JPS6322930A - Hydraulic circuit for construction machine - Google Patents

Abstract

PURPOSE:To enhance the diversion accuacy, operating performance, and economy of hydraulic circuit as well as to reduce the cost of the circuit by providing the third pump and a selector valve for the hydraulic circuit of a construction machine provided with a specific attachment. CONSTITUTION:Various hydraulic actuators of the hydraulic circuit of a construction machine are divided into two groups A and B. Hydraulic oil discharged from the first and second variable pump 1 and 2 is supplied to the groups A and B, and hydraulic discharged from the third pump 3 is supplied to a specific attachment device 10. A selector valve 19 is provided for the middle of an oil path 22 between the discharge side of a pilot pump 4 and the conventional valves 7 and 7' of regulators 5 and 6 for variable pumps 1 and 2. When operating the attachment device 10, the oil path 22 for the discharge side of the pilot pump 4 and the valves 7 and 7' is allowed to be connected with each other and switched by interlocking with the switching action of the switch valve 12.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a hydraulic circuit for a construction machine additionally equipped with an optional special attachment device.

Conventional Technology When a construction machine is additionally equipped with an optional special attachment device, there is a hydraulic circuit that uses a diverter valve device as a conventional technology. In other words, the 2
A diverter valve device is provided between each hydraulic pump and a switching valve for controlling various hydraulic actuators, and the diverter valve is switched by an external signal.

Then, take out the pressure oil from each of the two hydraulic pumps,
The pressure oil is supplied to a special attachment device for Ob/Gon. Figure 3 shows a conventional hydraulic circuit.
．． 32 are the 1st. In the second pump, 33 is a diversion valve device, 34 is a directional switching valve in the diversion valve device 33, 35 and 36 are each a diversion valve, and 37 is a switching valve for an optional special attachment (not shown).

Next, the operating function of the prior art hydraulic circuit shown in FIG. 3 will be described. The switching valves for various hydraulic actuators installed on construction machinery are arranged in parallel and divided into two groups A' and B''. Therefore, when the optional special attachment is not used, Leave the switching valve 34 in the A position.

Then, the pressure oil discharged from the first pump 31 is
8, position A of the directional switching valve 34, and is supplied to the switching valve of group A'' via the oil passage 39.40.Similarly, the second pump 3
The discharged pressure oil from No. 2 is supplied to the switching valves of group B' through the oil passage 38°, the A position of the directional switching valve 34, and the oil passages 39'' and 40''.

However, when operating the optional special attachment, the directional control valve 34 is switched from the A position to the Open position.

Then, the pressure oil discharged from the first pump 31 is
8. The mouth position of the directional control valve 34, the oil passage 41.42a, the C position of the diverter valve 35, and the oil passage 43 that reach the throttle part 44, but the throttle part 44 generates back pressure in the pilot oil passage 45. , the flow dividing valve 35 is switched from position C to position 2.

Similarly, the diverter valve 36 switches from the water position to the water position. Therefore, when the directional control valve 34 is switched from the A position to the mouth position, the flow dividing valve 35 changes from the C position to the 2 position, and the flow dividing valve 35 changes from the C position to the 2 position.
6 switches from the water position to the to position.

Therefore, the pressure oil discharged from the first pump 31 is transferred to the oil passage 38.
, the mouth position of the directional switching valve 34, reaches the oil passage 41, and a part of it reaches the oil passage 42b, the oil passage with the two-position throttle part of the diversion valve 35, and the oil passage 40.
The other pressure oil is supplied to the switching valve of group A'' through the oil passage 42a, the oil passage with the two-position throttle part of the diverter valve 35, the oil passage 43, the throttle part 44, and the oil passage 46. 47 will be refueled. Similarly, a portion of the pressure oil discharged from the second pump 32 is sent to the oil passage 47 via the oil passage 43'', the restriction part 44'', and the oil passage 46'' from the oil passage with the throttle part at the position of the diverter valve 36. The other part of the pressure oil is supplied to the switching valve of group B' through the oil path 40'.Therefore, the switching valve 37 for the optional special attachment has two positions, one for the diverter valve 35 and one for the diverter valve 36. The pressure oil diverted from the constricted portions 44, 44°,
The oil passes through oil passages 46 and 46', merges at oil passage 47, and is supplied.

Problems to be Solved by the Invention In the conventional hydraulic circuit using a diverting valve device as shown in Fig. 3 above, if the diverting accuracy of the diverting valve is not good, the oil supplied to groups A°, Bo, and optional special attachments. The amount is not accurately diverted, so e.g.
If the amount of oil supplied to the left travel motor in group A' and the right travel motor in group B° is not equal, straight forward travel is not possible. For this reason, the precision of the flow dividing valve device is high, and its structure is complicated and expensive. Furthermore, when construction machinery equipped with a diversion valve device is used, errors in the discharge flow rate of the plurality of hydraulic pumps are added to accuracy errors in the diversion valve itself, causing malfunctions in the operation of various hydraulic actuators.

Means for Solving the Problem The means of the present invention taken to solve the above problem are as follows: (a) 2.
Divide into groups A and B, 1st. Discharge pressure oil from the second variable pump is supplied to groups A and B, respectively, and the optional special attachment is arranged so as to supply discharge pressure oil from another third pump. Connect the pyro boats of both compen valves in the regulator for the second pump, and install a selector between the communication oil path from the pilot pump to the remote control valve for operating the special attachment device and the oil path between the pilot port and the pilot port. 2. On the other hand, connect the left pilot pressure receiving part and the right pilot pressure receiving part of the special attachment device switching valve via a shuttle valve, and e) Connect the shuttle valve to the pyloft pressure receiving part of the selector valve. The pilot pump discharge side oil passage can be connected to the pilot port of the compensator valve in the regulator, and when the optional special attachment device is operated, pressure oil is supplied from the third pump to the hydraulic actuator. , and the pilot pressure from the pilot pump is configured to be able to act on the compen valve for horsepower reduction control of the regulator via the selector valve.

Effect A. On construction machinery, if you operate either the switching valve in Groups A or B, and do not operate the optional special attachment, pilot pressure will not act on the selector valve, so the tank will not be connected without switching. This is the oil path location. Therefore, the first. Each compensator valve in the second variable pump regulator does not operate to reduce horsepower.

Operate either the switching valve in group A or B,
When the remote control valve of the optional special attachment is operated, the hydraulic actuator of the special attachment device is operated by the pressure oil discharged from the third pump. At the same time, the pilot pressure from the remote control valve acts on the pilot pressure receiving portion of the selector valve via the shuttle valve. For this purpose, the selector valve operates to switch the pilot pressure to the first. It acts on the compensator valve in the second variable pump regulator. So the first thing. The second variable pump is
The horsepower is reduced to reduce the input horsepower for the self-pump.

EXAMPLE Hereinafter, an example of the present invention will be explained in detail based on FIG. Various hydraulic actuators installed in construction machinery are controlled by switching operation of respective switching valves, and there are two types of operation methods: a remote control (hereinafter referred to as remote control) operation method and a direct push/pull operation method. FIG. 1 shows a remote control operation system, and in the figure, 1, 2, 3, and 4 are the first variable pump, second variable pump, and third pump, respectively.

The pilot pump, 5.6 is the regulator of the first variable pump 1 and the second variable pump 2, 7° and 7° are the compen valves of the regulators 5.6 and 8.8" are the compen valves of the compensator valve 7.7", respectively. Sole compensator piston, 9 and 9° are respectively pilot ports of compensator valve 7.7", 10
1 is a special attachment device for options, 11 is a hydraulic actuator equipped on the special attachment device 10, 12 is a switching valve for controlling the hydraulic actuator 11, 1
3.14 is the left and right pilot pressure receiving part of the switching valve 12, 15
16 is the remote control valve of the special attachment device 10, 16 is the operation lever for the remote control valve 15, and 17.18 is the remote control valve 15.
19 is a selector valve, 20 is a pilot pressure receiving part of selector valve 19, 21 is a shuttle valve, 22.23 is a pilot valve from pilot pump 4 to pilot valve 1
Oil passages leading to 7i8, 24a, 24b, 24c
25a and 25b are switching valves for various hydraulic actuators belonging to group A.

25c is a switching valve belonging to group B, 26.26' is a pump tilt angle adjustment valve in regulator 5.6, 27.27
' is a servo piston, 28 is a pump driving prime mover, 29
3 is a relief valve for the pilot pump 4, and 30 is an oil tank. Therefore, this hydraulic circuit divides various hydraulic actuators installed in construction machinery into two groups, A and B.
．． It is arranged so that the pressure oil discharged from the second variable pump 1.2 is supplied to groups A and B, respectively, and the pressure oil discharged from the third pump 3 is supplied to the optional special attachment device 10. . On the other hand, the first. The pilot ports 9 and 9 of compensating valves 7 and 7 for horsepower reduction control in the regulators 5 and 6 for the second pump 1.2 are connected, and the pilot ports 9 and 9 are connected to the pilot pump 4 discharge side oil passage 22 and the pilot bow) 9.9 A selector valve 19 was provided in the middle of the oil path. Further, the pilot pressure receiving parts 13 and 14 of the switching valve 12 for the special acnotation device 10 were connected via a shuttle valve 21, and the shuttle valve 21 was connected to the pilot pressure receiving part 20 of the selector valve 19.

The hydraulic circuit of the present invention is constructed as described above, and its operating functions will now be described. First, in the first case,
Without operating the optional special attachment device IO, the group A, B internal cutoff valves 24a, 24b,
A case where one or more of 24c, 25a, 25b, and 25c is operated will be described. Since the special acknowledgment device IO is not operated, the remote control valve 15 and scratching operation lever 16 are in the neutral position. Therefore, the pressure oil discharged from the pilot pump 4 is transferred to the oil path 22.
, the pilot pressure is only returned to the oil tank 30 via the relief valve 29, and no pilot pressure is drawn out from the pilot valves 17 and 18. Therefore, the selector valve 19 does not switch, so the pilot ports 9, 9' of the compensating valves 7, 7' for the regulators 5.6 communicate with the oil tank 30, and the 1st and 2nd pumps 1.2 control the horsepower. I don't receive it.

Second, a case will be described in which one or more switching valves in groups A and B are operated and the optional special acknowledgment device 10 is operated. When the operating lever 16 for the remote control valve 15 is switched from the neutral position to the t position or the t position, the pressure oil discharged from the pilot pump 4 passes through the oil passage 22, 23, and is connected to the pilot valve 17 or 18.
, acts on the pilot pressure receiving portion 13 or 14 of the switching valve 12 via the pilot oil passage 48 or 49. Therefore, the pressure oil discharged from the third pump 3 is sent to the hydraulic actuator 11 via the oil passage 50 and the switching valve 12, and the hydraulic actuator 11 is operated. On the other hand, the pilot pressure oil mentioned above is
shuttle valve 21 connected to pilot valve 17.18;
Pyro y)i[tl acts on the pilot pressure receiving section 20 of the selector valve 19 via the tl path 51. For this purpose, the selector valve 19 is operated to communicate the pilot pump 4 discharge oil passage 22 with the pilot port 9.9'' of the compensator valves 7 and 7'' in the regulators 5 and 6. acts on the compensating pistons 8, 8' through the oil passage 22, the selector valve 19, and the pilot ports 9, 9'.The movement of the compensating piston 8,8' causes the compensating valves 7,7' to operate, and the respective servo 1st and 2nd via piston 27.27゛
The pumps 1 and 2 are increased in horsepower so as to reduce the manual horsepower for self-pumping.

FIG. 2 is a hydraulic circuit diagram of another embodiment of the present invention, in which the switching valve operation method of various hydraulic actuators installed in the construction machine is a direct push/pull operation method (direct acting type). So, group A゛ in the hydraulic circuit.

Various switching valves belonging to "B" and switching valves for special attachment devices for options are also direct acting types.In Fig. 2, 1
0" is a special accessory device for the option, 12" is its direct-acting switching valve, 52 is the operation lever of the switching valve 12", 5
3 is an electric circuit, 54 is a limit switch in the electric circuit 53, 55 is a solenoid, 19 is a selector valve, 2
0' is the electromagnetic actuating part of the selector valve 19''. Therefore, in this hydraulic circuit, the selector is installed between the oil passages between the pilot pump 4 and the pilot ports 9 and 9'' of the compensating valves 7 and 7 in the regulator 5 and 6, respectively. A valve 19' is provided, while an electric circuit 53 is provided. The electric circuit 53
The inner limit switch 54 is a special attachment device l.
The electric circuit 53 is connected to the switching operation of the O° switching valve 12".
The switch valve 12 is connected to the lever 52 of the switching valve 12' so as to close the switch valve 12'. Further, the solenoid 55 in the electric circuit 53 is connected to the electromagnetic actuating portion 20'' of the selector valve 19'.

Here, the operating functions in the hydraulic circuit shown in FIG. 2 will be described. One or more switching valves in groups ^' and B' are operated, and the operating lever 52 of the switching valve 12'' for the special acnotification device 10'' is operated from the neutral position to either the push or pull position. Then, the pressure oil discharged from the third pump 3 passes through the oil passage 50 and the switching valve 12' to the hydraulic actuator 11.
Oil is sent to. At the same time, the limit switch 54 closes the electric path in conjunction with the operation lever 52, so that the electric circuit 53 is energized. Therefore, the solenoid 55 in the electric circuit 53
acts on the electromagnetic actuating section 20'' of the selector valve 19°.For this purpose, the selector valve 19' is turned off and the pilot pump 4 discharge side oil passage 22 is connected to the regulator 5.
, 6 internal compensator valve 7.7° pilot port 9.9°
be communicated with. Therefore, the pressure oil discharged from the pilot pump 4 is transferred to the compensator piston 8 of the compensator valve 7゜7゛.
, 8゛, so the 1st . The second pump 1.2 is deenergized to reduce the input horsepower for the self-pump. It should be noted that the respective pump tilt angle adjusting valves 26, 26' in the regulator 5, 6 have the same function as that of a typical variable pump.

Effects of the Invention As described above, in the hydraulic circuit for construction m1ti of the present invention, various hydraulic actuators are divided into two groups A and B. The arrangement was such that the discharge pressure oil from the second variable pump was supplied to groups A and B, respectively, and the discharge pressure oil from another third pump was supplied to the optional special attachment. Then, the pilot pump discharge side and the first. A selector valve is provided in the middle of the oil path between the compen valve of the regulator for the second variable pump, and when operating the special attachment device, the oil between the pilot pump discharge side and the compen valve for the regulator is connected to the switching operation of the selector valve. It is now possible to switch between routes.

In the prior art, a diverter valve device is provided between two hydraulic pumps and switching valves for various hydraulic actuators divided into two groups, and the diverter valves are switched by an external signal. Pressure oil is taken out from each of the two hydraulic pumps and is supplied to the optional special acknowledgment device.

However, in a conventional hydraulic circuit using a diversion valve device, unless the diversion accuracy of the diversion valve is good, the amount of oil supplied to the two groups of hydraulic actuators or special attachments cannot be accurately divided. Therefore, for example, unless the amount of oil supplied to the left travel motor in group A° and the right travel motor in group B is equal, straight travel is not possible.

For this reason, the precision of the flow dividing valve device is high, and its structure is complicated and expensive.

However, in the hydraulic circuit of the present invention, an inexpensive third pump and selector valve are provided instead of using the diverter valve device as in the prior art. Therefore, it is possible to reduce the cost of adding a special optional attachment device to a construction machine, and to solve the problem of poor flow accuracy. In addition, when one or more of the various hydraulic actuators and the optional special attachment are operated simultaneously, the input horsepower for each of the first and second variable pumps is increased to prevent overloading of the prime mover. , driving performance and economy can be improved.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic circuit diagram of the present invention, FIG. 2 is a hydraulic circuit diagram of another embodiment of the present invention, and FIG. 3 is a hydraulic circuit diagram of the prior art. 1...First variable pump 2...Second variable pump 3...Third pump 4...Pilot pump 5 .6...Regulator 7.7'...Compensation valve 9.9''...Pilot port 10...Special attachment device 12...
...Switching valve

Claims (1)

[Claims] Various hydraulic actuators equipped on construction machinery are divided into two groups A and B, and the actuators are arranged so that they are operated by two hydraulic pumps through respective switching valves, and special attachment devices for options are installed. In the additionally installed hydraulic circuit, a third pump is additionally installed, and a regulator 5 for the first and second variable pumps 1 and 2 is installed.
, 6, respectively, and a selector valve 19 is provided in the middle of the oil path between the pilot pump 4 and the pilot ports 9, 9', and a special attachment device 10 is installed. switching valve 12
By applying the switching operation signal to the selector valve 19, the pilot pump 4 discharge side oil passage 22 can be switched to communicate with the pilot ports 9, 9' for the compensator valves 7, 7', and the optional special attachment device 10 During operation, the hydraulic actuator 11 has a third
Pressure oil is supplied from the pump 3, and the pilot pressure from the pilot pump 4 is configured to be able to act on the compen valves 7, 7' for horsepower reduction control of the regulators 5, 6 via the selector valve 19. Features hydraulic circuits for construction machinery.