm, it has been difficult to increase the speed of the winch or increase the strength.

In order to deal with this, in the former case, a driver with specific skills is engaged in the operation, and in the latter case, in addition to making modifications to change the use of the machine, conventional technology , the driver operates the operating device each time,
A method has been used in which the speed of a hydraulic actuator is decreased or increased by adjusting the amount of pressure oil discharged from a variable displacement pump.

An example of this prior art will be explained with reference to a hydraulic system diagram in FIG. This diagram is a basic hydraulic system diagram of a roller-type hydraulic excavator, consisting of two main pumps and two hydraulic switching valve groups. be.

In the figure, 101 is a main pump, the discharge pressure oil of which flows into the hydraulic switching valve group A, and the boom first hydraulic switching valve 5.
Arm 2nd speed hydraulic switching valve6. Packet hydraulic switching valve 7
．． Either of the left travel hydraulic switching valves 8 is the pilot valve 10.
When the switch is made by operating the operating lever B, a hydraulic actuator (not shown) connected to the hydraulic switching valve through a conduit is operated. In addition, 102 is another main pump, and similarly to the above, the discharge pressure oil is supplied to the hydraulic switching valve group B.
The flow flows into the boom 2nd speed hydraulic switching valve 9 and the arm 1st speed hydraulic switching valve 10. The turning hydraulic switching valve 11 and the right travel hydraulic switching valve 12 operate the respective hydraulic actuators. 3 is a pilot pump, and its discharge pressure oil is maintained at a specified pressure by the action of a relief valve 14, passes through a pipe ill, and becomes a hydraulic pressure source for a plurality of pilot valves 108, By operating the operating lever, pilot pressure passes through a pilot pipe (not shown) to each hydraulic switching valve 5.
6. F, 8, 9, 10, 11. The oil flows in and out of pilot oil chambers 8, 9, 10, and 11, respectively, and switches the corresponding hydraulic pressure switching valves.

Further, a pipe line 112 branched from the pipe line 111 communicates with the electromagnetic switching valve 10f. This electromagnetic switching valve 107 is normally located at the A position due to the biasing force of the spring, and the internal oil passage leading to the pipe line 113 is closed. Switching to the port position, the internal oil passage is opened, and the outlet port is
At the position A, the pipe line 113 that communicated with the tank 40 communicates with the pilot oil chambers 104, 106 of the flow control valves σ, D' of the main pumps 101, 102.

When using a hydraulic excavator having a hydraulic circuit configured as described above with the original excavator attachment, do you perform excavation work by operating any operating lever of the pilot valve 108 while keeping the switch 109 open? If you attach a crane attachment as a front attachment with the hydraulic circuit in this state and operate, for example, the swing hydraulic switching valve 11, the upper swing structure of this machine will be strong and strong, just like a hydraulic excavator. It makes rapid turns, which is not only unsuitable for crane work, but also dangerous.

Therefore, when installing the crane attachment, the switch 109 is closed in advance and then the operation is started. That is, when the switch 109 is closed and the power source 110 or the electromagnetic switching valve 107 is energized, the electromagnetic switching valve is switched from the A position to the Open position, the pipes 112 and 113 are communicated, and the pilot pump 3 is The discharge pressure oil is supplied to pipe Ill, 112.
At the mouth of the electromagnetic switching valve 107, the oil passage passes through the pipe line 113,
The oil is guided to the pilot oil chambers 104 and 106 of the flow rate adjustment valves σ and D', and reduces the amount of oil discharged from the main pumps 101 and 102. Therefore, the amount of oil flowing into the hydraulic switching valve group B from the main pump 102 is small, and the amount of oil flowing into the hydraulic switching valve group B is small.
1, the amount of oil supplied to the turning hydraulic actuator is smaller than that when using a hydraulic excavator, and the turning speed is also limited, so lane work can be done safely.

In addition, the pilot oil chamber 10 in the flow rate adjustment valve σ, rf
3, 105 is a pilot oil chamber for power compensation, and the discharge pressure of the main pumps 101, 102, which changes depending on the magnitude of the load applied to each actuator, is controlled by the pipes 38, 105.
39, and when the discharge pressure increases, the amount of discharged oil is automatically limited so that the prime mover (not shown) for driving the pump does not become overloaded. When a signal pressure is applied to 106, the amount of oil discharged increases or decreases in accordance with this signal pressure, regardless of the discharge pressure of main pump 1.2.

FIG. 7 is a diagram showing the relationship between the discharge oil amount and discharge pressure of the main pumps 101 and 102 controlled by the flow rate adjustment valves σ and D''. When the discharge pressure is P or less, the maximum discharge is achieved. Although the oil amount is maintained at Q1.

Discharge pressure or P. As the pressure exceeds P1 and approaches the specified maximum pressure P1, the amount of discharged oil changes from Q to Q. decreases to.

Further, when the switch 109 is closed, even when the discharge pressure P is low, the maximum discharge oil amount becomes Q2, which is smaller than ql, and the above-mentioned turning speed also becomes slower.

Problem to be Solved by the Invention In order to control the speed of a hydraulic actuator to a speed other than its original performance, it is possible to increase or decrease the amount of oil discharged from the main pump by using an operation signal from the driver as described above. If you use this method, the amount of oil discharged by the main pump will be set to the amount of oil required for the hydraulic actuator whose speed you want to control, so even when that hydraulic actuator is not in use, the oil pressure switching of the main pump series described above will be performed. The speeds of other hydraulic actuators operated by the hydraulic switching valves belonging to the valve group are also controlled, resulting in decreased work efficiency and danger. In addition, it would be cumbersome to operate and increase or decrease the discharge amount of the main pump each time a predetermined hydraulic actuator is activated.
It may also cause incorrect operation.

Means for Solving the Problems In order to solve the above problems, the present invention has the following configuration. In other words, the main pump is equipped with a flow regulating valve that has a pilot oil chamber that increases or decreases the amount of oil discharged in response to signal pressure from the outside, in addition to power compensation. 2 of the hydraulic switching valves for the hydraulic actuator that belong to the inflowing hydraulic switching valve group and whose speed is to be controlled
A shuttle valve is provided that selects and takes out the pilot pressure on the high pressure side from among the pipes passing through the two operating pilot oil chambers, and c. A pipe that communicates the shuttle valve with the pilot oil chamber of the flow rate adjustment valve. In the middle of the process, the pipeline from the shuttle valve is normally closed by the biasing force of a built-in spring, the pipeline from the pilot oil chamber of the flow rate adjustment valve is communicated with the tank, and the shuttle is closed by an external electrical signal. An electromagnetic switching valve with a function to connect the valve to the pilot oil chamber of the flow rate adjustment valve will be installed, and a switch will be installed near the 21M transfer seat to allow easy switching of the electromagnetic switching valve.

When trying to operate the hydraulic actuator at a speed higher or lower than its original performance, for example, when changing the front attachment from a shovel attachment to a crane attachment and wanting to reduce only the swing speed, the driver's seat When a nearby switch is closed and an electric signal is supplied to the electromagnetic switching valve and a swing operation is started, pilot pressure is generated in either of the two operating pilot oil chambers of the swing hydraulic switching valve, so the pilot The pressure passes through the shuttle valve, the switching passage of the electromagnetic switching valve, and reaches the pilot oil chamber of the flow rate adjustment valve of the main pump as a signal pressure.

As a result, only during swing operation, the amount of oil discharged from the main pump is automatically reduced, and the amount of oil flowing into the hydraulic switching valve group to which the swing hydraulic switching valve belongs is reduced. The amount of oil flowing into the hydraulic actuator is small,
Turning speed is reduced.

Next, when the swing operation is stopped, the pilot oil chamber of the flow rate adjustment valve communicates with the tank via the switching passage of the electromagnetic switching valve, the shuttle valve, and the pilot valve for swing operation, and the pressure signal disappears, so the main pump The amount of oil discharged automatically returns to the original amount. At this time, if an operation other than a swing operation is performed, such as a boom activation operation, the pilot oil chamber of the flow rate adjustment valve remains connected to the tank, so the amount of oil discharged from the main pump will be reduced to its original performance. The operating speed of the boom hydraulic actuator remains unchanged.

When engaging in excavation work with the shovel attachment attached as a front attachment, if you leave the switch near the driver's seat open, the pilot oil chamber of the flow control valve will always be connected to the tank via the electromagnetic switching valve. communication,
Since no pressure signal is generated, the amount of oil discharged from the main pump remains at the original performance oil amount.

Embodiment An embodiment of the present invention will be described in detail with reference to FIG. Figure 1 shows
For the hydraulic circuit of crawler hydraulic excavators.

It is an electric/hydraulic circuit diagram in which the automatic speed control circuit of the present invention is provided, and as an example, a hydraulic switching valve 13 for a winch (not shown) is added to the hydraulic switching valve group A.

Only when these two hydraulic switching valves are operated together with the swing hydraulic switching valve 11 of the hydraulic switching valve group B, the amount of oil discharged from the main pump 1.2 that flows into the hydraulic switching valve group to which they belong is increased or decreased. It was designed to let you do so.

In the figure, 3 is a pilot pump that serves as a hydraulic pressure source for each operating system including pilot valves 15 and 16, and its discharge pressure oil is maintained at a constant pressure by the action of a relief valve 14, and is further branched into a pipe 26. Supply pressure oil to pipes 27, 28, 29, etc. The hydraulic switching valve group A is the boom first communication hydraulic switching valve 5. Arm 2nd speed hydraulic switching valve6. Packet hydraulic switching valve 7, left travel hydraulic switching valve 8. The hydraulic switching valve group B consists of a winch hydraulic switching valve 13, and the hydraulic switching valve group B includes a boom second speed hydraulic switching valve 9. Arm first speed hydraulic switching valve 10, swing hydraulic switching valve 11. Consists of a hydraulic switching valve 12 for right travel,
Each hydraulic switching valve is switched between forward and reverse by pilot pressure from a dedicated pilot valve (other than the winch pilot valve 15 and the swing pilot valve 16 are not shown).

The main pumps 1 and 2 are variable displacement pumps and have known flow rate adjustment valves C and D, and the flow rate adjustment valve C has a pilot oil chamber that increases or decreases the amount of oil discharged from the main pump 1 in response to signal pressure. 1B, 19, the flow rate adjustment valves have pilot oil chambers 20, 21 that increase or decrease the amount of oil discharged from the main pump 2 in response to signal pressure, and the pilot oil chambers 1B, 20
is the pilot oil chamber for power compensation, and is the main pump 1.
．． When the discharge pressure oil of No. 2 is guided through the pipes 38 and 39 and its pressure increases according to the load of the actuator to be operated,
To prevent the absorption horsepower of main pump 1.2 from exceeding the limit,
This enables so-called equal horsepower operation. In addition, the pilot oil chambers 19 and 21 are connected to the pilot pipes 36 and 37, regardless of the discharge pressure of the main pumps 1 and 2, and when a pressure signal is applied thereto, the amount of oil discharged from the main pumps 1 and 2 increases. In the example shown in Fig. 1, when a pressure signal is applied to the pilot oil chamber 19, the amount of oil discharged from the main pump 1, that is, the amount of oil flowing into the hydraulic switching valve group A increases, and the amount of oil flowing into the hydraulic switching valve group A increases. When a pressure signal is applied to the oil chamber 21, the amount of oil discharged from the main pump 2, that is, the amount of oil flowing into the hydraulic switching valve group B, is reduced.

Reference numerals 22 and 23 are shuttle valves, which are connected to pilot lines 30 and 31 from the pilot valve 15 that switch the winch hydraulic switching valve 13 and pilot lines 32 and 33 from the pilot valve 16 that switches the swing hydraulic switching valve 11, respectively. , the pilot pressure on the high pressure side is selectively taken out, taken out to pilot pipes 34 and 35, respectively, and led to the inlet port of the electromagnetic switching valve 17.

Then, when the electromagnetic switching valve 17 does not receive an electric signal at its receiving part, it is held in the A position by the biasing force of the spring, and at this time, the pilot oil chamber of the flow rate adjustment valves C and D is held. The pilot pipes 36 and 37 passing through the pipes 19 and 21 are both connected to the tank 40, and when an electric signal is applied to the receiver, the pilot pipes 34 and 36 are switched to the opening position, and the pilot pipes 34 and 36 are
It also has a function of communicating the pilot pipes 35 and 37.

In addition, 4, 4 in the figure is a relief valve, 40 is a tank,
24 is a switch that disconnects or disconnects the circuit between the receiving section of the electromagnetic switching valve 17 and the power source 25.

The operation of the present invention will be explained with reference to the embodiment diagrams of the present invention as described above.

First, when a machine having this electric/hydraulic circuit is equipped with a hydraulic excavator attachment, the switch 24 is left open. At this time, the electromagnetic switching valve 17 maintains the A position, and the pilot oil chambers 19 and 21 are communicated with the tank 40 through the pilot pipes 36 and 37, so the main pumps 1 and 2 are Performance of discharge oil amount,
That is, the main pump l has a discharge oil amount Q or Q++ in FIG. 2, and the main pump 2 has a discharge oil amount Q in FIG.
or the same <Q, and the flow flows into the hydraulic switching valve groups A and B, respectively, and the various hydraulic switching valves 5.6, 7, 8,
No matter which one of 9, 10, 11, and 12 is operated, work such as excavation can be performed at an operating speed suitable for operating each hydraulic actuator of the hydraulic excavator.

Next, when equipped with a crane attachment to enable high-speed operation when the winch is activated, and to reduce the rotation speed during the swing operation for the purpose of improving work efficiency and operability, the switch 24 is closed. Start operation.

Then, the electromagnetic switching valve 17 is switched from the A position to the Open position, and the pilot pipes 34 and 36 and 35 and 37 are brought into communication. At this time, if the pilot valve 15 is operated and pilot pressure is generated in the pilot pipe 30 or 31,
The winch hydraulic switching valve 13 is switched to the normal or reverse position, and either pilot pressure is transferred to the shuttle valve 2.
2. Pilot pipe 34° - Port position of the electromagnetic switching valve 17 Oil pipe flows into the pilot oil chamber 19 of the flow rate adjustment valve C through the pilot pipe 36, and the discharge amount of the main pump 1 is adjusted to the second level.
The amount is increased from Ql in the figure to Q4, and as a result, the winch hydraulic actuator connected to the winch hydraulic switching valve 13 operates faster.

In addition, the pilot valve 16 is operated, and the pilot pipe line 32
33, the swing hydraulic switching valve 11 is switched to the normal or reverse position, and either of the pilot pressures is applied to the shuttle valve 23.33. Pilot conduit 35. It flows into the pilot oil chamber 21 of the flow rate adjustment valve through the oil passage at the mouth position of the electromagnetic switching valve 17 and the pilot pipe 37, and changes the discharge oil amount of the main pump 2 from Ql to q3 in Fig. 3.
As a result, the operation of the swing hydraulic actuator connected to the swing hydraulic switching valve 11 is slow, and the swing speed is also slow.

In the above embodiment, the amount of oil supplied to the winch hydraulic actuator is increased from the standard oil amount to speed up the work speed.
Although it has been shown that the hydraulic actuator for swinging can be reduced in weight to ensure safe work, for example, when driving on flat ground, the hydraulic actuator for driving can be The above-mentioned shuttle can be used to increase the amount of oil supplied to the hydraulic actuator to increase the traveling speed, to improve the work efficiency of hydraulically driven specific work tools such as hydraulic hammers, vibrating pile drivers, etc., or to meet other needs. valve placement,
Can be applied in a wide range of ways by combining quantities.

FIG. 4 is a diagram showing a second embodiment of the present invention, in which a general-purpose electromagnetic switching valve 41, 41 is used instead of the electromagnetic switching valve 17 in pilot pipes 34 and 36 and pilot pipes 35 and 3.
7 and 7, respectively, and operation 1
Both operations are the same as in the first embodiment. In addition, Fig. 5 is a diagram of a third embodiment in which an electromagnetic switching valve is not used, where 42 is a pilot pressure type switching valve, 43 is a manual two-position selector valve installed near the driver's seat, and 44 is a pilot pipe line. This is a shuttle valve that selects and takes out the higher pilot pressure of either 34 or 35, and its outlet port is connected to the pilot oil chamber of the switching valve 42.

In this embodiment, when it is desired to increase or decrease the amount of oil discharged from the main pump 1 or 2 when only the hydraulic actuator for operation is operated, the switching valve 43 is set to the 2nd position and the original standard oil amount is maintained. When in use, the same effect as in the first embodiment can be obtained by setting it to the C position.

Effects of the Invention When using a construction machine in which the electric/hydraulic circuit according to the present invention is incorporated into the operation and control circuit of a hydraulic actuator, it is possible to operate a certain hydraulic actuator among the hydraulic actuators driven by the pressure oil discharged from the main pump. The amount of oil delivered by the main pump can be automatically increased or decreased from the original standard amount so that the amount of oil matches the speed required for the hydraulic actuator.
This allows the hydraulic actuator to be easily operated at the most appropriate speed without requiring special operations or special skills.

It is possible to improve work efficiency and perform safe and reliable work.

[Brief explanation of the drawing]

Figure 1 is an electric/hydraulic circuit diagram when an automatic speed control circuit for an actuator according to the present invention is added to the hydraulic circuit of a crawler type hydraulic excavator, and Figure 2 is a diagram of the main pump 1 in Figure 1. is a diagram showing the relationship between the discharge pressure P and the discharge oil amount Q of the main pump 2 in FIG.
The figure shows a second embodiment of the present invention, FIG. 5 is a main part hydraulic circuit diagram showing a third embodiment, FIG. 6 is an electric/hydraulic circuit diagram showing the prior art, and FIG. 7 is a diagram similar to that shown in FIG. main pump lot
, 102 is a diagram showing the characteristics of . 15.16 ...... Pilot valve 17
・・・・・・・・・・・・・・・ Solenoid switching valve 22.23
...... Shuttle valve 24 ......
・・・・・・・・・ Switch A, B ・・・・・・・
... Hydraulic switching valve group C1σ, D, D' ...
・ Flow rate adjustment valve 41 ・・・・・・・・・・・・・・・
Solenoid switching valve 42 ・・・・・・・・・・・・・・・ Switching valve 43 ・・・・・・・・・・・・・・・ Selector valve 4
4 ・・・・・・・・・・・・・・・ More than shuttle valve

Claims (1)

[Claims] Hydraulic actuation and hydraulic actuation in which a plurality of hydraulic actuators are actuated by the pressure oil supplied by switching the discharge pressure oil of one or more variable displacement main pumps using a pilot pressure-operated hydraulic switching valve to perform various operations on construction machinery. In the operating circuit, the main pump includes a flow rate adjustment valve having a pilot oil chamber with a function of increasing or decreasing the amount of discharged oil based on signal pressure from the outside, and a group of hydraulic switching valves into which the pressure oil discharged from the main pump flows. A shuttle valve that selects and extracts the higher pilot pressure from among the pipes leading to two pilot oil chambers for operating a hydraulic switching valve for a hydraulic actuator whose speed is to be controlled; Normally, the pipeline from the shuttle valve is closed by the biasing force of a built-in spring, and the pilot oil chamber of the flow rate regulating valve is connected to the pilot oil chamber of the flow regulating valve. A switching valve is provided which has the function of connecting the pipe line leading from the shuttle valve to the tank, and when a command signal is applied to the receiving part from the outside, communicating the pipe line leading to the outlet port of the shuttle valve and the pilot oil chamber of the flow rate adjustment valve. . An automatic speed control circuit for a hydraulic actuator of a construction machine, comprising a switch near the driver's seat for inputting a command signal to a receiving section of the switching valve.