JPS60203743A - Hydraulic circuit for construction machinery such as hydraulic shovel - Google Patents

Abstract

PURPOSE:To enable to perform straight forward running even if other actuator is actuated during running of a machinery, by a method wherein, in a hydraulic circuit formed with two direction switching valve groups and 2 hydraulic pumps, a switching valve is disposed between the hydraulic pumps. CONSTITUTION:In the case of only running of the vehicle, a switching valve 6 is brought to a position A, and pressure oil is individually fed to direction switching valves 4d and 5c for running on both sides with the aid of hydraulic pumps 1 and 2. When an arm is actuated during running, the switching valve 6 is brought to a position B to operate it. In which case, pressure oil in the hydraulic pump 1 is distributed to lines 7 and 8, pressure oil in the hydraulic pump 2 is distributed to lines 9 and 10, and pressure oil from the 2 pumps is joined together to feed it to the direction switching valves 4d and 5c for running on both sides. With an arm being controlled, pressure oil, flowing through the line 7 of the pump 1, is fed to an arm direction switching valve 4b, but the lines 9 and 10 are in a communication state, and this causes uniformization of an amount of oil to running motors on both sides.

Description

[Detailed description of the invention]

(Technical field of the invention) The present invention is directed to Ura 1. r: Regarding hydraulic circuits such as excavators, in particular, hydraulic circuits that are equipped with multiple actuators and that allow each actuator to operate normally while traveling straight even if other actuators other than those for driving are activated while the vehicle is traveling. It is related to. (Technical Background of the Invention) In a conventional oil IIE pump, the directional valve group is connected in parallel to the LL. For this reason, the amount of oil supplied to the travel motor side of the directional control valve group that operates the actuator, such as the arm with a light load, is greater than the amount of oil supplied to the travel motor side of the directional control valve group operated by another force. It becomes less and meandering. Further, there is a problem in that the actuator does not operate when another actuator with a high load pressure is operated. The above problem will be explained in more detail below with reference to FIG. FIG. 1 is a circuit diagram of a conventional hydraulic excavator. 1 is a first hydraulic pump, 2 is a second hydraulic pump, 3 is a first hydraulic pump.
It is the prime mover that drives the second hydraulic pump 1.2. 4 is a group of first directional valves, including a turning directional valve 4 a
Directional switching valve for % arm 4b1 Directional switching valve for second boom 4
cs consists of one direction switching valve 4d for left and right travel (hereinafter explained as F-person regular travel). These directional valves are connected in parallel. Therefore, there is no functional problem even if the order of the directional control valves is changed. 5 is a second directional valve group;
First boom directional switching valve 5a, packet directional switching valve 5
b, the other direction switching valve 5c for left and right travel (hereinafter described as right travel), and similarly connected in parallel. Therefore, like the first directional valve group 7, there is no functional problem even if the order of the directional valves is changed. The conventional hydraulic circuit configured as described above has the following problems. ■) While traveling straight, that is, simultaneously operating the left direction 9 direction switching valve 4d and the right direction direction switching valve 5C in the same direction,
When attempting to operate the arm, use the arm directional control valve 4.
b and the left travel direction switching valve 4d are connected in parallel, so the pressure oil flows to the arm direction switching valve 4b side, which has a lighter load compared to the IJJ direction switching valve 4d side for people traveling, and the direction switching valve 4d for left travel is connected in parallel. Fixed? 11: The amount of oil flowing into the directional control valve decreases, and the speed of the left travel motor becomes slower than the speed of the right travel motor, making direct travel impossible. Y! The traveling drive box moves the arm 1. If it is lower than IE, there will be insufficient pressure in the arm cylinder and the arm will not be able to operate. 1

[) When performing a turning operation while traveling straight, the turning direction switching valve 4a and the left running direction switching valve 4d are connected in parallel, so the turning direction is different from the left running direction switching valve 4d side. The LEE oil flows toward the switching valve 4a side, and the pressure oil flowing to the left travel direction switching valve decreases by that amount, and the speed of the left travel motor becomes slower than the right travel motor speed, making it impossible to travel straight. If the running drive pressure is lower than the swing drive pressure, there will be insufficient pressure for the swing motor, making it impossible to swing. l) When operating the packet while traveling straight, the packet directional switching valve 5b and the right-hand directional switching valve 5c are connected in parallel, so the load is lighter compared to the right-hand directional switching valve 5c. The pressure oil flows to the packet directional switching valve 5b side, and the pressure oil flowing to the right running directional switching valve decreases by that amount, and the speed of the right running motor becomes slower than the speed of the left running motor, and straight running becomes impossible. Furthermore, if the traveling driving pressure is lower than the packet moving pressure, there is insufficient pressure in the bow cylinder, and the packet operation cannot be performed. ■) When operating the boom while traveling straight, the first boom directional switching valve 5a and the right running directional switching valve 5c
Since the boom directional control valve 4C and the left running directional control valve 4d are connected in parallel, the pressure oil flowing to the left and right running directional control valves is equal, but the driving state is higher than the boom moving pressure. If it is low, the first. Since sufficient pressure oil cannot be supplied to the second boom directional control valves 4c and 5a to raise the boom, a situation occurs in which the boom cylinder cannot be extended. (Objective of the Invention) The present invention has been made to solve the above-mentioned various problems.Even if other actuators are operated during running, straight running can be maintained, and even if other actuators are operated, This invention aims to provide a hydraulic circuit that allows the actuator to operate sufficiently. (Summary of the Invention)
This was done to determine W, and the actuator's 11Z
'Of the plurality of directional valve groups that control the direction of oil θ11, one directional valve group has a turning nozzle jlI'
At least one of the 117J switching valves, the boom directional switching valve, the second boom directional switching valve, and one of the 9 traveling direction switching valves are connected in parallel in sequence. Therefore, it is a mistake. These directional reno diversion valves order! There is no functional problem even if they are replaced. Then, it is connected in tandem via a throttle and a load check valve to a parallel passage connected to one of the left and right travel direction switching valves (hereinafter described as a passenger travel direction switching valve). In the other group of directional control valves, at least one of the first boom directional control valve, the packet directional control valve, etc. and the other travel directional control valve are connected in parallel. Therefore, there is no functional problem even if the order of these switching valves is changed. Then, it is connected in tandem via a throttle and a load check valve to a parallel passage connected to the other of the left and right running direction switching valves (hereinafter described as F right running direction switching valve). And the first of these. The second directional valve group includes the directional valve group and the first directional valve group. The pressure oil from each oil 11 mobomb is connected to the second flow of each directional valve group through the switching valve installed between the second hydraulic pump and the left-hand running through the throttle and load check valve. When the switching valves are switched, the pressure oil from one oil IJE pump is supplied between the first and second directional switching valves and the load check valve. Second
The 1st royal oil of the E pump is supplied to the upstream of the directional control valve group, and the 1st royal oil of the E pump is supplied to the 1st. The second direction J switching valve group is designed so that it can be supplied between the left and right traveling direction switching valves and the load check valve, respectively. (Embodiments of the Invention) Hereinafter, embodiments of a hydraulic circuit for a construction machine such as a hydraulic excavator according to the present invention will be described. FIG. 2 is a hydraulic circuit diagram of a first embodiment of the present invention, and FIG. 3 is a hydraulic circuit diagram of a second embodiment of the present invention. Note that in these figures, the same components as those shown in FIG. Now, in FIG. 2, 6 is the switching valve 1. The second hydraulic pump +, zt/h and the first. The connection between the hydraulic pump 1.2 and the switching valve groups 4, 5 is switched by the single-serving switching valve 6, which is disposed between the second direction 9J switching valve groups 4, 5. The switching method of this switching valve may be manual operation by the operator's hands, operation using a pedal with the foot, or electric type or hydraulic type. 4f is a throttle provided in the parallel passage of the left-hand travel direction switching valve 4d with the load check valve 4e, and 5e is a load check valve 5 in the parallel passage for the right-hand travel direction change-over valve 5c.
This is a diaphragm installed in series with d. 12.13 is a relief valve that regulates the maximum pressure of the hydraulic pumps 1 and 2. With this configuration, a) when the switching valve is in the A position (the state shown in the figure), the pressure oil of the first hydraulic pump 1 is passed through the pipe 7 to the turning valve of the group 4 of the first directional switching valve; Directional switching valve 4
a It is supplied in parallel to the directional switching valve 4b for the S arm, the second directional switching valve 4c for the boom, and the directional switching valve 4d for left running, and also passes through the conduit 9 through the throttle 4f7 and the load check valve 4e. It is supplied between the load check valve 4e& and the 1J river direction switching valve 4d, which are connected in parallel. On the other hand, the pressure oil of the second hydraulic pump 2 passes through the conduit 8 to the first boom directional valve 5aJ and the boom directional valve 5b of the second directional valve group 5.
and the right-hand direction change-over valve 5C, and are connected in parallel through the conduit 0 to the right-hand direction change-over valve 5C and the right-hand direction change-over valve 5C. 5C and the load check valve 5d. ) Also, when the reno switching valve is switched to position B, the pressure oil of the first hydraulic pump 1 passes through the pipe 7 to the swing directional switching valve 4as arm direction of the group 4 of the first directional switching valve. It is supplied to the switching valve 4b, the second boom directional switching valve 4cs, and the left running directional switching valve 4d, and also passes through the conduit 8 to the first boom directional switching valve of group 5 of the second directional switching valve. The valves 5 a, , , are supplied in parallel to the directional switching valve 5b for kenote and the directional switching valve 5c for right travel, and the oil for the second hydraulic pump 2 passes through the pipe 9 to the first directional switching valve. A directional control valve 4d for left travel is connected in parallel to group 4 of the throttle 4f7J and a load check valve 4e.
and the load check valve 4e, and through the conduit 10 to the second group 5 of directional valves 5.
The fuel is supplied between the valve 5c and the load check valve 5d, which are connected in parallel to each other via the load check valve 5d. (Function) The function of the hydraulic circuit configured as described above will be explained. A) When only the left running direction switching valve 4d and the right running direction switching valve 5c are operated at the same time with the switching valve 6 in the A position as shown in FIG.
The pressure oil from the hydraulic pump 1 is distributed to the line 7 and line 9 via the switching valve 6, and the pressure oil that has passed through the fort/line 7 is distributed from the center bypass passage of group 4 of the first directional valve. It passes through the throttle 4f and the load check valve 4e and is supplied to the left travel direction switching valve 4d which is connected in parallel. Further, the pressure oil that has passed through the pipe line 9 is supplied between the left travel direction changeover valve 4d and the load check valve 4e, and the left travel direction changeover valve 4
d. That is, the entire amount of pressure oil from the first hydraulic pump 1 is supplied to the left travel direction switching valve 4d. Further, the pressure oil of the second hydraulic pump 2 is distributed to the pipe line 8 and the pipe line 10 via the switching valve 6, and the pressure oil that has passed through the pipe line 8 is distributed to the second pipe line 8 and the pipe line 10 via the switching valve 6.
It is supplied from the center bypass passage of group 5 of the directional control valves through the throttles 5e/& and the load check valves 5d to the right-hand directional control valve 5c connected in parallel. Further, the pressure oil that has passed through the pipe 10 is supplied between the right travel direction changeover valve 5c and the load check valve 5d, and is then supplied to the right travel direction changeover valve 5c. That is, the second hydraulic pump 2
The entire amount of pressure oil is also supplied to the right travel direction switching valve 5c. B) When operating the left running directional switching valve 4d and the right running directional switching valve 5c in the same direction to perform other operations, such as arm operation, while the vehicle is running straight, the arm JJ direction 9J switching valve 4b
When switching to the right or left, oil from the first hydraulic pump 1 is supplied to the arm as explained in the conventional A11l-:circuit, and that amount is not supplied to the left travel motor.
EMI+ decreases and the speed of the left travel motor decreases, causing it to meander. Therefore, before operating the arm directional switching valve 41), the switching valve 6 is switched from the illustrated position to the B position. First, with the uJ switching valve 6 switched to position B+i, each oil 1]:, the pump I
To explain the flow of the first oil 1-E pump 1, the pressure oil from the first oil 1-E pump 1 is distributed to the pipe 7 and the oil passage 8 via the switching valve 6, and the pressure oil that has passed through the pipe 7 is distributed to the first oil 1-E pump 1. Group 4 of directional valves
from the parallel passage to the throttle 4f and load check valve 4e.
The pressure oil that has passed through the pipe line 8 is supplied from the parallel passage of the second directional valve group 5 through the throttle 5e and the load check valve 5d. It is supplied to the parallel-connected right travel direction switching valve 5c. Further, the pressure oil from the second hydraulic pump 2 is distributed to the pipe line 9 and the pipe line 10 via the switching valve 6, and the pressure oil that has passed through the pipe line 9 is distributed to the load check valve 4e and the left travel direction switching valve 4d. Pressure oil is supplied from between the load check valve 5d and the right-hand direction change-over valve 4d to the left-hand direction change-over valve 4d, and the pressure oil that has passed through the pipe 10 is supplied to the right-hand direction change-over valve 5C from between the load check valve 5d and the right-hand direction change-over valve 5c. supplied to In other words, the IE oil of the first hydraulic pump 1 and the oil 1-F of the second hydraulic pump 2 are merged into the left travel direction switching valve 4d and the right travel direction change valve 5C.
will be supplied in parallel. At this time, pump I
. It seems that the amount of oil from 2 is not divided equally between the left and right running motors, but depending on the nature of the crawler itself, the entire track 11k is divided equally and if it maintains a constant running. When the arm directional J switching valve 4b is operated from this position,
The pressure oil from the hydraulic pump 1 was distributed to the pipe line 7 and the pipe line 8 via the switching valve 6, and passed through the pipe line 7.
direction [2J is supplied to the arm directional switching valve 4b in group 4 of switching valves. In addition, the IE oil that has passed through pipe 8 is passed through the parallel passage of group 5 of the second directional control valve to throttle 5 e.
It is supplied to the j-plane switching valve 5c (for right travel) via the XM and load check valve 5d. Moreover, the pressure oil from the oil IJ ball pump 2 is distributed to the pipe line 9 and the pipe line 0 via the switching valve 6,
The pressure oil that has passed through the pipe line 9 is transferred from between the load check valve 4e and the left travel direction changeover valve 4 [1] to the left travel direction changeover valve 4d.
is supplied to the traveling direction switching valve 5c. At this time, among the pressure oil from the above-mentioned hydraulic pump l, pipe line 8
The pressure oil that has passed through pipe 9. ] 0 communicate with each other via the switching valve 6, it is also distributed to the left travel direction switching valve 4d, and the amount of oil is distributed to the left and right travel motors due to the inherent straightness of the crawler itself, which is a traveling body. is evenly distributed to keep the vehicle running straight. At this time, if the drive pressure of the arm is low, the pressure oil from the hydraulic pump 1 will not be supplied to all the IR arms, and the pressure oil from the hydraulic pump 2 will be evenly distributed to the left l side 7 demotor, so while moving the arm, the pressure oil will not be supplied to all the IR arms. Facultability can be maintained. If the arm drive pressure E is higher than the traveling drive pressure,
The drive pressure for the arm is secured by the throttle 5e, and the excess oil that does not move the arm is equally distributed to the left and right travel motors, as described above, so it is possible to maintain straight travel while moving the arm. C) Next, while traveling straight ha; When performing rotation operation, boom movement, bucket operation, etc., it is possible to operate other actuators without maintaining straightness by switching and operating the pot valve 6. However, since it is basically the same as the above explanation, it will be omitted. FIG. 3 shows a second embodiment, which has basically the same configuration as the embodiment shown in FIG. In the second embodiment, the operation method was manual, but in the second embodiment, the switching was made automatic for the pilot. The structure of the differences will be described below. 1 is a leaf valve that regulates the maximum pressure of the pilot pump 11; 15 is a travel auxiliary switching valve that is linked with the right directional switching valve 5c; I6 is a traction auxiliary switching valve that is linked with the left directional switching valve 4d; Reference numeral 17 denotes a conduit connecting the pilot pump I2 and the traveling assist switching valve 15, and 18 and 19 denotes a conduit connecting the traveling/auxiliary switching valves 15 and 16. 2o
22 is an auxiliary switching valve that connects the running yarn auxiliary 9 switching valve 16 and the auxiliary 17J switching valve 21 that operates in conjunction with the directional switching valve when at least one actuator that has a unique characteristic for running is activated. This is a pipe line that connects the valves 21 and 11 [J with the operating section of the switching valve 6. Next, I will explain the BJ work. A) When traveling only straight ahead, switch the left travel directional control valve 4d to state A (or B) and the right travel directional control valve 5c to state A (or B), and the pilot pump The pressure oil from 11 is led to pipe 19 (or pipe +8) via travel assistance switching valve 15, and reaches auxiliary switching valve 21 through travel assistance switching valve 16, pipe 20, and so on. However, at this time, since the other actuators are not operating, the auxiliary switching valve 21 is maintained in the state A (blocked) and the pipe line 2
Since pressure oil is not guided to 2, the switching valve 6 continues to maintain the state of . Therefore, the operation is the same as that of the conventional hydraulic circuit, which is the same operation as the item A) described in the embodiment shown in FIG. 2 marked with 011. B) When operating other actuators that require independence at the same time as straight traveling, for example, the arm switching valve 4
In conjunction with the operation b, the auxiliary switching valve 21 is switched to the B position, and the pressure oil is guided to the operating part of the switching valve 6 through the pipe 22 via the FIli auxiliary switching valve 21, and the switching valve 6 is switched to the position B. Therefore, B) in the embodiment of FIG. 2 described above.
It will be in the same state as the section above, and will operate in the same way as explained in the section. This also applies to actuators other than the arm. C) Set the left travel direction switching valve 4d to state A (or B)
When the right direction 9J switching valve 5c is set to B (or A), IJ of the pilot pump 11:, i+
1+ is traveling hli IJJJ through J exchange valve 15.
The pilot is guided to the line 18 (v), but the travel assist switching valve I6 is blocked, so the pilot is not guided to the line 20, and the switching valve 6 is not switched. Therefore, it has the same function as a conventional hydraulic circuit. D) Even when one side of the vehicle is operated, as explained in section C) of the embodiment shown in FIG.
:It's the same plane as the li'jl road, 1'7hi. (Effects of the Invention) The hydraulic circuit of the present invention has j4. + (Considering that, when operating other actuators other than traveling while traveling straight ahead, the switching valve must be changed 9). Pressure oil is distributed evenly to the left and right travel motors independently from other actuators, and pressure oil from the other hydraulic pump is supplied to various actuators other than travel with priority given to travel. While traveling straight without meandering, various actuators other than traveling can be operated reliably, ensuring efficient work.

[Brief explanation of drawings]

Figure 1 shows a conventional hydraulic circuit. FIG. 2 shows an embodiment circuit of the present invention. FIG. 3 also shows the circuit of the second embodiment. In the figure: ] First hydraulic pump 2 Second hydraulic pump 3 Prime mover 4 First directional valve group 4a Directional switching valve for swing 4b Directional switching valve for arm 4c Second boom directional switching valve 4d Directional switching for human rotation Valve 4e Load check valve 4f Throttle 5 Second direction switching valve group 5a First boom direction switching valve 5b Directional switching valve 5c for right-hand drive direction switching valve 5d Load check valve 5e Throttle 6 First switching valve r 7 ',''H゛Road 8 Bench/Road 99''i°Road 10 Ri n''Road 11 Bi-U Notopo'' Nb 12 Relief Valve 1 Co. 3 Relief Valve 14 Relief Valve 15 Travel Assist Switching Valve 16 Travel Assist Switching Valve 17
Pipe line 18 Pipe line 19 Pipe line 20 Pipe line 21 Auxiliary switching valve

Claims (1)

[Scope of Claims] (1) Direction and direction of pressure oil supplied to two hydraulic pumps, a first hydraulic pump and a second hydraulic pump, and a plurality of actuators driven by pressure oil from these hydraulic pumps. In the hydraulic circuit of a hydraulic excavator or the like, which is equipped with a plurality of directional switching valves divided into a first directional switching valve group and a second directional switching valve group that control the flow rate,
The first directional valve group is connected in parallel in random order to at least one of the swing directional valve, the arm directional valve, the second boom directional J valve, etc., and the one-force travel directional valve. The second directional valve group is connected in tandem to the parallel passage connected to one travel directional valve through a throttle and funnel check valve, and the second directional valve group is connected to the first boom directional valve and the bucket directional valve. At least one of the directional switching valves etc. and the other directional switching valve for running are connected in parallel in random order, and connected in tandem to the parallel passage connected to the other directional switching valve for running via a throttle and load check valve, Said 1st. Between the second hydraulic pump and the group 7 of the 1st and 2nd directional valves. The pressure oil from the second hydraulic pump is transferred to the first hydraulic pump.゛A condition in which pressure oil from the first hydraulic pump can be supplied between the upstream of the second directional control valve group, the traveling direction control valve, and the load check valve, respectively, and the pressure oil from the first hydraulic pump is supplied to the first and second directional control valves. Oil 1-, characterized in that a switching valve capable of switching between the traveling direction switching valve and the load check valve of the directional switching valve group is provided so that the supply is possible.
Hydraulic circuit for construction machinery such as E-excavators. (11) A directional switching valve for left and right running, an auxiliary switching valve for running layer that moves +lI4, and an auxiliary switching valve that is linked with an actuator that creates independence with λ = 1 for running are provided, and the directional switching valve for left and right running is provided. When at least one actuator that switches in the same direction and provides curvature independence for travel is operated, pressure oil is transferred from the pilot pump to the pilot boat of the switching valve via the travel auxiliary switching valve and the auxiliary switching valve. IWl of the patent claim, which is characterized in that it leads to
) Hydraulic circuits for construction machinery such as hydraulic lifts.