JPH02279840A - Hydraulic circuit for construction machinery - Google Patents

Abstract

PURPOSE:To improve safety and efficiency at execution of work by separating hydraulic actuators so that each can be operated by different two circuits supplied by two pumps, and by supplying pressure oil from the first pump to a motor for traveling and from the second pump to a motor for work-handling. CONSTITUTION:A hydraulic circuit of a hydraulic shovel is composed of passages comprising each of right and left valves 1R and 1L for traveling, each of right and left motors 8R and 8L for traveling and each of second and first pumps 26 and 25, and the passages are connected by each of bypass valves 47b and 47a. The circuit is further constructed in such that pressure oil from the first pump 25 and the second pump 26 can be supplied to a remote-control valve 9 for traveling and to a remote-control valve 17 for work-handling by operation of an independent valve 49 for traveling that is capable of being switched. When a switch 52 is operated, pressure oil from the pumps 25 and 26 are supplied independently to the remote-control valve 9 for traveling and to the remote-control valve 17 for work-handling. Thereby travel speed and work-handling speed will not vary even under simultaneous operation of traveling and work-handling.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates primarily to hydraulic circuits for construction machines such as hydraulic excavators.

Conventional technology Figure 2 is a circuit diagram of the main parts of a conventional hydraulic excavator.
In the figure, LL, IR, 2A, 2a.

3.4.5, 6.7 are switching valves for operating various hydraulic actuators installed in hydraulic excavators, of which 1+, , I
R is the left and right travel valves, 8t, 8FL are the left and right travel motors, 9 is the travel remote control valve that operates the travel valves IL and IR, 1
0.11, 12.13 are pilot valves in the travel remote control valve 9, 14°, 15.16 are shuttle valves for deriving pilot pressure, and 17 are other actuators (not shown) installed in work attachments for hydraulic shovels, etc. ), 18, 19, 20, and 21 are pilot valves in the remote control valve 17 for other actuators, respectively.
22, 23, and 24 are shuttle valves for pilot pressure derivation, 25.26 are the first and second pumps, and 27
．． 28 is the first. Regulators for the second pumps 25 and 26, 29 is a pilot pump, 30A and 30a are low pressure relief valves for setting negative control pressure, 31^, 31
B is a throttle portion, 32A and 32B are center bypass oil passages, 33 is an oil tank, 34 is a straight travel valve, 3
5 is a pilot selection conduction valve. Note that the symbols ■-■, @-◎, 0-0. @-■ indicates the connection relationship of the pilot oil passages. Further, the pilot oil passage from the remote control valve 17 for other actuators is connected to the other actuator operation switching valves 2A, 2B, 3. . . , 7 is a typical example.

Next, the configuration of a conventional hydraulic circuit will be described with reference to FIG. 2 types of hydraulic actuators installed on hydraulic excavators
Divide into groups A and B, respectively. Second pump 25
．． I am trying to drive it with 26. Also, left and right travel valve IL
, IR to group A.

B, and these and other actuator operation switching valves are connected in tandem, and the other actuator operation switching valves are connected in parallel. In addition, a traveling straight valve 34 is provided on the discharge side of the first and second pumps 25 and 26.
When the travel motor 81.8R and other actuators are operated simultaneously, the pressure oil from the first pump 25 is transferred to the left and right travel motors 8L, 8R by the switching operation of the straight travel valve 34.
The configuration is such that it is supplied in parallel to the

Next, the functions of the conventional hydraulic circuit will be described. First, as a first case, a case will be described in which one of the other actuators is operated while the left and right travel motors 81 and 83 are stopped. Since the traveling remote control valve 9 is not operated, no pilot pressure is derived from the shuttle valve 16. Therefore, at the same time that the pilot selection conduction valve 35 is in the cutoff oil passage position H, the straight travel valve 34 is also in the cutoff oil passage position H. Therefore, the other actuators belonging to group A are supplied with pressure oil from the first pump 25, and the other actuators belonging to group B are supplied with pressure oil from the second pump 26, respectively.

Next, as a second case, a case where only the left and right travel valves IL and IR are operated simultaneously will be described. Since the traveling remote control valve 9 is operated, pilot pressure is derived from the shuttle valve 16, and the pilot selection conduction valve 35 is switched from the cutoff oil passage position E to the open oil passage position. However, since the remote control valve 17 for other actuators is not operated, the shuttle valve 2
No pilot pressure is derived from 4. Direct travel valve 34
is the state at the cutoff oil path position A. Therefore, the first and second
Pressure oil from pumps 25 and 26 is supplied to left and right travel motors 8L and 8R, respectively.

Next, a third case will be described in which the left and right traveling valves IL and IR are simultaneously operated and one of the other actuators is operated. Since both the travel remote control valve 9 and the other actuator remote control valve 17 are operated, the pilot selection conduction valve 35 is switched to the open oil passage position, and the pilot pressure derived from the shuttle valve 24 is applied to the straight travel valve 34. act. The straight travel valve 34 is operated to switch from the cut-off oil passage position H to the open oil passage position G. Therefore, the pressure oil from the first pump 25 is transferred to the oil passage 36, 37 and the check valve 3.
8. Branches from the outlet of the check valve 38, one of which is connected to the oil line 3
9. It is supplied to the left travel motor 8L via the left travel valve IL. At the same time, the other oil is supplied to the right travel motor 8R via the oil passage 40, the opening oil passage position of the straight travel valve 34, the oil passages 41 and 42, and the right travel valve IR. This allows the hydraulic excavator to travel straight ahead without meandering.

However, the vehicle speed of the hydraulic excavator in the third case above is
This is halved compared to the first case.

The hydraulic circuit in Fig. 2 is of the negative control type, so it is group A.

The most downstream side negative control pressure of the center bypass oil passages 32A and 32s in B is set to 1. It is made to act on the regulators 27 and 28 of the second pump 25 and 26. So, when the hydraulic excavator is working, the first thing. Second
When the discharge pressure of each of the pumps 25, 26 increases, that is, the negative control pressure decreases, the pump tilt angle is automatically adjusted, the pump discharge flow rate decreases, and the absorbed horsepower is limited.

Problems to be Solved by this Invention In hydraulic excavators equipped with conventional hydraulic circuits, other actuators (for example, work attachments, etc.)
When operated, the traveling speed is reduced by switching the straight travel valve. Then, when the operation of the other actuators is stopped, the traveling speed suddenly increases again. As a result, the load may swing in a pendulum state when the suspended load is traveling, or may fall out of the packet while the ready-mixed concrete is being transported. Further, if a work attachment or the like is operated while the vehicle is traveling at a slow speed by adjusting the traveling control lever, the pump discharge flow rate increases and suddenly becomes faster for the same reason as above. However, when the operation of the work attachment is stopped, the traveling speed suddenly decreases. Also, if you drive while making fine adjustments to the work attachment,
The operating speed of the work attachment becomes faster, and furthermore, when the traveling is stopped, the operating speed of the work attachment becomes slower.

As mentioned above, when traveling and operating other actuators at the same time or repeatedly, the traveling speed and the operating speed of other actuators change each time, which is dangerous for driving and may cause trouble during construction work. was.

The purpose of this invention is to solve the above-mentioned problems and provide a hydraulic circuit for construction machinery that is improved so that when traveling and other actuators are operated simultaneously or independently, the traveling speed and the operating speed of other actuators do not fluctuate each time. shall be.

Means for solving the problem A. The left running valve is installed in the front row of group A, and the right running valve is installed in the last row of group B. A bypass valve is provided in each of the spring bus oil passage for the actuator that communicates with the downstream outlet, and the bypass oil passage for the right travel valve that communicates with the center bypass inlet and outlet of the right travel valve. The pressure oil introduction oil passages of each group into which pressure oil is introduced during the switching operation of the switching valve are communicated via a parallel communication valve, and the parallel communication valve is normally set at a cutoff oil passage position; 2. Further, A travel independent command valve is provided which is switched by operating a switch, and pilot pressure from the travel remote control valve and other actuator remote control valves is applied to the bypass valve and parallel communication valve by the switching operation of the travel independent command valve. When the above switch is operated, the travel remote control valve and the remote control valve for other actuators are operated individually or both are operated simultaneously, the pressure oil from the first pump is used for the left and right travel motors, and the pressure oil from the second pump is used for the other actuators. It was configured to supply

Operation a. When the switch is in the OFF state, the travel independent command valve is in the tank communication oil path position. Therefore, the pilot pressure does not act on the bypass valve (and the parallel communication valve). The functioning in this case is therefore similar to that of prior art hydraulic circuits.

When the switch is turned on, if either the travel remote control valve or the remote control valve for other actuators is operated at the same time, the bypass valve, parallel communication valve, and straight travel valve will all open oil passages from the cut-off oil passage position. Switch to position. Therefore, in this state, when the travel remote control valve and the remote control valves for other actuators are operated individually or simultaneously, pressure oil from the first pump is supplied to the left and right travel motors, and pressure oil from the second pump is supplied to the other actuators.

C. First, as described above. Since pressure oil is supplied from each of the second pumps, even if you stop traveling while operating the work attachment while traveling, and even if you stop or restart the operation of the work attachment, the traveling speed will not change.
The operating speed of other actuators does not change each time.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings. FIG. 1 is a circuit diagram showing a hydraulic circuit according to the present invention. In the figure, the same reference numerals are given to the same components as in the prior art. 43-44 are bypass oil passages for other actuators arranged in group A, 45-
46 is a bypass oil passage for the right traveling valve arranged in group B;
47A47B are bypass valves, 48 is a parallel communication valve, 49 is an independent travel command valve, 50 is a solenoid for the independent travel command valve 49, 51 is an electric circuit, 52 is a switch,
53 is a power source, 35' is a pilot selection conduction valve, and 54 is a shuttle valve. In addition, as switching valves for operating other actuators, 2A is the boom I valve, 2B is the boom ■ valve (boom E valve 2^ and boom ■ valve 2B perform simultaneous switching operation for merging), 7 is the arm I valve, and 3 is the boom ■ valve. Arm ■ Valve (Arm ■ Valve 3
and Arm E valve 7 perform simultaneous switching operation for merging), 4 is a packet E valve, 5 is a packet ■ valve (packet ■ valve 5 and packet I valve 4 perform simultaneous switching operation for merging), and 6 is a swivel valve. .

Next, the configuration of the hydraulic circuit according to the present invention will be described with reference to FIG. The left travel valve IL is provided in the front row of group A, and the right travel valve IR is provided in the last row of group B, and the ratio between the center bypass outlet of the left travel valve It and the center bypass (32A) of group A is the most downstream side. Bypass oil passages 43-44 for other actuators that communicate with Ronu, and the right travel valve IR
A bypass valve 47 is installed in each of the bypass oil passages 45-46 for the right traveling valve that communicates the center bypass port port and the outlet hole.
A and 47B were installed. In addition, each switching valve (2A.

Groups A and B that introduce pressure oil during the switching operation of ~, 7)
Each of the pressure oil introduction oil passages and the pressure are communicated through the parallel communication valve 48, and the parallel communication valve 4 is normally connected to the parallel communication valve 48.
8 was set to the shutoff oil path position. In addition, switch (5
2) A travel independent command valve 49 is provided which is switched by operation, and the switching operation of the travel independent command valve 49 transfers pressure from the travel remote control valve 9° and other actuator remote control valves 17 to the bypass valve 47A, 47a and the parallel communication valve 48. When operating the parallel communication valve 48.52, the travel remote control valve 9. When the remote control valves 17 for other actuators are operated individually or when both of the above 9.17 are not operated at the same time, the pressure oil from the first pump 25 is transferred to the left and right travel motors 8L and 8R.
The configuration is such that pressure oil from the pump 26 is supplied to other actuators.

Note that the left-right relationship between the left and right travel valves IL and IR in groups A and B in the above hydraulic circuit is not set for clarity of explanation. Also, a bypass valve 47A.

47B is designed to be switched by the pilot pressure derived through the independent travel command valve 49, but the independent travel command valve 49 is replaced with an electromagnetic bypass valve that is simultaneously switched and activated by switch operation. Good too.

Next, the functions of the hydraulic circuit according to the present invention will be described. When the switch 52 is turned off, the independent travel command valve 49 is de-energized and is located in the tank communication oil path 1, so that the pilot pressure does not act on the bypass valves 47A and 478. . Since the bypass valves 47A and 473 are both in the shutoff oil path position, their function in this case is similar to that of the prior art hydraulic circuit. Next, switch 52 is turned on. Since the solenoid 50 is energized, the travel independent command valve 49 is switched from the tank communication oil path position to the open oil path position. In this state, in the first case, the left and right travel motors 8L, 8
A case will be described in which one of the other actuators is operated while R is stopped. pilot bong 29
The pilot pressure discharged from the oil line 55.57.58
, at the opening oil passage position of the travel independent command valve 49, the oil passage 59 branches there, and one side passes through oil passages 60, 61 and 62, and acts on the bypass valves 47A and 47B. Both bypass valves 47A and 47B are switched from the cutoff oil passage position to the open oil passage position. Further, the pressure of the other pipe convex branched at the oil passage 59 is transferred to the oil passage 63, the shuttle valve 54, and the oil passage 64.
, where it branches, and one side passes through an oil path 65 and acts on the straight travel valve 34 . The other side acts on the parallel communication valve 48 via the oil passage 66. Straight travel valve 34. The parallel communication valves 48 are at the open oil path positions at the same time.

Switch to evening. Therefore, the pressure oil from the first pump 25 is transferred to the oil path 36, 37, 67, the neutral position of the left traveling valve IL, and the oil path 6.
8. Bypass oil passage 43, opening oil passage position of bypass valve 47A, bypass oil passage 44, oil passage 69, low pressure relief valve 30
A and the constriction section 31A, and then returned to the oil tank 33. However, the pressure oil from the second pump 26 flows through the oil path 70.7.
1. Branched there, and one side has an oil passage 72 and a check valve 73.
, oil passage 74.75, opening oil passage position of parallel communication valve,
The oil passage 76 is connected to the other actuator operation switching valve of group A, and the oil passage 71 branches off to the other oil passage 77.
It is then supplied to the other actuator recurrent switching valves of group B.

Next, in the second case, turn on the switch 52,
A case will be described in which only the left and right traveling valves IL and IR are operated. In this case as well, as in the first case, the pilot pressure from the two pilot pumps acts on the bypass valves 47A, 47B, the straight travel valve 54, and the parallel communication valve 48 through the open oil passage position of the travel independent command valve 49. , the bypass valves 47A, 47B, and the straight travel valve 54. Parallel communication valve 4
8 to the open oil passage position at the same time. Therefore, the pressure oil from the first pump 25 is transferred to the oil passages 36, 37, the check valve 38,
Branching from the outlet of the check valve 38, one is an oil passage 39;
It is supplied to the left travel motor 8L via the left travel valve IL.

At the same time, the other oil is supplied to the right travel motor 8R via the oil passage 40, the open oil passage position of the straight travel valve 34, the oil passage 41, 42, and the right travel valve IR.

Next, as a third case, turn on the switch 52,
Remote control valve for traveling 9 and remote control valve for actuator 1
The case where 7 is operated simultaneously will be described. In this case as well, the above 1. As in the second case, pilot pressure acts,
Bypass valves 47A, 47B + straight travel valve 54. The parallel communication valve 48 is simultaneously switched to the open oil passage position. (In this case, the pilot selection conduction valve 35' also performs the switching operation,
This pilot selection conduction valve 35' functions when the excavator performs work with the switch 52 in the OFF state. ) Therefore, the pressure oil from the first pump 25 is supplied to the left and right travel motors 8L and 8R, and the pressure oil from the second pump 26 is supplied to other actuators.

When the switch 52 is turned on as described above, in any case, the first . The pressure oil from the second pumps 25° and 26 is supplied to the left and right travel motors 8I and 8R independently, respectively.
Supplied to other actuators. As a result, when operating the work attachment while the hydraulic excavator is running,
Even if the vehicle stops traveling or the operation of the work attachment is stopped or restarted, the traveling speed and other actuator operating speeds do not change each time.

In addition, in the embodiment of this invention, a negative control type hydraulic circuit (
1), the same application can be made to a positive control type hydraulic circuit.

Effects of the Invention In a hydraulic excavator equipped with a conventional hydraulic circuit, when another actuator (for example, a work attachment, etc.) is operated while the excavator is running, the traveling speed is reduced by the switching operation of the straight-travel valve. Then, when the operation of the other actuators is stopped, the traveling speed suddenly increases again. As a result, when the suspended load was traveling, the load swayed in a pendulum state, and the ready-mixed concrete sometimes fell out of the packet during transportation. In other words, when traveling and operating other actuators simultaneously or independently, the traveling speed and operating speed of other actuators change each time, making the operation dangerous and causing trouble during construction. was.

However, in the hydraulic circuit according to the present invention, a travel independent command valve is provided which is switched by a switch operation, and the pilot pressure from the travel remote control valve and the remote control valve for other actuators is communicated with the bypass valve and in parallel by the switching operation of the travel independent command valve. I made it work on the valve. As a result, when the above-mentioned switch is operated, when the travel remote control valve and the remote control valve for other actuators are operated individually or both are operated simultaneously, the pressure oil from the first pump is supplied to the left and right travel motors, and the pressure oil from the second pump is supplied to the left and right travel motors. is supplied to other actuators.

Therefore, in the construction machine equipped with the hydraulic circuit according to the present invention, when operating the work attachment while running, even if the running is stopped or the operation of the work attachment is stopped or restarted, the running speed and other Since the actuator operating speed does not change each time, safety and work reliability are improved.

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram according to the present invention, and FIG. 2 is a hydraulic circuit diagram of the prior art. IL, 1st generation Left and right travel valves 8L, 8R left and right travel motors 9 Remote control valve for travel 17 Remote control valve for other actuators 25 1st pump 26 2nd pump 29 Pilot pump 34 Straight travel valve 35.35' Pilot selection conduction Valve 47^, 4
7e-Bypass valve 48 Parallel communication valve 49 Travel independent command valve 52 Switch and above Patent application Toshiaki Sawara Representative of Jinyutani Heavy Industries Co., Ltd.

Claims (1)

[Claims] (1) Various hydraulic actuators installed on construction machinery 2
The left and right traveling valves are respectively arranged in each group, and these and other actuator operation switching valves are connected in tandem, and are driven by first and second pumps, respectively. Other actuator operation switching valves are connected in parallel, and a direct travel valve is provided that communicates the oil pressure supply sources of the left and right travel valves, and when the travel motor and other actuators are operated simultaneously, the straight travel valve is switched. In a hydraulic circuit configured to supply pressure oil from the first pump to the left and right travel motors in parallel, one travel valve is provided in the front row of group A, and the other travel valve is provided in the last row of group B. , a bypass oil passage for another actuator that communicates between the center bypass outlet of one of the traveling valves and the most downstream outlet of the center bypass of group A, and a bypass for the other traveling valve that communicates with the center bypass inlet and outlet of the other traveling valve. A bypass valve is provided in each of the oil passages, and an independent travel command valve that is switched by switch operation is provided, and by switching the independent travel command valve, pilot pressure from the travel remote control valve and remote control valve for other actuators is transferred to the bypass valve. and the parallel communication valve, so that when the above switch is operated, the travel remote control valve and the remote control valve for other actuators are operated individually or both are operated simultaneously, the pressure oil from the first pump is applied to the left and right travel motors. A hydraulic circuit for construction machinery, characterized in that the hydraulic circuit is configured to supply pressure oil from a second pump to another actuator.