JPS5865828A - Oil-pressure circuit for civil work and construction machinery - Google Patents

Abstract

PURPOSE:To allow the straight running of a civil work and construction machine using plural oil-pressure pumps as driving sources by using a contrived circuit constitution to uniformly supply pressure oil left and right-handed running motors when operating various actuators during the running period. CONSTITUTION:For an oil-pressure shovel, direction switching valves 21, 28, and 23 to operate a bucket cylinder 13, a boom cylinder 11, and a right-side running motor 7 are connected in parallel to the first oil-pressure pump 20. Also, direction switching valves 26, 29 and 25 to operate a turning motor 3, the boom cylinder 11, and an arm cylinder 12 are connected in parallel to the second oil-pressure pump 24, and a direction switching valve 27 to for a left-side running motor 5 is connected in tandem to the downstream side of the arm direction switching valve 25. The input portion of the direction switching valve 27 and the discharge oil supply circuit of an oil-pressure port are connected with a circuit 33 having a load check 31c and throttle 34 on its midway.

Description

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

In general, civil engineering and construction machines, such as hydraulic excavators, are equipped with a rotating body and attachments on the traveling body, such as a boom, an arm, and a packet, each of which has a rotating motor,
Difference: right-hand travel motor, boom cylinder, arm syringe,
Driven by an actuator, such as a packet cylinder. These actuators are each controlled by a directional control valve. FIG. 1 is a side view showing the overall configuration of the hydraulic excavator, and FIG. 27 is a plan view of FIG. 1.

In these figures, reference numeral 1 denotes an enclosure, which is disposed at the L portion of the running body 2 and rotates by driving a rotation motor 3. 4 is a left truck, which is driven by a left traveling motor 5. 6 is a right-hand truck, o8 is a boom driven by a right travel motor 7, 9 is an arm, 10 is a packet,
These things cause the work equipment to twitch. 1. ,
Boom cylinder that operates IH boom 8, '12 (
, an arm cylinder that operates the i-arm 9, and 13 a packet cylinder that operates the packet 10.

Figure 73 shows the conventional hydraulic pressure installed in the above-mentioned hydraulic excavator [[! FIG. 2 is a circuit diagram showing an example of a l-path. In one of these units 1, 20 is a hydraulic pump 8'01, and 21 is a packet force direction switching valve, which is interposed between the first hydraulic pump 20 and the packet cylinder 13. 2.2 is a boom directional switching valve, which is interposed between the packet directional switching valve 21 and the boom cylinder 11. 23 is the right travel direction switching valve, and the boom direction switch J
It is interposed between the pilot valve 22 and the right travel motor 7.

Note that the packet force direction switching valve 21. B~'A Change direction. □, Breathe. The right side 1'6JvJ exchange valve 23 is connected in parallel to the first hydraulic pump 20. In addition to the above, the first hydraulic pump 2, directional control valves 21 and 22
, 23, and the packet cylinder 13. Boom cylinder 1
1. The right travel motor 7 constitutes one independent hydraulic system. Further, 24 is a second hydraulic pump, 25 is an arm directional control valve, and 1. This is interposed between the second hydraulic pump 24 and the arm cylinder 12. Reference numeral 26 denotes a turning directional switching valve, which is interposed between the arm directional switching valve 25 and the swinging mold 3. Reference numeral 27 denotes a left travel direction switching valve, which is interposed between the turning direction change valve 2'6 and the left travel motor 5. Note that the arm directional switching valve 25. Directional switching valve for rotation 1 26. The left running collar switching valve 27 is connected in parallel to the second hydraulic pump 24. The second hydraulic pump 24 described above. directional valve 25.26.27,
and arm cylinder 12. Swing motor 3. The left travel motor 5 constitutes another independent hydraulic circuit.

However, the conventional hydraulic circuit configured as described above has the following problems. In other words, (1) When operating the arm while driving 1. Since the arm direction switching valve 25 and the left running direction switching valve 27 are connected in parallel, the arm direction switching valve 25 and the left running direction switching valve 27 side are connected in parallel. Pressure oil tends to flow toward the arm directional control valve 25, which has a lighter load, and as a result, the operation of the left truck is more likely to occur than the operation of the right truck, making it impossible for a heavy object to travel straight.

In addition, in the past, a combined arm movement operation was performed when escaping from a wetland, etc., but if the left and right trucks were to spin, the arm would not be able to obtain sufficient force. Since the direction changeover valve 26 for left travel and the direction changeover valve 27 for travel are connected separately, the direction changeover valve 26 for turning is smaller than the direction changeover valve 27 for left travel.
Pressure oil tends to flow due to the force, and as a result, the operation of the left truck becomes slower than the operation of the right truck, making it impossible for the vehicle to travel straight. Also, the running load is light.

In some cases, the pressure for turning is insufficient, making it difficult to perform turning operations.

■ When operating the packet while driving, since the packet force direction switching valve 21 and the right running directional switching valve 23 are connected in parallel, the packet has a lighter load compared to the right running directional switching valve 23 side. Pressure oil tends to flow through the power direction switching valve 21, and as a result, the operation of the right truck becomes slower than that of the left truck, making it impossible for the vehicle to travel straight.

■ When operating the boom while traveling, what are the boom directional switching valve 22 and the right travel directional switching valve 23? Due to the parallel connection, sufficient pressure oil is not supplied to the boom side cutoff valve 22 to raise the boom, resulting in a situation where the boom cannot be raised.

The present invention has been made in view of the actual situation in the prior art, and its purpose is to obtain uniform running force on the left and right tracks that make up the running body when operating the various seven cutter units during running. Our goal is to provide hydraulic circuits for civil engineering and construction machinery that can perform

In order to achieve this purpose, the present Komei is equipped with a first boom directional control valve among a plurality of hydraulic pumps that supply pressure oil to the actuator, and a boom directional control valve for one of the left and right traveling The directional switching valves are connected in parallel, and the swing directional switching valve, the arm directional switching valve, and the second boom directional switching valve are connected in parallel to the second Ω hydraulic pump, and the other traveling directional switching valve is connected downstream of the swing directional switching valve, the arm directional switching valve, and the second boom directional switching valve. The directional control valves are connected in tandem, and the input boat of the externally powered directional control valve and the discharge oil supply path of the second hydraulic pump located upstream i' are connected via a pressure regulating means, and - The input port of the power running directional control valve and the input port of the other running directional control valve are connected through a connecting pipe.

Hereinafter, a hydraulic circuit for a civil engineering/construction machine according to the present invention will be explained based on the drawings. FIG. 4 is a circuit diagram showing the configuration of the first embodiment of the present invention, and FIG. 5 is a circuit diagram showing the configuration of the first embodiment of the present invention, and FIG. 5 is a circuit diagram showing the structure of the first embodiment of the present invention. It is indicated by a symbol.

In the first embodiment shown in FIG. 4, a packet directional switching valve 21 that operates the packet cylinder 13, a first boom directional switching valve 28 that operates the boom cylinder 11, and a right travel motor 7. A right travel direction switching valve 23 that operates the right travel direction is connected in parallel to the first hydraulic pump 20. In addition, the swing direction switching valve 26 that operates the swing motor 3, the boom direction switching valve 29 of the vessel 2 that operates the boom cylinder 11, and the arm direction switching valve 25 that operates the arm cylinder 12 are connected to a second hydraulic pump 2
4 in parallel, and the left travel motor 5
A directional switching valve 27 for left running is connected in tandem downstream of the directional switching valve 25 for the arm. Then, the input port of the left travel direction switching valve 27 and the discharge oil supply circuit of the second hydraulic pump 24 located upstream are checked during a load check 31. c and pressure regulating means, e.g. throttle 34.
It is connected by a circuit 33 which is an intervening circuit. Further, the input port of the right-hand travel direction switching valve 23 and the input port of the left-hand travel direction change-over valve 27 are connected through a connecting pipe 3o. Note that the load check 31C and the load checks 31α and 31b described above are provided to prevent backflow of discharged oil.

The operation of the hydraulic circuit configured as described above is as follows.

When operating the traveling direction switching valve 23, 27 independently,
Same as normal operation. That is, the oil discharged from the first hydraulic pump 2o is checked by the load check 31α from the parallel circuit.
The oil discharged from the second hydraulic pump 2.4 is supplied from the center bypass circuit to the left travel direction changeover valve 27 through the load check 31b.

If you operate the self-explanatory switching valve 25 with the arm protruding while driving by operating the running directional switching valve 23 * 27, the pressure oil of the first hydraulic pump 20 will be transferred to the right running directional switching valve. It is sent to the right travel motor 7 through 23 and moves it.On the other hand,
Pressure oil from the second hydraulic pump 24 is supplied to the arm cylinder 12 via the arm directional switching valve 25. At the same time, a portion of the pressure oil from the second hydraulic pump 24 is also supplied to the left travel direction switching valve 27 through the circuit 33. As mentioned above, part of the pressure oil from the second hydraulic pump 24 flows to the arm cylinder 12 and the rest flows to the left travel direction changeover valve 27. Although the amount is insufficient, the pressure oil of the first hydraulic pump 2o is also supplied to the left travel direction switching valve 27 through the connecting pipe 30, so the left travel motor 5 is driven in the same way as the right travel motor 7. . Here, the oil supply circuits for the left travel motor 5 and the right travel motor 7 are connected in parallel by a connecting pipe 3o, and it seems that the amount of oil does not necessarily flow equally. - It is possible to maintain straight running due to the inherent straightness of the vehicle itself. In this way, the discharge oil from the second hydraulic pump 24 can be supplied to the arm cylinder 12 with priority, and the left travel motor 5 can be supplied with priority.
Also, since the right travel motor 7 can be supplied with the oil discharged from the first hydraulic pump 2o and the remaining oil discharged from the second hydraulic pump 24, the straightness is not impaired, and a! Sufficient force can be secured in the arm even when escaping from a wetland using a combination of arm and travel operation.

In addition, when operating the turning direction switching valve 26 while operating the running direction switching valve 23, 27, the discharge oil of the hydraulic pump 24 of the beam 2 is k(gI force direction switching valve 26
Although there is a shortage of oil to the left travel motor 5, the first hydraulic pump 2 is
Since zero discharged oil is supplied to the left travel motor 5 and the right travel motor 7, straight traveling performance can be maintained.

In addition, when operating the packet direction changeover valve 21 while driving by operating the travel direction changeover valve 23127, the first
Pressure oil from the hydraulic pump 20 is supplied to the packet cylinder 1 via the packet directional switching valve 21 and the right travel directional switching valve 23.
3 and the right travel motor 7. Therefore, the pressure oil supplied to the right travel motor 7 decreases, but since it is connected and supplied from the second hydraulic pump 24 that supplies pressure oil to the left travel motor 5, straightness is maintained. be able to.

Also, when operating the boom directional control valve 28, 29 while traveling with the travel directional control valve 23, 27 operating, the pressure oil from the hydraulic pump 24 of II2 is restricted by the restriction 34. Therefore, the flow to the left travel direction switching valve 27 is <<,
This pressure oil is mainly supplied to the boom cylinder 11 via the second boom directional switching valve 29, and the pressure oil from the Ml hydraulic pump 2o passes through the running directional switching valve 23, 27 to the right travel motor 7 and the left Since it is supplied to the traveling motor 5, the boom can be reliably raised even when the traveling pressure is low.

The example of @2 shown in $15@l is #1I4W! The configuration is basically the same as that of the first embodiment shown in 4, but the interesting point is that the input boat of the right-hand travel direction switching valve 23 and the input boat of the left-hand travel direction change-over valve 270 are connected. This is because an on-off valve 32 is provided in the middle of the connecting pipe 30. This on-off valve 32 may be operated manually by the operator's hands, or may be operated by pedal operation using the foot. In the second embodiment configured as shown in -, opening/closing/j-32 is operated as appropriate. This makes it possible to operate the left travel motor 5 and the right travel motor 7 individually, which makes it possible to maintain straight travel, especially on slopes, when only the travel operation is performed independently.

In the #ill second embodiment described above, the packet directional switching valve 21, the first boom directional switching valve 28, and the right travel directional switching valve 23 are connected to the first hydraulic pump. However, it is also possible to connect only the outer valve 21 in tandem instead of connecting the outer valve 21 in parallel. Even in this way, the same effect as above can be obtained.

Further, in the above description, the throttle 34 is mentioned as the pressure regulating means provided in the circuit 33, but a 5N6 type may be provided in which a relief valve is provided in place of the throttle 34.

As described above, in the hydraulic circuit for civil engineering and construction machinery of the present invention, the first hydraulic pump is connected in parallel with the first arm directional switching valve and one traveling directional switching valve, and the second hydraulic pump includes a directional switching valve for swinging, a directional switching valve for arm, and a second directional switching valve.
The two arm directional switching valves are connected in parallel, and the other-powered running directional switching valve is connected in tandem downstream thereof, and is located upstream of the input port of the other running directional switching valve.

The discharge oil supply circuit of the second hydraulic pump is connected via a pressure regulating means, and the input boat of one running directional switching valve and the input boat of the other running directional switching valve are connected by a connecting pipe. ＆ Because it is a suction pump, when operating the actuators of each building while driving, pressure oil from the first hydraulic pump or second hydraulic pump is supplied to the left travel motor and right travel motor via the connecting pipe. It is possible to supply evenly, and it is possible to obtain uniform running force to the left and right tracks that make up the running body. Therefore, various actuators can be operated properly, and it is possible to drive straight ahead. There is.

[BRIEF DESCRIPTION OF THE DRAWINGS] Figure vJ1 is a side view showing the overall configuration of a hydraulic excavator as an example of a civil engineering/construction machine to which the present invention is applied.
The figure is a plano-concave view of the axis 1, Figure 3 is a circuit diagram showing an example of the hydraulic circuit of a conventional civil engineering/construction machine, and Figure 4 is a diagram of the civil engineering/construction machine of the present invention.
Circuit diagram showing the hydraulic circuit of the construction machine and the first embodiment, No. 5
The figure is a circuit diagram-C showing a second embodiment of the hydraulic circuit for civil engineering/construction machinery of the present invention. 1... Rotating body, 2... Traveling body, 3.:
...Swivel motor, 4...Left truck, 5.
...Left drive mode, 6...Right track,
7...Right travel motor, 8...Boom,
9...Arm, 11...Boom cylinder, 12...Arm cylinder, 20...
・First hydraulic pump 1.23... Force direction switching valve for right travel, 24... Second hydraulic pump, 25...
... Directional switching valve for boom, 26... Directional switching valve for turning, 27... Directional switching valve for left travel, 28
...First boom directional control valve, 29...
...Second boom directional control valve, 30...Connection pipe, 31α, 31b, 31C...Load check, 32...Opening/closing valve, 33... ··circuit,
34...Aperture (sweat, force adjustment means). Figure 1 0 Figure 2;

Claims (1)

[Claims] 1. A plurality of hydraulic pumps, a plurality of actuators driven by pressure oil from these hydraulic pumps, and the direction and flow rate of the pressure oil supplied from the hydraulic pumps to the actuators. In a hydraulic circuit for civil engineering and construction machinery that is equipped with a plurality of directional switching valves that control At the same time, connect the directional switching valve for use in parallel, and connect the directional switching valve for swing to the hydraulic pump of storage 2, and the directional switching valve for arm side] 7! The valve and the second boom-oriented directional control valve are connected in parallel, and the two downstream directional control valves for traveling are connected in tandem, and the input boat and upstream of the other directional control valve for traveling are connected in tandem. The second hydraulic pump is located at the second hydraulic pump. and the discharge oil supply circuit of the above-mentioned one through a pressure regulating means, and the human-powered boat of the above-mentioned power running directional control valve and the input boat of the other above-mentioned running directional switching valve are connected through a connecting pipe. Features hydraulic circuits for civil engineering and construction machinery. -2 Patent a characterized in that the pressure adjustment means is a throttle
Hydraulic circuit for civil engineering and construction machinery as described in Section 1 of No. 1. 3. The hydraulic circuit for civil engineering and construction machinery as set forth in claim 1, wherein the pressure regulating means is an IJ IJ-7 valve. 4. Civil engineering/construction e@ described in paragraph 2 or 3 of the patent claim, characterized in that an on-off valve is provided in the middle of the connecting pipe.
machine hydraulic circuit.