JPH0643259Y2 - Hydraulic equipment for construction machinery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a hydraulic system for a construction machine, such as a hydraulic excavator, which enables a vehicle to go straight even when a working machine system actuator is driven while the vehicle is going straight. .

[Conventional technology]

This type of hydraulic system is, for example, the hydraulic circuit described in JP-A-61-165429. This hydraulic circuit, as shown in FIG.
The pump 101 is connected to the pilot switching valve 103 via the passage 102, and at the position a, the pilot switching valve 103 is connected to the traveling switching valve 105 of one circuit system A via the passage 104, and the pilot switching valve 103 is connected to the pilot switching valve 103. When switched to the position b, it is connected to the parallel passage 108 of the circuit system A and the parallel passage 109 of the circuit system B via the check valves 106 and 107.

The other pump 111 is always connected to the traveling switching valve 113 of the circuit system B via the passage 112, and is also connected to the pilot switching valve 103 via the branch passage 114 branched from the passage 112. The switching valve 103 is blocked at the position a, but is connected to the traveling switching valve 105 of the circuit system A at the position b.

The pilot chamber 115 of the pilot switching valve 103 has an opening / closing valve.
When the valves 116 and 117 are closed, or when the open / close valves 116 and 117 and the open / close valves 118 to 123 are open, the pressure oil from the pilot pump 124 escapes to the tank 125, and the pilot pressure is not guided to the pilot chamber 115. Therefore, the pilot switching valve 103 assumes the position a. On the other hand, the on-off valves 116 and 117 are opened and the on-off valves
When any of 118 to 123 is closed, the pilot pressure on the valve closing side is introduced into the pilot chamber 115 via the shuttle valve 126, and the pilot switching valve 103 switches to the position b.

The on-off valves 116 and 117 are the switching valves 105 and 113 for traveling and the on-off valve 11
8 to 123 are interlocked with the working machine changeover valves 127 to 132, and when the traveling changeover valves 105 and 113 take the functional positions, the on-off valves 116 and 117 are closed to open, and the working machine changeover valves 127 to 132 are set to the neutral position. When taken, the on-off valves 118 to 123 are configured to change from valve closed to valve open.

Therefore, when only the traveling switching valves 105 and 113 are switched to the functional position, the pilot switching valve 103 takes the position a,
The oil discharged from the pump 101 is transferred from the travel switching valve 105 to the hydraulic motor 13
The oil discharged from the pump 111 is guided to the hydraulic motor 134 from the traveling switching valve 113.

Also, when the traveling switching valves 105 and 113 are held in the neutral position and any of the working machine switching valves 127 to 132 is switched to the functional position, pilot pressure is not guided to the pilot switching valve 103, so pilot switching is performed. The valve 103 assumes the position a. In this case, the oil discharged from one pump 101 is the pilot switching valve 103,
From the passage 104 to the traveling switching valve 105, the working machine switching valve 12
7 to 129 escape to the tank 125 through the center bypass passage in the neutral position, and the discharge oil of the other pump 111 reaches the traveling switching valve 113 from the passage 112, and, for example, the working machine switching valve 131 switches to the functional position. Then, it is supplied from the parallel passage 109 to the working machine actuator via the working machine switching valve 131.

Next, if any of the working machine switching valves 127 to 132 and the traveling switching valves 105 and 113 are switched to the functional positions, the pilot switching valve 103 is switched to the position b as described above, and the oil discharged from the pump 111 is supplied to the passage. Dividing into 112 and 104 and switching valve for traveling 105,113
Is supplied to the hydraulic motors 133 and 134, and the pump 101
Oil is diverted at the check valves 106 and 107 and supplied to the parallel passages 108 and 109, and the traveling motors 133 and 134 whose drive source is different from that of the working machine system actuator are normal without being affected by the load of the working machine system actuator. It operates in the state and can avoid the meandering of the vehicle.

[Problems to be solved by the device]

By the way, when the working machine is not used while the vehicle is traveling, the discharge oil of the pump 101 is guided to the traveling motor 133 and the traveling motor 13
Although the discharge oil of the pump 111 is guided to the pump 4, when any of the working machine switching valves 127 to 132 is switched to the functional position, the pilot switching valve 103 is switched to the position b and the pump 111 is discharged.
Oil is supplied to both traveling motors 133 and 134, and the oil discharged from pump 101 is supplied to the actuator for the working machine through a switching valve having a functional position, so the amount of oil supplied to traveling motors 133 and 134 is halved at once. At that time, a shock occurs in the traveling motor.

Further, in JP-A-61 142235, the switching valve 5e is switched to the position B when the working machine is used while the vehicle is running, and in the second embodiment, the throttle and the check valve provided in the switching valve 5e, the third valve. In the embodiment, the throttle and the check valve that connect the parallel passage and the neutral passage allow the surplus pressure oil supplied to the actuator for the working machine to travel to the left and right only when the oil pressure is higher than the oil pressure of the traveling motor. It can be supplied to the motor. However, when the load of the working machine is light, the pump pressure supplied to the working machine cannot be increased, and the operability of the working machine and the vehicle traveling is not good. Further, if the working machine with a light load is operated while the vehicle is traveling, the amount of oil to the traveling motor is reduced by half at a stroke, causing a shock to the traveling motor.

The present invention has been made in view of the above points, and it is possible to reduce the shock of the traveling motor when the actuator for the working machine is operated while the vehicle is traveling, and to reliably operate the working machine and the vehicle. The purpose of the present invention is to provide a hydraulic system for a construction machine that can be used for

[Means for Solving the Problems]

The structure of the present invention for achieving this object will be described with reference to FIG.

Two sets of circuit systems are provided, and each circuit system is connected in tandem with the most upstream travel switching valve connected to the pump and a plurality of working machine switching valves connected in parallel passages. In the hydraulic system of the construction machine, the actuator is controlled by the traveling switching valve of both circuit systems, the pilot switching valve connecting the parallel passage and the pump, and the switching valve of the actuator, and one circuit system (B) Connect the pump to the travel switching valve and the pilot switching valve, and connect the parallel passage to the pilot switching valve via the throttle valve. In the other circuit system (A), connect the pump to the parallel passage via the throttle switching valve. And the upstream of the switching valve for throttle and the upstream of the switching valve for traveling are connected to the pilot switching valve. The pilot pressure is guided only when one traveling switching valve and at least one working machine switching valve are in the functional position. The pilot switching valve is the other circuit system when the pilot pressure does not act. When the pump of (A) communicates with the travel switching valve, and the travel switching valve communicating with the pump of one circuit system (B) and the parallel passage are cut off from each other and the pilot pressure acts, Together with the switching valve with switch, the two switching valves for traveling are communicated with each other, and the communication passage is connected through the throttle in the pilot switching valve to the pump of the other circuit system (A) and one circuit system ( Connected to the parallel passage connected to the throttle valve of B), the switching valve with throttle cuts off the pump of the circuit system (A) and the parallel passage when the pilot pressure does not act,
It is characterized in that it is configured to be connected via a throttle 59 when a pilot pressure acts.

A fixed throttle may be used instead of the switching valve with throttle.

[Action]

When only the traveling motors 8 and 27 are driven by the operation of the traveling switching valves 3 and 6, the pilot pressure does not act on the pilot switching valve 2, so that the discharge oil of the pump 1 is supplied to the traveling motor 8 and the pump 4. The discharged oil is supplied to the traveling motor 27. When any one of the working machine switching valves 10, 12, 15, 29, 31, 33 is switched from the neutral position to the functional position, the pilot switching valve 2 and the throttled switching valve 21 are switched to the position B by the pilot pressure. Then, the pump 4 communicates with the traveling switching valves 3 and 6, and the pump 1
Is in the parallel passage 19 via the throttle 59 of the switching valve with throttle 21,
Further, it is connected to the parallel passage 37 via the throttle valve 40, and is also connected to the pump 4 and both traveling switching valves 3 and 6 via the throttle 58 of the pilot switching valve 2. Therefore, for example, when operating one of the working machines while the vehicle is traveling, even if the load of the working machine is light, the pressure of the discharge passage of the pump 1 is kept high (appropriately) and the discharge oil of the pump 4 is maintained. It is possible to reliably operate the working machine and the vehicle traveling by preventing the oil from flowing out to the working machine side, and at the same time, to guide the excess oil of the pump 1 to the traveling switching valves 3 and 6 and Since the traveling motors 8 and 27 are driven by merging with the discharged oil, the shock of the traveling motor due to the operation of the working machine can be reduced and the traveling speed is improved.

〔Example〕

An embodiment of the present invention will be described with reference to the drawings. In FIG. 1, a pump 1 is connected to a pilot switching valve 2 and a throttled switching valve 21 of one circuit system A, and a pump 4 is connected to a most upstream running switching valve 6 of the other circuit system B by a passage 5. At the same time, the branch passage 7 branched from the passage 5 is connected to the pilot switching valve 2.

In one circuit system A, a traveling switching valve 3 for sequentially controlling the traveling motor 8 from the upstream side, a working machine switching valve 10 for controlling the boom cylinder 9, a working machine switching valve 12 for controlling the bucket cylinder 11, A working machine switching valve 15 connected to the arm cylinder 13 by a merging circuit 14 is provided, and the traveling switching valve 3 and the working machine switching valves 10, 12, 15 are connected in tandem, and the switching valve 3,
When 10, 12, 15 are in the neutral position, the center bypass passage 22 is opened so that the oil discharged from the pump 1 is released to the tank 24, and the working machine switching valves 10, 12, 15 are check valves 16, 17, 18 Connected by parallel passage 19 equipped with. The parallel passage 19 is connected to a passage 20 connecting the traveling switching valve 3 and the pilot switching valve 2 upstream of the traveling switching valve 3 via a pilot operated throttled switching valve 21, and the traveling switching valve 3 and the working machine switching valve. It is connected to the center bypass passage 22 portion between 10 and 10 via a check valve 23.

In the circuit system B, a traveling switching valve 6 that controls the traveling motor 27 sequentially from the upstream side, a working machine switching valve 29 that controls the arm cylinder 13, and a working machine switching valve 3 that controls the swing motor 30.
1. A working machine switching valve 33 connected to the boom cylinder 9 by a merging circuit 32 is provided, and the traveling switching valve 6 and the working machine switching valve are provided.
29, 31, 33 are connected in tandem, and when the switching valves 6, 29, 31, 33 are in the neutral position, the center bypass passage 38 is opened so that the oil discharged from the pump 4 is released to the tank 24. The machine switching valves 29, 31, 33 are connected by a parallel passage 37 equipped with check valves 34, 35, 36. The parallel passage 37 is a center bypass passage 38 between the traveling switching valve 6 and the working machine switching valve 29.
It is connected to the part via check valve 39, and throttle valve 40
It is connected to the pilot switching valve 2 via.

The pilot chamber 41 of the pilot switching valve 2 is a pilot oil passage.
It is connected to the pilot pump 43 by 42 and is also connected to the pilot chamber 45 of the throttled switching valve 21 via the pilot oil passage 44 branched from the pilot oil passage 42. The pilot oil passage 42 is connected to the pilot oil passage 52 in which the open / close valves 46, 47, 48, 49, 50, 51 provided on the working machine switching valves 10, 12, 15, 33, 31, 29 are connected in tandem, and the pilot oil passage 42 The switching valves 53, 54 provided in the switching valves 3, 6 are connected to the pilot oil passage 55 connected in tandem. The pilot oil passage 52 connects the pilot pump 43 to the tank 24 when the working machine switching valve 10, 12, 15, 33, 31, 29 in which the open / close valves 4647, 48, 49, 50, 51 are opened is in the neutral position. Communication, pilot oil passage
55 connects the pilot pump 43 to the tank 24 when the traveling switching valves 3 and 6 are in the neutral position where the opening / closing valves 53 and 54 are opened.

When the pilot pump 43 communicates with the tank 24, the pilot switching valve 2 and the throttled switching valve 21 are pushed by the springs 56 and 57 to take the position a. When the pilot switching valve 2 is in the position a,
The pump 1 is connected to the traveling switching valve 3 of the same circuit system A, the branch passage 7 connected to the pump 4 and the upstream of the throttle 40 are cut off from each other, and the throttled switching valve 21 is connected to the pump 1 at the position a. The communication with the parallel passage 19 is cut off. When the communication between the pilot pump 43 and the tank 24 is cut off, the pilot pressure of the pilot pump 43 acts on the pilot switching valve 2 and the throttled switching valve 21, and both switching valves are switched to the position b. When the pilot switching valve 2 is in the position b, the branch passage 7 of the pump 4 is
Is connected to the traveling switching valve 3, the pump 1 is connected to the parallel passage 37 via the throttle valve 40, and is connected to the passage 20 and the branch passage 7 via the throttle 58 of the pilot switching valve 2. When the switching valve with throttle 21 is in position b, the pump 59 is operated by its throttle 59.
And connect the parallel passage 19.

When the traveling switching valves 3 and 6 are switched to the functional position a in the neutral state in the figure, the pilot oil passage 55 is blocked by the opening / closing valves 53 and 54, but the pilot oil passage 52 communicates with the tank 24. Therefore, the pilot pressure is not generated, and the pilot switching valve 2 and the throttle switching valve 21 are at the position a. This allows
The oil discharged from the pump 1 passes through the travel switching valve 3 and travel motor 8
The discharge oil of the pump 4 flows into the traveling motor 27 through the traveling switching valve 6, and the return oil of the traveling motors 8 and 27 passes through the traveling switching valves 3 and 6 and the return lines 60 and 61 to the tank 24. The traveling motors 8 and 27 are driven by dedicated pumps 1 and 4, respectively, and the vehicle goes straight.

During traveling of the vehicle, when the switching valve 31 for the working machine, for example, the switching valve 31 for controlling the swing motor 30 is switched from the neutral position to the functional position, the opening / closing valve 50 is closed and the pilot pump 43 is disconnected from the tank 24. The switching valve 2 and the switching valve with throttle 21 are switched to the position b by the pilot pressure of the pump 43. As a result, the branch passage 7 communicates with the passage 20, the discharge oil of the pump 4 is distributed to the traveling switching valves 3 and 6, and the discharge oil of the pump 1 is distributed to the throttle valve 40, the parallel passage 37, and the working machine switching valve 31. Is supplied to the swivel motor 30 via, and the surplus oil is distributed to the traveling switching valves 3 and 6 through the throttle 58 of the pilot switching valve 2. In this case, the switching valve with throttle 21 is also switched to the position b, but since the switching valves 10, 12 and 15 are all in the neutral position, the discharge oil of the pump 1 does not flow to the parallel passage 19.
Therefore, the traveling motors 8 and 27 are distributed with the amount of oil obtained by subtracting the amount of oil supplied to the swing motor 30 from the total amount of oil discharged from the pumps 1 and 4, and the oil pressure of the pump 1 is then distributed to the throttle valve 40 and the throttle 58. It can be enhanced.

When any one of the working machine switching valves 10, 12, 15 of the circuit system A is switched from the neutral position to the functional position while the vehicle is traveling, the discharge oil of the pump 4 is the switching valve for traveling as in the previous case. The discharge oil of the pump 1 is distributed to 3 and 6, and is supplied to the actuator via the throttle 59 of the switching valve with throttle 21, the parallel passage 19 and the switching valve, and the surplus is passed through the throttle 58 of the pilot switching valve 2. Then, it is distributed to the traveling switching valves 3 and 6.

Next, for example, the switching valve for driving the working machine actuator when the vehicle is stopped when the traveling switching valves 3 and 6 are in the neutral position.
When 29 is switched from the neutral position to the functional position, the working machine switching valve 15 interlocking therewith is also switched from the neutral position to the functional position, and the pilot oil passage 52 is blocked by the opening / closing valves 51, 48. However, since the pilot pump 43 communicates with the tank 24 through the oil passage 55, the pilot switching valve 2 and the switching valve with throttle 21 are in the position A, and the oil discharged from the pump 4 is transferred from the traveling switching valve 6 to the check valve 39. , 34 through the work machine switching valve 29 and then into the arm cylinder 13, and the discharge oil of the pump 1 passes from the pilot switching valve 2 to the traveling switching valve 3, the check valve 23, and the check valve 18 of the parallel circuit 19 for work. While flowing into the arm cylinder 13 through the machine switching valve 15 and the confluent passage 14, the return oil of the arm cylinder 13 returns to the tank 24 through the working machine switching valves 29, 15 and the return lines 61, 60, and the arm cylinder 13. 1
Activate 3.

Even if a fixed throttle is used in place of the throttle-equipped switching valve 21 provided between the pump 1 and the parallel passage 19, the same effect as described above can be obtained. Further, the pilot switching valve 2 and the throttled switching valve 21 may be mechanically interlocked.

[Effect of device]

As described above, according to the present invention, when the working machine actuator is driven by the working machine switching valve operation while the vehicle is traveling, one pump is connected to the parallel passages of both circuit systems through the respective throttles, Also, throttle of pilot switching valve 2
Since it is connected to both travel switching valves via 58, the discharge pressure of the pump that supplies the discharge oil to the work machine is kept high (appropriately) even when the load on the work machine is a light load, and By preventing a part of the oil discharged from the pump from flowing out to the work machine side, the operation of the work machine and the operation of the vehicle can be reliably performed, and the excess oil of the pump that supplies the discharge oil to the work machine is Since the discharge oil of the other pump that leads to both travel switching valves joins, the shock of the travel motor due to the operation of the working machine while the vehicle is traveling can be reduced, and the traveling speed can be improved.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of an embodiment of the present invention, and FIG. 2 is a hydraulic circuit diagram of a conventional device. A, B …… Circuit system, 1,4 …… Pump, 2 …… Pilot switching valve, 3,6 …… Running switching valve, 7 …… Branch passage, 10,12,1
5,29,31,33 …… Work machine switching valve, 19,37 …… Parallel passage, 21 …… Throttle switching valve, 40 …… Throttle valve, 42,52,55 ……
Pilot passage, 46,47,48,49,50,51,53,54 …… Open / close valve, 58,59 …… Throttle.

Claims (2)

[Scope of utility model registration request] 1. A set of two circuit systems, each circuit system having a switching valve for traveling at the most upstream connected to a pump and a plurality of working machine switching valves connected in parallel passages through a center bypass passage. In a hydraulic system of a construction machine, which is connected to a tandem via a pilot switching valve connected to a traveling switching valve of both circuit systems, a parallel passage and a pump, and the switching valve of the actuator, to control the actuator,
In one circuit system (B), the pump (4) is connected to the traveling switching valve (6) and the pilot switching valve (2), and the parallel passage (37) is connected to the pilot switching valve () via the throttle valve (40). 2), and in the other circuit system (A), the pump (1) is connected to the parallel passageway (19) via the throttled switching valve (21) and travels upstream of the throttled switching valve (21). The pilot switching valve (2) and the switching valve with a throttle (21) are connected to the upstream of the switching valve (3) for the pilot switching valve (2).
Is configured such that the pilot pressure is introduced only when at least one traveling switching valve and at least one working machine switching valve are in the functional position. The pilot switching valve (2) is operated by the pilot pressure. When not doing, while connecting the pump (1) of the other circuit system (A) to the traveling switching valve (3),
When the traveling switching valve (6) communicating with the pump (4) of the one circuit system (B) and the parallel passage (37) are cut off from each other and the pilot pressure acts, the switching valve with throttle (2
1) and switching to the position (b), the two switching valves (6) and (3) for communication are communicated with each other, and the communication passage is connected to the other circuit via the throttle (58) in the pilot switching valve (2). System (A)
Connected to a parallel passage connected to the pump (1) of FIG. 1 and the throttle valve (40) of one circuit system (B), and the switching valve with throttle (21) is connected to the pump (1) of the circuit system (A) and the parallel passage (19). ) Is disconnected when the pilot pressure does not act, and is connected via the throttle 59 when the pilot pressure acts, the hydraulic system for the construction machine. 2. The hydraulic system for a construction machine according to claim 1, wherein the switching valve with throttle (21) is a fixed throttle.