JPS5891906A - Oil hydraulic circut of oil hydraulic working machine - Google Patents

Abstract

PURPOSE:To independently perform running action in the captioned circuit equipped with two hydraulic pumps, by forming a direction selector valve group for one pump and another direction selector valve group for another hydraulic pump, and connecting the mutually opposite direction running selector valve of each group to a center bypass in the upstream side of the direction selector valve of an actuator. CONSTITUTION:Under a condition as shown in the drawing, pressurized oil of the first oil hydraulic pump 41 fed to a pump circuit 64 conducts a selector valve 71, and pressurized oil of the second oil hydraulic pump 42 is supplied to a right running selector valve 52 and left running selector valve 45 to drive both left and right running motors 57, 62 and keep a straight forwarding characteristic. Pressurized oil of the first pump 41 is supplied to either one among the arm direction selector valve 46, boom direction selector valve 47, bucket direction selector valve 48 or turning direction selector valve 49 to perfectly perform independent operation of the running and the other driving of an actuator.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic circuit for a hydraulic working machine such as a hydraulic excavator that is equipped with a plurality of actuators.

In general, a hydraulic excavator is equipped with a revolving body, a running body, and attachments such as a poom, an arm, and a packet. Driven. These actuators can be operated individually or in an expanded combination by their respective directional control valves, but in conventional hydraulic drive systems, these directional control valves are divided into two groups. Each group is connected to a separate hydraulic pump, and within each group the directional valves are connected in parallel to the hydraulic pumps.

This method has a simple hydraulic circuit and has the advantage of being able to drive each actuator simultaneously to some extent, but on the other hand, when multiple actuators are operated in a complex manner, the movement of each actuator is affected by the working pressure of each other, so control is difficult. If this cannot be done accurately, and if there is an extreme difference between the operating pressures of multiple actuators that operate in combination depending on the load condition on the actuators, pressure oil may be applied to only the actuator with the lower operating pressure. As a result, the operation of the other actuator may stop.

As an example of a solution to this problem, a hydraulic circuit shown in FIG. 1 has been proposed. This hydraulic circuit basically consists of a hydraulic pump and a number of directional control valves connected in tandem. In FIG. 1, two hydraulic pumps 1.2 are provided, and for the hydraulic pump 1, a swing motor 3, a left travel motor 4 and an arm cylinder 5 form one group, a right travel motor 6, a packet cylinder 7
and boom cylinder 8 form another group.

Directional control valves 9.10.11 are then connected in tandem to the hydraulic pump 1, and directional control valves 12.15.14
are connected to the hydraulic bonder 2 in tandem. Directional switching valves 9 to 11 form a first directional switching valve group 15, and directional switching valves 12 to 14Fi form a second directional switching valve group 16.

17.18 is an on-off valve, 19-24 is a pilot valve, 25
is a pilot pump, 26 to 29 are bypass lines, 5
0 is a restriction valve, 31 is a throttle, 52 is a selection valve, 33 is a switching valve, and 厘~l is a violet pressure signal circuit.

In the hydraulic enclosure of FIG. 1, the swing motion is completely independent of the travel, boom, and packet motions. In addition, for arm operation, since the throttle 31 is inserted into the bypass fin 29, even when the operating pressure of the arm cylinder 5 is low, the pressure generated in the throttle 31 is applied to the swing motor 5 at a minimum. , the turning motion ensures a certain degree of independence.

However, the drawback of the traveling operation is that it is not independent from other actuator operations other than the turning operation.

It is an object of the present invention to eliminate the above-mentioned drawbacks, to allow the travel operation to be performed independently of other actuator operations, and to eliminate excess pressure oil when the travel directional control valve is in the half-open state. It is an object of the present invention to provide a hydraulic circuit for a hydraulic working machine which can effectively utilize the hydraulic power for other actuators and can increase the speed of travel when desired.

In order to achieve this objective, the present invention has been expanded to provide a first directional control valve group in which one of the left and right directional control valves is used as a directional control valve for an actuator that is subject to a combined operation with driving. The second directional valve group is connected to the center bypass on the upstream side of the valve, and in the second directional valve group, the other of the left and right travel directional valves is used as the directional switch for the actuator that is subject to combined operation with travel. Connected to the center bypass on the upstream side of the valve, the pressure oil of the first hydraulic pump is normally supplied to the directional control valve for the actuator, which is subject to combined operation with the travel at the directional control valve @1, increasing travel. The present invention is characterized in that a switching valve is provided to supply the one running directional switching valve at high speed, and a pump boat is connected to the one running directional switching valve and the other running directional switching valve.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

FIG. 2 shows an embodiment of the invention. First and second directional valve groups 45.44 are provided for the first and second hydraulic pumps 41.42.

In the first directional switching valve group 4S, a left running directional switching valve 45, a first arm directional switching valve 46, a second boom directional switching valve 47, a second packet directional switching valve 48,
Center bypass ports are connected in series in the order of the turning directional control valve 49 to form a center bypass 50, and the terminal end of the center bypass 50 is connected to a tank 51. In the second directional valve group 44, the right travel directional valve 52, the first boom directional valve 55, the 10-packet directional valve 54, and the second arm directional valve 55 are connected to the center bypass in this order. The ports are connected in series to form a center bypass 56. Directional switching valve 45-49.52
55 are connected to a left travel motor 57, an arm cylinder 58, a boom cylinder 59, a packet cylinder 60, a swing motor 61, and a right travel motor 62, respectively.

A manual switching valve 65 connects the discharge side of the first hydraulic pump 41 to the first pump circuit 64 during normal operation and to the second pump circuit during operation.
pump circuit 65. The first pump circuit 64 passes through the check valves 66 and 67 and the throttle valve 8 for 1 s.
It is connected to the pump boat and center bypass port of the first arm directional switching valve 46, and the second 1-arm directional switching valve 47, the second packet directional switching valve 48, and the swing directional switching valve 49. Connected to pump port.

The second pump circuit 65 is connected to the pump boat of the left travel directional control valve 45 and the center bypass port.

A pump circuit 69 connected to the discharge side of the second hydraulic pump 42 is connected to the right travel directional control valve 56C) pump boat and center bypass port. In the directional control valve group 44 of -jI2, the butterfly/boom directional control valve 53 and the packet directional control valve 54 are connected in parallel, and the upper R
It is connected in tandem to the right direction switching valve 52. The arm directional switching valve 55 is connected in tandem to the other directional switching valves 52 to 54 at the most downstream position.

The pump ports of the left running directional switching valve 45 and the right running directional switching valve 520 are connected by a bypass circuit 7o, and a mine switching valve 71 is inserted into the bypass circuit 70. Switching valve 71
The pressure in the pump circuit 64 is sN' and the pressure in the pilot pressure circuit 7 is sN'.
It is switched by being guided by 2. That is,
When pressure is generated in the pump circuit 64, it is in the open position, and when no pressure is generated, it is in the closed position.

73 is a check valve, and 74 is a relief valve.

Two arm directional valves 46.55, two poom directional valves 47.55, two packet directional valves 4
8.54 are configured to operate in conjunction with each other by operating the same operating lever O.

Next, the operation will be explained.

(1) When the switching valve 65 is switched to the state shown in Fig. 2, that is, the connection position to the first pump circuit 64 (1) During combined operation of traveling and other actuators, the first hydraulic pressure is applied to the pump circuit 64. Since the pressure oil from the pump 41 is being sent, the pressure causes the switching valve 71 to be in the open position. by this,
The 20th hydraulic pump 42O pressure oil is the right travel direction switching valve 52
It is also supplied to the left travel direction switching valve 45, and both left and right travel motors 57, 62 are driven to maintain straight travel. The pressure oil of the $111 hydraulic pump 41 is supplied to any one of the arm directional switching valve 46, the boom directional switching valve 47, the packet directional switching valve 48, and the swing directional switching valve 49. Therefore, travel, arm, boom, packet, and rotation operations are completely independent.

Both the left and right travel directional control valves 45.52Fi are located at the most upstream side of the center bypass 5o156 of the directional control valve crew 7"45.44, so for example, when the travel and arm operations are combined, the left and right travel direction changeover valves 45.52 is in the middle of switching position, that is, in a half-open state, a part of the pressure oil of the hydraulic pump 42C1 flows into the arm directional switching valve 46.55, and the pressure oil of the hydraulic pump 41 flows into the arm cylinder 58. The pressure oil of the hydraulic pump 42 is combined and supplied.
The operating speed of the arm increases and excess pressure oil is used effectively.

(2) During combined operation of swing and boom! Pressure oil from the hydraulic pump 41 of g1 is supplied to the second boom directional control valve 47 and the swing direction control valve 49, and
The pressure oil of the hydraulic pump 42 is supplied to the first pool directional control valve 53.
supplied to During swing acceleration, the operating pressure of the swing motor 61 tends to increase due to the large inertia of the swing body, but since the boom direction switching valve 47 of II2 and the swing direction switching valve 49 are connected in parallel, Boom cylinder 5
It is suppressed by the working pressure of 9, and there is no relief.

The remaining pressurized oil is supplied to the poom cylinder 59 at the swivel curvature 61, and the pressurized oil is effectively used for the poom operation, so that the poom can be raised sufficiently.

The control lever for the boom is operated in two steps, and the operation of the first step operates only the first poom directional switching valve 53, and the operation of the second step operates the first and second boom direction switching valves. Valve 5
If 3.47 is configured to work, the turning and zooming will be completely independent in the 1st R, resulting in 9 movements, and in the 2nd R
This is an operation in which the pressure oil of the hydraulic pump 41 is divided into the swing motor 61 and the poom cylinder 59.

(3) During combined operation of swing and arm, the pressure oil of the first hydraulic pump 41 is supplied to the first arm directional switching valve 46 and the swing directional switching valve 49, and the pressure oil of the second hydraulic pump 42 is supplied to the second arm directional switching valve 55. During acceleration of the swing, the operating pressure of the swing motor 61 is suppressed to a value obtained by adding the pressure of the throttle 68 to the operating pressure of the arm cylinder 58, and there is no relief. Even if the operating pressure of the arm cylinder 58 becomes low, the presence of the throttle 68 generates the pressure necessary for accelerating the swing motor 61 in the sand pump circuit 64, so the swing motor 61 can be accelerated, and the swing and arm The operation is almost independent.

(4) At the time of combined operation of turning and packet As in the case of combined operation of turning and packet, there is no relief during turning acceleration, and the operation of the first stage of the packet control lever completely separates the turning and packet. There are nine independent operations, and the second stage operation is an operation for dividing the pressure oil of the hydraulic pump 41 into the swing motor 61 and the packet cylinder 60.

(5) 1st during combined operation of poom, arm, and packet
Directional switching valve 4 for the first arm of the hydraulic pump 41
6. The pressure oil of the second hydraulic pump 42 is supplied to the 20th zoom direction switching valve 47 and the second packet direction switching valve 48, and the pressure oil of the second hydraulic pump 42 is supplied to the first boom direction switching valve 55 and the @1 packet direction switching valve. It is supplied to the switching valve 54. As a result, three 7 cutuators 58, 59, 60 are driven simultaneously.

In any of the directional control valves, operation of the first stage of the operating lever operates the first directional control valve 46, 53, 54, and the second directional control valve operates.
The first and second directional control valves 46.55.5 are operated by the R eye.
4.55.47.48 is configured to work, 1
In stage operation, the poom, packet, and arm are completely independent and have nine movements.

At this time, the packet is always moved under load, so the operating pressure of the packet cylinder 60 is considerably high, and therefore the operating pressure of the boom cylinder 59 is also considerably high, making it possible to raise the boom without fail.

(6) At the time of combined operation of swing, poop, and packet, the swing motor 61 is operated by pressure oil from the first hydraulic pump 41, and the poop cylinder 59 and packet cylinder 60 are operated by the first and second hydraulic pumps.
are simultaneously driven by pressure oil from hydraulic pumps 41 and 42. By operating the 01st stage of the operating lever, the poom, packet, and turning operations become completely independent. At this time, the zoom can be raised without fail, as is the case with the combined operation of the poom, arm, and packet.

(7) During combined operation of the boom and the arm, the working pressure of the boom cylinder 59 is generally higher than the working pressure of the arm cylinder 58, so the pressure oil of the first hydraulic pump 41 flows through the first arm directional control valve 46. It is then supplied to the arm cylinder 58, and then to the boom cylinder 59 via the first boom directional switching valve 53 of the second hydraulic pump 42, thereby maintaining its independence. If you operate the first stage of the operating lever, the operation will be completely independent of the foot and arm.

■, When the switching valve 63 is switched to the connection position to the pump circuit 65 of wE2, when you want to travel quickly over a long distance, the oil pressure is 7! The switching valve 65 is switched to the connection position to the second pump circuit 65 when, for example, when loading a bell onto a trailer, it is desired to operate the left and right travel independently in order to turn the steering reliably. As a result, the pressure in the first pump circuit 64 disappears, and the switching valve 71 is switched to the closed position. When the operating lever for left and right travel is operated, the pressure oil of the hydraulic pump 41 of @1 is transferred to the left travel motor 57 by the left travel direction switching valve 45.
Pressure oil from the second hydraulic pump 42 is supplied to the right travel motor 62 by the right travel direction switching valve 52, and the left and right travel speed increases, and left and right travel becomes completely independent operations. If the left running directional control valve 45 is set to the mid-switching position (half-open state), excess pressure oil flows to the center bypass 50 downstream thereof, so the arm directional control valve is operated by operating the arm control lever. 46 and flows into the arm cylinder 58, allowing effective use of the pressure oil.

Similarly, if the right travel directional control valve 52 is set to the mid-switching position (half-open state), excess pressure oil can be removed from the directional control valve 55 for the pool or the packet direction by operating the control lever for the pool or the packet. It flows into the boom cylinder 59 or packet cylinder 60 via the switching valve 54.

According to this embodiment, the following advantages can be obtained.

(1) Traveling can be made independent of turning, punim, arm, and packet movements.

(b) When the traveling directional control valve is set in a half-open state, the remaining 1 liter IO pressure oil can be effectively used for 0 operation of the boom, arm, and bucket.

(C) Traveling speed can be increased and left and right independent as needed.

(d) It is possible to ensure independence of turning and traveling, boom, arm, and gap F.

(e) Relief loss during turning acceleration can be eliminated during combined operation of turning and other actuators.

(f) Boom, arm, bucket) Q The boom can always be raised during combined operations and during combined operations of turning, boom, and packet.

(-Since at least two hydraulic pumps can be used, the hydraulic circuit becomes simple and manufacturing costs are reduced.

In the embodiment shown in FIG. 2, the switching valve 71 may not be provided and the bypass circuit w170 may be opened at all times. In this case, even if the switching valve 65 is switched, left and right travel will not be possible.
It is not an independent operation. The second packet directional switching valve 48 may not be provided. In this case, this directional control valve glue can be used as an attachment F for breakers, rotary drum shells, and the like. The aperture 68 is not necessarily required. If the aperture 68 is not provided, there will be no independence between the swing and the arm.

The switching valve 63 is not limited to a manual type; for example, it may be configured to be automatically switched during single-travel operation.

As explained above, according to the present invention, the first
Since the pressure oil from the second hydraulic pump is supplied to the directional control valve for the actuator that is subject to combined operation with driving, and the pressure oil from the second hydraulic pump is supplied to the directional control valve for left and right travel, it is possible to This can be done by making the operation take place independently of other actuator operations. In addition, both of the left and right travel directional control valves are connected to the center bypass l on the upstream side of the actuator directional control valve that is subject to combined operation with travel, so when the travel directional control valve is in the half-open state, Surplus pressure oil can be effectively used for other actuators. Furthermore, when speeding up the vehicle, the switching valves are switched to supply pressure oil from the first and second hydraulic pumps to the left/right travel direction switching valves, thereby increasing the traveling speed.

[Brief explanation of the drawing]

Figure 1 is a hydraulic circuit diagram of a conventional hydraulic seal, and Figure 2 is a hydraulic circuit diagram of an embodiment of the present invention. 41... Hydraulic pump of 11c1, 42... Second hydraulic pump, 43... Directional switching valve glue A of jgl, 4
4... 20 direction switching valve group, 45... Directional switching valve for left running, 46... Directional switching valve for 10th arm,
47...Second boom directional control valve, 48...Second
Directional switching valve for packet, 49... Directional switching valve for turning, 50... Center bypass, 52... Directional switching valve for right travel, 55... Directional switching valve for #11 boom, 54
... JIll packet directional switching valve, 55... Second arm directional switching valve, 56... Center bypass,
57...Left running peak, 58...Arm cylinder,
59...Boom cylinder, 60...Packet cylinder, 61...Swivel motor, 62...Right travel motor,
63...Switching valve, 70...Bypass circuit.

Claims (1)

[Claims] 1, a plurality of hydraulic pumps, a plurality of actuators driven by pressure oil from the hydraulic pumps, and a plurality of directional switching valves that control the direction and flow rate of the pressure oil supplied from the hydraulic pumps to the actuators; A hydraulic circuit for a hydraulic working machine in which a first directional valve group is formed for 10 hydraulic pumps and a second directional valve group is formed for 1s2 hydraulic pumps. In the valve group, one of the left and right travel directional control valves is connected to the center bypass upstream of the actuator directional control valve that is subject to combined operation with travel, and the second directional control valve In the group, the other of the left and right travel directional control valves is placed above the actuator directional control valve that is subject to combined operation with travel.
14 center bypass, and normally supplies pressure oil from the first hydraulic pump to the directional control valve for the actuator that is subject to combined operation with travel in the first directional valve group, and when increasing travel speed. A hydraulic working machine, characterized in that a switching valve is provided to supply the one running directional switching valve, and a pump boat is connected to the one running directional switching valve and the other running directional switching valve. Hydraulic circuit.