JP4118893B2 - Hydraulic circuit - Google Patents

Description

The present invention relates to a hydraulic circuit that supplies pressure oil to a plurality of actuators and the like, and relates to a hydraulic circuit that is used in a construction machine such as a crawler vehicle including a plurality of actuators such as a hydraulic excavator.

A construction machine such as a crawler vehicle including a traveling device and a plurality of actuators is provided with an auto-idle function for controlling the rotational speed of a drive source in accordance with the operation state of the construction machine.

For this reason, a circuit for taking out an auto idle signal for detecting the operation state of each actuator for the auto idle function is provided.

On the other hand, a safety device such as a light or a siren may be provided to inform the surrounding people that the construction machine is traveling.

Also in this case, the hydraulic circuit used in the construction machine described above is provided with a circuit for extracting a traveling signal for detecting the operation state of the traveling device in order to operate the safety device.

As a circuit for extracting the travel signal, it is conceivable that a pilot valve is separately provided in the direction switching valve for the traveling device, but the travel direction switching valve is enlarged accordingly.

An object of this invention is to suppress that the hydraulic circuit used in the construction machine provided with the safety device and the auto idle function enlarges.

Means and effects for solving the problems

A hydraulic circuit according to a first aspect of the present invention that solves the above problem includes a safety device that informs the surroundings that the vehicle is running, and an auto-idle function that controls the rotational speed of the drive source in accordance with the operating state of each actuator. A directional control valve for traveling, which is used in a construction machine and controls a connection direction and a flow rate of a hydraulic pump or tank and a traveling device; a connection direction and a flow rate of an actuator other than the pump or tank and the traveling device; Another direction switching valve for controlling the vehicle, a traveling signal oil passage for generating a traveling signal when the traveling direction switching valve is operated, and an auto idle signal is generated when the other direction switching valve is operated. An automatic idle oil passage, and the rotational speed of the drive source is controlled based on the travel signal oil passage and the automatic idle oil passage.

According to this configuration, the signal generating oil passage for the auto idle function is separated into the traveling direction switching valve and the other direction switching valve, and the traveling signal oil passage is used for the safety device and the auto idle. Therefore, it is not necessary to provide a pilot passage or sub valve only for the safety device, and it is possible to prevent the direction switching valve from becoming enlarged.

Hereinafter, a hydraulic circuit according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 illustrates this embodiment, FIG. 3 illustrates a modification, and FIG. 5 illustrates a construction machine in which the hydraulic circuit of the present invention is used.

(Example)
The hydraulic circuit 1 according to the present embodiment is used in, for example, a construction machine such as a mini excavator 150 having a plurality of hydraulic actuators as shown in FIG. 5, and each hydraulic actuator and each pump or tank as shown in FIG. And a plurality of directional control valves (11 to 19) for controlling the connecting direction and the flow rate of the pressure oil.

1 and 5, the direction switching valves 11 to 19 have actuator ports A1 to A7 connected to the respective actuators of the mini excavator 150 shown in FIG.
, A9-10, B1-8, B10. Some of the actuators corresponding to each direction switching valve are shown in FIG. 1, and referring to this, the direction switching valve 11 is for a cylinder 22 connected to a boom swing actuator (not shown). Is for the cylinder 24 connected to the dozer 23, the direction switching valve 13
Is for a hydraulic motor (not shown) for driving the swivel base 33 (swing actuator), the direction switching valve 14 is a spare (service) and is not used, and the direction switching valve 15 is for the arm cylinder 26 of the arm 25, The direction switching valve 16 is for a hydraulic motor (not shown) that drives the left traveling device 27, the direction switching valve 17 is for a hydraulic motor (not shown) that drives the right traveling device 28, and the direction switching valve 18 is the boom 29. The boom cylinder 30 and the direction switching valve 19 are for the bucket cylinder 32 of the bucket 31.

By operating each of these direction switching valves 11 to 19, the connection direction of the return and return of the pressure oil to each actuator is switched, and each actuator is operated. The direction switching valves 11, 12, 14, 16, and 17 are manually operated direction switching valves, and the direction switching valves 13, 15, 18, and 19 are remote control operated direction switching valves.

In FIG. 1, the hydraulic circuit 1 is supplied with pressure oil from three pumps (first to third pumps) (not shown). The first pump 3 is a pump port P1 and the second pump 4 is a pump. At the port P2, the third pump 5 is connected to the hydraulic circuit 1 at the pump port P3.

And the hydraulic circuit 1 is provided with three circuits (1st circuit a, 2nd circuit b, 3rd circuit c) by the connection structure with each pump to which pressure oil is supplied. First, the first circuit a includes directional control valves 17, 18, and 19 that are supplied with pressure oil from the first pump 3 through the pump port P <b> 1 and are connected to the first unload passage 34. The right traveling direction switching valve 17 is disposed on the most upstream side of the first unload passage 34, and other direction switching valves (18, 19) other than the right traveling direction switching valve 17 are disposed on the downstream side thereof. Has been. These directional control valves 17, 18, and 19 are configured to receive pressure oil supply from the first unload passage 34 through passages 45, 46, and 47, respectively. The tanks 35 communicate with the tank passages 35 through the discharge passages 48, 49, and 50. The most downstream side of the first unload passage 34 also communicates with the tank passage 35. The tank passage 35 communicates with the tank 36 via tank ports T1 and T2.

Next, the second circuit b includes directional control valves 14, 15, and 16 that are supplied with pressure oil from the second pump 4 through the pump port P <b> 2 and are connected by the second unload passage 38. The left traveling direction switching valve 16 is disposed on the most upstream side of the second unload passage 38, and other direction switching valves (15, 14) other than the left traveling direction switching valve are disposed downstream thereof.
) Is arranged. Further, the direction switching valves 15 and 16 other than the standby are supplied with pressure oil even if they pass through the passages 51 and 52 from the second unload passage 38 and communicate with the tank passage 35 through the discharge passages 53 and 54, respectively. ing. Further, the most downstream side of the second unload passage 38 communicates with the tank passage 35 in the same manner as the first unload passage 34.

A supply switching valve 21 is connected between the first pump 3 and the second pump 4 and the first circuit a and the second circuit b. The supply switching valve 21 is connected to the tank passage 35.
To the operation position 21 from the unload position 21a communicating with the passages 70 and 71.
By switching to b, the first circuit 3 and the second pump 4 are switched from the first pump 3 and the second pump 4 to the second circuit 4.
Pressure oil can be supplied to the circuit b. From the unload position 21a to the operation position 21
Switching to b is performed by the pilot pressure oil from the pilot pump 7 acting on the pilot pressure receiving portion 40 of the supply switching valve 21 via the pilot port Pp2 and the pilot oil passage 39. Incidentally, this pilot pressure signal will be described later.

Finally, the third circuit c is supplied with pressure oil from the third pump 5 through the pump port P3, and is connected to the third unload passage 42 through the supply passage 41.
1, 12, and 13 are provided. The direction switching valves 11, 12 and 13 are connected in this order from the upstream side of the third unload passage 42, and the downstream side of the most downstream side turning direction switching valve 13 is connected to a merging valve 20 which will be described later. Further, passages 55 and 56 are connected from the supply passage 41 to the direction switching valves 12 and 13, respectively, and the direction switching valves 11, 12 and 13 are connected to the tank passage 3 through the discharge passages 57, 58 and 59, respectively.
5 communicates.

Further, in the third circuit c, a passage 60 that branches from the supply passage 41 leading to the upstream side of the third unload passage 42 to the tank passage 35 via the relief valve 43 is branched. The supply passage 6 leading to the merging valve 20 also from the middle of the passage 60
1 is branched. The supply passage 61 further branches into two and communicates with the junction valve 20.

The junction valve 20 communicates with the third pump 5 through the aforementioned supply passage 61 and also communicates with the tank passage 35 through the discharge passage 62. Further, the merging valve 20 has a first merging passage 65 and a second merging passage 66 via check valves 63 and 64, respectively.
Is connected. The first merge passage 65 communicates with the first circuit a, and the second merge passage 66.
Is in communication with the second circuit b.

The first merging passage 65 communicates with other direction switching valves 18 and 19 other than the right traveling direction switching valve 17 in the first circuit a via passages 46 and 67, respectively. The passage 67 is provided with a throttle 68 in the middle so that pressure oil can be supplied to the boom direction switching valve 18 with priority over the bucket direction switching valve 19.

The second junction passage 66 communicates with other direction switching valves 14 and 15 other than the left travel direction switching valve 16 in the second circuit b via passages 51 and 69, respectively. The passage 51 also merges with the second unload passage 38.

Next, the merging valve 20 causes the third pump 5, the first merging passage 65, and the second
A switching configuration for communicating with or blocking the merging passage 66 will be described.

The merging valve 20 includes an unloading position 20a, a first switching position 20b, and a second switching position 2.
0c and a running position 20d, and four switching positions are provided. As will be described later, the pilot pressure command acts on the pilot pressure receiving portions 72, 73, and 74, so that the merging valves are the first switching position 20b and the second switching position, respectively. The position is switched to the switching position 20c and the running position 20d. The first switching position 20b and the second switching position 20c are switched proportionally / stepwise according to the pressure of the pilot pressure receiving unit 73.
Hereinafter, in addition to FIG. 1, each switching position will be described in turn with reference to FIG. 2, which is an enlarged circuit diagram of the junction valve 20.

First, the unloading position 20a is a position held by the spring 75 when pilot pressure is not supplied to the pilot pressure receiving portion 72 by a valve (not shown). The unloading position 20a communicates one of the supply passages 61a with the tank passage 35, shuts off the other supply passage 61b, and passes the third unload passage 42 on the downstream side of the turning direction switching valve 13 to the second junction. It communicates with the passage 66.
The second merge passage 66 communicates with the second unload passage 38.

Next, the first switching position 20 b is switched by supplying pilot pressure to the pilot pressure receiving part 72. The pilot pressure oil acts on the pilot pressure receiving part 72 through the pilot oil passage 76 from the pilot port Pp1. Pilot oil passages 79 and 80 are communicated with the pilot oil passage 76. However, since the pilot oil passages 79 and 80 communicate with each other through the throttles 77 and 78, respectively, the pressure of the pilot pressure receiving portion 72 does not decrease, and the unloading is performed. The position is switched from the position 20a to the first switching position 20b.

The pilot oil passage 79 is used for switching the pilot pressure oil to the traveling position 20d by applying the pilot pressure oil to the pilot pressure receiving portion 74, which will be described later. The oil passage 80 is connected to the sub-valves 13s and 15s of the direction switching valves 13 and 15, and is communicated or blocked by these sub-valves. The most downstream side of the oil passage 80 is a tank passage. 35 is communicated. And
When at least one of the direction switching valves 13 or 15 is switched, the oil passage 80 is shut off, and pressure oil is supplied to the oil passage 81 branched from the oil passage 80, and the turning negative (
Brake release pressure) is taken out (see FIG. 1).

The first switching position 20b blocks both of the two supply passages 61a and 61b to which pressure oil is directly supplied from the third pump 5, and the downstream side of the third unload passage 42 leads to the second merge passage 66. Communicate. That is, the excess pressure oil of the pressure oil supplied from the third pump 5 to the direction switching valves 11 to 13 of the third circuit c is supplied to the direction switching valves 14 and 15 of the second circuit b through the second junction passage 66. Will be.

Next, the second switching position 20c will be described.
In the second switching position 20c, one of the supply passages 61a is communicated with the first joining passage 65 via the communication passage 84 provided with the restriction 83, and further branched from the communication passage 84 to be provided with the restriction 85. It also communicates with the second merging passage 66 via the passage 87. The other supply passage 61b is kept shut off. And the third unload passage 42
The downstream side is communicated with the communication passages 84 and 87 via the communication passage 86, and the first merge passage 65 is communicated with the second merge passage 66 via the restriction 85 without the restriction.

The merging valve 20 moves proportionally / stepwise between the first switching position 20b and the second switching position 20c according to the pressure of the pilot port Pa8 ′. The pilot port Pa8 ′ is a direction switching valve 18 that commands the boom raising operation of the boom cylinder 30.
Is the pilot pressure sent to the pilot port Pa8.
Thus, when the direction switching valve 18 is not operated, the merging valve 20 is
The pressure oil which is located at the switching position 20b and is pumped to the third circuit c is not supplied to the first circuit a where the direction switching valve is not operated, but to the second circuit b where the pressure oil needs to be supplied When the direction switching valve 18 is operated, the pressure oil from the third pump 5 can be supplied to the second circuit b and the first circuit a.

Furthermore, the merging valve 20 is between the first switching position 20b and the second switching position 20c.
If the pilot port Pa8 ′ moves proportionally / stepwise, for example, if the pilot pressure from a remote control valve (not shown) is increased to increase the raising speed of the boom cylinder 30, the direction is switched. The valve 18 moves to the position 18a side,
In accordance with this, the merging valve 20 also moves to the second switching position 20c side. Therefore, the second
The pressure oil sent to the circuit b decreases, and more pressure oil is sent to the first circuit a. In this way, the combined oil amount can be distributed to the first and second circuits a and b according to the oil amount required by the boom cylinder 30.

Further, the running position 20d of the merging valve 20 is a direction switching valve (11, 12) of the third circuit c.
13) from the upstream side of the first circuit a and the second circuit b through the restriction (83, 85) from the upstream side, and also from the downstream side of the direction switching valve (11, 12, 13) of the third circuit c. Since the first circuit a and the second circuit b are connected, the pressure oil pumped from the third pump 5 is supplied to the third circuit c while the pressure oil is supplied from the third pump 5 to the first circuit a and the second circuit. b, and a directional control valve (11, 12, 1) of the third circuit c.
The excess pressure oil discharged from the downstream side of 3) can also be pumped to the first circuit a and the second circuit b. Therefore, the pressure oil from the third pump 5 can be efficiently distributed to the first circuit a and the second circuit b without waste, and each actuator (25, 29, 3
The operability of 1) can also be improved.

The switching amount between the first switching position 20b and the second switching position 20c of the merging valve 20 is determined according to the pilot pressure of the pilot port Pa8, but the pilot of the pilot port Pa5 of the arm direction switching valve 15 is determined. The pressure and the operation of at least one or both of the boom direction switching valve 18 and the bucket direction switching valve 19 may be performed. Furthermore, the switching pressure of the merging valve 20 may be determined by comparing the load pressure of the boom cylinder 30 and the arm cylinder 26 and these pressures.

Finally, the running position 20d will be described. The running position 20d is connected to the supply passage 61.
One supply passage 61 a is connected to the first merging passage 65 via the first restrictor 91, and the other supply passage 61 b is connected to the second merging passage 66 via the second restrictor 94 and the communication passage 93. Further, the downstream side of the third merging passage 42 is connected to the first merging passage 65 through a communication passage 95 communicating with the communication passage 92.

Switching to the running position 20d is performed by supplying pilot pressure to the pilot pressure receiving unit 74. That is, the pressure oil sent from the pilot pump 6 through the pilot oil passage 76 is also sent to a part of the pilot oil passage 79 through the throttle 77. The pilot oil passage 79 is connected to the pilot pressure receiving portion 74 and branches to the oil passage 88. The oil passage 88 is connected to the sub valves 16 s, 17 s, 18 s, and 19 s provided in each of the direction switching valves 16, 17, 18, and 19 in this order, and the most downstream side communicates with the tank passage 35. is doing.

The sub valves 18 s and 19 s change the oil passage 88 from the communication state to the cutoff state by operating the direction switching valves 18 and 19, respectively. And the sub valve 16
In s and 17s, when the directional control valves 16 and 17 are operated, the oil passage 88 remains in communication, but the oil passage 89 or 90 is blocked.

By the configuration of these oil passages (79, 88, 89, 90), both the right traveling direction switching valve 17 and the left traveling direction switching valve 16 and the right traveling direction switching valve 17 in the first circuit a other than the right traveling direction switching valve 17 are provided. When at least one of the other directional control valves 18 and 19 is operated, the pilot pressure oil sent from the pilot pump 6 is supplied to the pilot pressure receiving portion 74.
And the merging valve 20 switches to the running position 20d.

When the traveling direction switching valve (16, 17) and the other direction switching valve (18, 19) other than the traveling direction switching valve are operated simultaneously by the configuration of the traveling position 20d,
The pressure oil pumped from the third pump 5 can be reliably supplied to the other direction switching valves (18, 19).
Furthermore, the running position 20d of the merging valve 20 is connected to the direction switching valve (11, 1) of the third circuit c.
2 and 13) from the upstream side of the first circuit a through the restrictor 91 and from the downstream side of the direction switching valve (11, 12 and 13) to the first circuit a through the passage 95. The pressure oil from the third pump 5 can be supplied to the first circuit a while supplying the pressure oil from the third pump 5 to the third circuit c, and the direction switching valve (1
Excess pressure oil discharged from the downstream side of 1, 12, 13) can also be pumped to the first circuit a. Therefore, the pressure oil from the third pump 5 can be efficiently distributed to the first circuit a and without waste, and the operability of each actuator (25, 29, 31) of the third circuit c can be improved.

Here, the traveling signal and auto idle signal extraction configuration provided in the hydraulic circuit 1 will be described.

A construction machine such as a crawler vehicle including a traveling device and a plurality of actuators is provided with an auto-idle function for controlling the rotational speed of a drive source in accordance with the operation state of the construction machine.

For this reason, a circuit for taking out an auto idle signal for detecting the operation state of each actuator for the auto idle function is provided.

On the other hand, a safety device such as a light or a siren may be provided to inform the surrounding people that the construction machine is traveling.

Also in this case, the hydraulic circuit used in the construction machine described above is provided with a circuit for extracting a traveling signal for detecting the operation state of the traveling device in order to operate the safety device.

As a circuit for extracting the travel signal, it is conceivable that a pilot valve is separately provided in the direction switching valve for the traveling device, but the travel direction switching valve is enlarged accordingly.

As will be described later, the hydraulic circuit 1 according to the present embodiment also suppresses the enlargement of a hydraulic circuit used in a construction machine having a safety device and an auto idle function.

That is, the hydraulic circuit 1 is used in a construction machine having a safety device that informs the surroundings that the vehicle is running and an auto idle function that controls the rotational speed of a drive source in accordance with the operation state of each actuator. Alternatively, a traveling direction switching valve that controls the connection direction and flow rate between the tank and the traveling device, and another direction switching valve that controls the connection direction and flow rate between the pump or tank and another actuator other than the traveling device. A travel signal oil passage that emits a travel signal by operating the travel direction switching valve, and an auto idle oil passage that generates an auto idle signal by operating the other direction switching valve. And a hydraulic circuit that controls the rotational speed of the drive source based on the travel signal oil path and the auto idle oil path.

In FIG. 1, the pilot pressure oil supplied from the pilot pump 7 through the pilot port Pp2 acts on the pilot pressure receiving portion 40 of the pilot operated supply switching valve 21 via the pilot oil passage 39, and automatically through the throttle 96. It is also supplied to the idle oil passage 97. The pilot oil passage 39 has a restriction 9
8, a running signal oil passage 99 is communicated.

The traveling signal oil passage 99 includes a switching valve communication oil passage 99a and the switching valve communication oil passage 99a.
And a travel signal extraction oil passage 99b branched from the road. The switching valve communication oil passage 99a is connected to each sub valve (16s, 17s) of the traveling direction switching valve (16, 17) and then communicates with the oil passage 90 to communicate with the tank passage 35. And
The travel signal oil passage 99b communicates with the travel signal extraction port PL.

In this way, the pilot pump 7 and each oil passage (35, 39, 40, 90, 98,
99) is connected, the construction machine (mini excavator 150) provided with the hydraulic circuit 1 can take out a traveling signal for lighting a safety device for informing the surroundings that the vehicle is traveling. That is, the pilot pressure oil that has flowed into the traveling signal oil passage 99 flows to the tank passage 35 through the switching valve communication oil passage 99a and the oil passage 90 when the traveling direction switching valves (16, 17) are not operated. . When at least one of the traveling direction switching valves (16, 17) is operated from this state, the mini excavator 150 starts traveling and the switching valve communication oil passage 99a.
Is cut off, pressure is generated in the travel signal extraction oil passage 99b, and the travel signal extraction port P
A running signal is generated at L. By applying this traveling signal to a pressure switch or the like for operating a safety device (not shown), a safety device for informing the surroundings that the mini excavator 150 is traveling is operated.

The auto idle oil passage 97 includes a switching valve communication oil passage 97a and an auto idle signal extraction oil passage 97b branched from the switching valve communication oil passage 97a.
The switching valve communication oil passage 97a includes sub-valves (19s, 1) of the other direction switching valves (19, 18, 15, 14, 13, 12, 11) other than the traveling direction switching valves (16, 17).
8s, 15s, 14s, 13s, 12s, 11s) in this order and communicated with the tank passage 35. The auto idle signal extraction oil passage 97b communicates with the auto idle signal extraction port Ai.

When none of the direction switching valves (11, 12, 13, 14, 15, 18, 19) is operated, the pressure oil partially flows from the pilot pump 7 into the oil passage 97 for auto idle through the throttle. Is connected to the tank passage 35 through the switching valve communication oil passage 97a.
It flows to. From this state, other directional control valves (11, 12, 13, 14, 15,
When at least one of 18, 19) is operated, the switching valve communication oil passage 97a is shut off, pressure is generated in the auto idle signal extraction oil passage 97b, and an auto idle signal is generated in the auto idle signal extraction port Ai. .

When neither the traveling signal nor the auto idle signal is generated using the traveling signal and the auto idle signal thus extracted, the rotational speed of the drive source is reduced to a predetermined value, and the traveling signal and the auto idle signal are If any of these occur, control is performed to increase the rotational speed of the drive source to a predetermined value.

As described above, the signal generating oil passage for the auto idle function is divided into the direction switching valve for traveling (16, 17) and the other direction switching valve (11, 12, 13, 14, 15, 18).
19), and this travel signal oil passage 99 is used for the safety device and the auto idle, so there is no need to provide a pilot passage or a sub-valve only for the safety device, and the direction switching valve 16 , 17 can be prevented from being enlarged.

(Modification)
Next, a hydraulic circuit 2 according to a modification relating to the structure of the hydraulic circuit to which the present invention is applied.
Will be described.
The hydraulic circuit 2 has substantially the same circuit configuration as the hydraulic circuit 1, and in FIG.
Corresponding elements have the same reference numerals as in FIG. The hydraulic circuit 2 and the hydraulic circuit 1 are different in the following three points. First, the first difference is that the position of the merging valve 20 is the unloading position 20a, the first switching position 20b, and the second switching position 20.
It is a point which is only three positions of c. In the merging valve 20 of the hydraulic circuit 2, the second switching position 20c also serves as a running position. The second difference is that the oil passage configuration communicating with the pilot pumps 6 and 7 is different. The third different point is that the para passage 51 connected to the arm direction switching valve 15 from the second merging passage 66 is
The point is that the second unload passage 38 is connected to the direction switching valve 15 without communicating with the second unload passage 38. Hereinafter, the first and second differences will be described in detail.

First, the first difference will be described with reference to FIG. 3 and an enlarged circuit diagram of the merging valve 20 in the hydraulic circuit 2 shown in FIG. As in the case of the hydraulic circuit 1, the merging valve 20 is configured to cut off the communication between the third pump, the first merging passage 65, and the second merging passage 66. As described above, the unloading position 20a, the first There are three switching positions, a switching position 20b and a second switching position 20c, and as described later, the pilot pressure command acts on the pilot pressure receiving parts (100, 101, 102, 103), so that the merging valves 20 are respectively 1st switching position 20b, 2nd switching position 2
It is switched to 0c, the second switching position (running position) 20c, and the first switching position 20b. Note that the first switching position 20b and the second switching position 20c are switched proportionally / stepwise in accordance with the pressures of the pilot pressure receiving portions 101 and 103.

  First, the unloading position 20a is the same as that of the hydraulic circuit 1.

Next, the first switching position 20 b blocks the two supply passages 61 a and 61 b to which pressure oil is directly supplied from the third pump 5, and the downstream side of the third unload passage 42 passes through the communication passage 111. It communicates with the second merging passage 66. The communication path 111 also branches from the communication paths 114 and 115 via the throttles 112 and 113, respectively. The communication paths 114 and 115 communicate with the merge path 65 and the discharge path 62, respectively. The merging valve 20 is switched to the first switching position 20b when the pilot pressure oil acts on the pilot pressure receiving unit 100. Although the first oil passages 104 and 80 are communicated with the first pilot oil passage 76 that communicates the pilot port Pp1 and the pilot pressure receiving part 100, the first oil passages 104 and 80 communicate with each other through the restrictors 105 and 78, respectively. The pressure of the pilot pressure receiving unit 100 is switched from the unload position 20a to the first switching position 20b without decreasing.

With the above connection configuration, the first switch position 20b can supply more pressure oil from the third pump 5 to the second circuit b than the first circuit a. Further, since unnecessary pressure oil is discharged to the tank through the throttle 115, the third pump does not become overloaded.

Next, in the second switching position 20c, one of the supply passages 61a is communicated with the first joining passage 65 via the communication passage 117 provided with the throttle 116, and the other supply passage 61 is connected.
It keeps blocking about b. Then, the downstream side of the third unload passage 42 is communicated with the communication passage 117 to communicate with the first merge passage 65, and the second merge passage 66, via the communication passages 119, 121 provided with the throttles 118, 120, respectively. The exhaust oil passage 62 is also communicated. The opening of the diaphragm 120 is smaller than that of the diaphragm 113.

A pilot port Pa5 is provided between the first switching position 20b and the second switching position 20c.
, The pressure is switched proportionally / stepwise depending on the pressure balance of Pa8. That is, when the pressure of the pilot port Pa8 increases, the merging valve 20 moves to the second switching position 20c,
Increase the amount of oil sent to the first circuit a. On the other hand, when the pressure of the pilot port Pa5 increases, the merging valve 20 moves to the first switching position 20b and increases the amount of oil sent to the second circuit a. The pressure introduced into the merging valve 20 is the pilot ports Pa5 and Pa8, but the load pressure of the boom cylinder 30 and the load pressure of the arm cylinder 26 may be used.

The second switching position 20c also serves as a running position. That is, the first circuit a and the second circuit b are equally distributed to the running position 20d of the hydraulic circuit 1 by the throttle 118.
In this case, the running position 20d is omitted and simplified. Second position 20c
Switching to both the right traveling direction switching valve 17 and the left traveling direction switching valve 16,
The pilot pressure oil sent from the pilot pump 6 acts on the pilot pressure receiving part 102 when at least one of the other direction switching valves (18, 19) other than the right traveling direction switching valve 17 in the circuit a is operated. It is done by doing.

The pressure oil sent from the pilot pump 6 through the first pilot oil passage 76 is also partially sent to the first oil passage 104 through the throttle 105. The first oil passage 104 communicates with a travel signal oil passage 106 and also communicates with a second pilot oil passage 108 connected to the pilot pressure receiving part 102 via a throttle 107.

The travel signal oil passage 106 is connected to a switching valve communication oil passage 106a that communicates with the tank passage 35 by connecting the sub valves 16s and 17s of the left and right travel direction switching valves (16, 17), and the travel signal extraction port PL. It branches off to the travel signal extraction oil passage 106b.

Further, a second oil passage 109 branches from the second pilot oil passage 108 on the downstream side of the throttle 107, and this second oil passage 109 is a sub valve 18s of the boom direction switching valve 18 in the first circuit a. And the sub valve 19s of the bucket direction switching valve are connected to the tank passage 35.

Due to the configuration of these oil passages (104, 105, 106, 107, 108, 109), when none of the left and right traveling direction switching valves (16, 17) is operated, the operation proceeds to the first oil passage 104. The pressure oil that has flowed in reaches the tank passage 35 from the switching valve communication oil passage 106a. When at least one of the left and right traveling direction switching valves is operated, the switching valve communication oil passage 106a is shut off, and a traveling signal is generated from the traveling signal extraction oil passage 106b. From this state, when either the boom direction switching valve 18 or the bucket direction switching valve 19 is operated, the second oil passage 109 is shut off, and pressure oil flows into the second pilot oil passage 108, Pressure oil acts on the pilot pressure receiving portion 102, and the merging valve 20 is switched to the traveling position (second switching position) 20c.

Thus, even when the traveling direction switching valve (16, 17) and the other direction switching valve (18, 19) other than the traveling direction switching valve are operated at the same time, the other direction switching valve is surely provided. The pressure oil pumped from the third pump 5 can be supplied to (18, 19).

In the hydraulic circuit 2, the configuration of the pilot passage for switching to the traveling signal and the traveling position (second switching position) 20c is different. The first oil passage 104 communicating with the pilot pump 6 branches to a traveling signal oil passage 106 and a second pilot oil passage 108, and a traveling signal is taken out from the signal for the traveling position (second switching position) 20c to be safe. Used for the device. Thereby, it is not necessary to provide a pilot passage or a sub valve for the safety device, and the directional switching valves 16 and 17 can be prevented from being enlarged. Furthermore, since the travel signal oil passage 106 serves both as a travel signal and a signal for switching to the travel position (second switching position) 20C, the sub valves 16 and 17 of the travel direction switching valve can be simplified.

It is a circuit diagram of the hydraulic circuit which concerns on a present Example. It is an enlarged circuit diagram of the junction valve in the hydraulic circuit which concerns on a present Example. It is a circuit diagram of the hydraulic circuit which concerns on a modification. It is an expanded circuit diagram of the confluence | merging valve in the hydraulic circuit which concerns on a modification. It is the schematic which shows the construction machine which can apply the hydraulic circuit which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Hydraulic circuit 3 1st pump 4 2nd pump 5 3rd pump 6 Pilot pump 11-19 Directional switching valve 20 Merge valve 20a Unloading position 20b 1st switching position 20b 2nd switching position 22 Dozer 25 Arm 27 Left travel Device 28 Right traveling device 29 Boom 31 Bucket 33 Swivel table 36 Tank 65 First joining passage 66 Second joining passage 72, 73, 74 Pilot pressure receiving portion 97 Auto idle oil passage 99 Driving signal oil passage 150 Mini excavator a first 1 circuit b 2nd circuit c 3rd circuit

Claims (2)

Used in construction machines with safety devices that inform the surroundings that it is running, and an auto idle function that controls the rotational speed of the drive source according to the operating state of each actuator,
It controls the connection direction and the hydraulic fluid of the flow rate of the hydraulic pump or tank and the traveling device, hydraulic motor for driving the left traveling device and the hydraulic motor for driving the right-side running line device, the left and right traveling A direction switching valve;
Another direction switching valve for controlling the connection direction of the pump or tank and other actuators other than the traveling device and the flow rate of pressure oil ;
A travel signal oil passage for operating the safety device that emits a travel signal by operating the travel direction switching valve;
An auto-idle oil passage that emits an auto-idle signal by operating the other direction switching valve,
Pilot pressure oil is supplied to the auto idle oil passage and the travel signal oil passage through a pilot port,
The travel signal oil path includes a switching valve communication oil path, and a travel signal extraction oil path that branches from the switching valve communication oil path,
The switching valve communication oil passage is connected to the tank passage after being connected to each sub-valve of the left and right traveling direction switching valves,
The travel signal extraction oil passage communicates with a travel signal extraction port,
When at least one of the left and right traveling direction switching valves is operated, pressure is generated in the traveling signal extraction oil passage, a traveling signal is generated in the traveling signal extraction port,
When neither the travel signal nor the auto idle signal is generated, the rotational speed of the drive source is reduced to a predetermined value, and when either the travel signal or the auto idle signal is generated, A hydraulic circuit characterized by performing control to increase the rotational speed to a predetermined value.   The hydraulic circuit according to claim 1,
  A first oil passage communicating with the first pilot oil passage communicating with the pilot port and the pilot pressure receiving portion;
  The first oil passage communicates with the travel signal oil passage, and communicates with the second pilot oil passage through a throttle.
  A second oil passage is branched from the second pilot oil passage on the downstream side of the throttle. The second oil passage is connected to a sub valve of the boom direction switching valve and a sub valve of the bucket direction switching valve. And communicating with the tank passage,
  At least one of the left and right traveling direction switching valves is operated, and from this state, when either the boom direction switching valve or the bucket direction switching valve is operated, the second oil passage is shut off, A hydraulic circuit, wherein pressure oil flows into a second pilot oil passage.

Images