JPH0772427B2 - Hydraulic circuit of hydraulic shovel - Google Patents

Description

The present invention relates to a hydraulic circuit of a three-pump hydraulic excavator.

(Prior Art) Conventionally, in a two-pump type hydraulic excavator, for example, in order to prevent the straightness of traveling from being impaired during traveling and turning or a combined work of each attachment (boom, arm, bucket), for example, As shown in Japanese Patent Laid-Open No. 57-197333, the discharge oil of the left and right pumps is once combined by a communication valve, and then supplied to the left and right running motors and other actuators in parallel, that is, the actuators of the turning or each attachment. There is something I did.

However, in this circuit, since pressure oil is individually supplied from the left and right pumps to the left and right traveling motors when the vehicle is independently operated, the flow rate of the pressure oil supplied to the left and right traveling motors can be increased and steering is also possible. However, if other actuators such as turning are operated during traveling to perform combined work of the traveling motor and other actuators, the flow rate supplied to the left and right traveling motors will decrease significantly, and the traveling speed will decrease extremely. There is a risk of shock, and since pressure oil is supplied in parallel to the left and right traveling motors, steering cannot be performed even if the left and right traveling control valves are operated, especially the operating pressure of other actuators. If it is low, there is a problem that the oil will flow to the actuator side and the pressure oil will not be supplied to the left and right traveling motors, so that the vehicle cannot travel.

Further, as another conventional method, as shown in Japanese Utility Model Laid-Open No. 60-80152, the traveling communication valve is switched during traveling and compound work with other actuators so that the oil discharged from one pump is supplied to the left and right traveling motors. In addition to the supply, the discharge oil of the other pump is supplied to another actuator, and the remaining oil is combined with the discharge oil of the one pump to replenish the left and right traveling motors.

According to this circuit, the pressure oil can be supplied to the left and right traveling motors without being influenced by the pressure of the other actuators during the combined operation of traveling and the other actuators. And the remaining oil (a small amount) supplied to other actuators out of the oil discharged from the other pump is only supplied, so similar to the circuit described above, other oil such as turning while traveling can be avoided. When the actuator is operated to perform a combined work of the traveling motor and other actuators, the supply flow rate to the left and right traveling motors is greatly reduced, the traveling speed is extremely reduced, and the left and right traveling motors are There is a problem that steering cannot be performed because pressure oil is supplied in parallel.

(Object of the Invention) The present invention has been made in order to solve such a conventional problem, and even if a turn or each attachment is operated during traveling, the traveling speed does not decrease and traveling To provide a hydraulic circuit for a hydraulic excavator that enables proper running even during turning and complex work with each attachment, and also enables steering without impairing the straightness of the running and performing each work smoothly. Is.

(Structure of the Invention) In the hydraulic circuit of a three-pump hydraulic excavator, the present invention supplies left and right traveling control valves that supply pressure oil to the left and right traveling motors, and supplies pressure oil to actuators of each attachment such as a boom. Input side of the swing control valve that supplies pressure oil to the swing motor by connecting the control valves to the first and second pumps in a state that the control valves for attachment are arranged in the most upstream in tandem. Is connected to the first circuit, and the second circuit is connected to the input side of each attachment control valve downstream of the left and right traveling motors, and the third pump is connected to the second pump during the combined work of traveling and attachment. In the circuit of
The third pump is provided in both the first circuit and the second circuit during combined work of traveling and turning and during combined work of traveling, turning and attachment, and the third pump is provided during non-traveling and turning work. It is characterized in that a selection valve connected to the first circuit is provided.

With this configuration, during traveling work, traveling is prioritized, and pressure oil is individually supplied to the left and right traveling motors from the first and second pumps regardless of whether or not the vehicle is turning or each attachment is operated. The vehicle travels at a speed that corresponds to the switching amount of the traveling control valve and in a steering enabled state without impairing the straightness of the vehicle, and when not traveling, the oil discharged from each pump is the actuator of each attachment such as a boom. And efficiently supplied to the swing motor, and during traveling and combined work of the swing or at least one actuator of each attachment, the discharge oil of the first and second pumps is supplied to the left and right travel motors, The oil discharged from the third pump is supplied to the actuator of each swivel or each attachment,
Each work is done smoothly.

(Example) FIG relief valve 10 incorporated in the control valve V ₁ was in the first pump 1a, one of the travel control valve 11, the boom first speed control valve 12, bucket control valve 13, the arm 2 speed Control valve 14 is connected, the relief valve 20 incorporated in the control valve V ₂ is connected to the second pump 1b, and the other traveling control valve 2
1, the arm 1st speed control valve 22 and the boom 2nd speed control valve 23 are connected, the relief valve 30 and the selection valve 31 are connected to the third pump 1c, and the control valves 11, 12, 13, 14, The actuators for traveling and each attachment, that is, the left and right traveling motors 2a and 2b, the boom cylinder 3, the arm cylinder 4, and the bucket cylinder 5 are connected to 21, 22 and 23, respectively.

In this case, with respect to the first and second pumps 1a and 1b, the left and right traveling control valves 11 and 21 are attached to the attachment control valves 1 such as the boom.
2,13,14 and 22,23 are arranged in tandem in the most upstream position and connected. The second circuit 33 is connected to the input side of the next control valve 12, 22 downstream of each traveling control valve 11, 21, and the second circuit 33 and the first circuit 32 are connected to the output of the selection valve 31. And the first circuit 32 is connected to the swing motor 6 via the swing control valve 34. 15a to 15e, 24a to 24c, 35a to 35c are check valves, 36 is a back pressure valve, and 37 is a shuttle valve.

The control valve block V ₃ has traveling control valves 41, 4 for remotely controlling the control valves V ₁ , V ₂ described above.
2. A boom operation valve 43, an arm operation valve 44, a bucket operation valve 45, and a turning operation valve 46 are provided. Although the pilot ports A _{1 to} A ₇ and B _{1 to} B ₇ on the secondary side of each operation valve are not shown in the figure, the pilot circuit for switching the above control valves and the shuttle valve blocks V ₄ and V ₅ The respective input ports are connected with corresponding reference numerals.

For the shuttle valve blocks V ₄ and V ₅ , the pilot pressure from each of the operation valves 41 to 46 input from the input ports A _{1 to} A ₇ and B _{1 to} B ₇ is selected as high pressure and the input port of the switching block V ₆ is selected. In order to guide the flow rate control unit of each of the pumps 1a to 1c, the shuttle valves 51a to 51i and 52a to 52e, and the sequence valve 53a,
53b and switching valves 54a, 54b are provided. 56 is a pilot circuit that extracts the high-pressure selected pilot pressure from the traveling operation system, 57 is a pilot circuit that extracts the high-pressure selected pilot pressure from the operation system of the boom, arm, and bucket attachments, and 58a and 58b are intermediate circuits between them. , 59a, 59b, 59c are discharge flow rate control circuits of the pumps 1a, 1b, 1c.

The switching valve block V ₆ is provided with first, second, and third switching valves 61, 62, 63. The input side of the first switching valve 61 is connected to the pilot pump 1d, and the output side is connected to the selection valve 31. One of them is connected to the switching pilot circuit 31a, and the output side of the third switching valve 63 is connected to the other switching pilot circuit 31b of the selection valve 31. The first and second switching valves 61 and 62 are switched by the pilot pressure of the traveling operation system guided to the pilot circuit 56, and the third switching valve 63 is switched by the pilot pressure of the turning operation system guided to the pilot circuit 38. ing. 64 is a shuttle valve. A pilot relief valve 60 is connected to the discharge side of the pilot pump 1d, and
Although not shown, the discharge side of 1d is connected to the primary side of each of the operation valves 41 to 46.

Next, the operation will be described.

I. Single traveling work When the traveling levers 41a, 42a are tilted to the left in the drawing, for example,
Pilot pressure is introduced to the secondary ports A ₁ and A ₂ of the travel control valves 41 and 42, and that pressure is introduced to the lower pilot ports A ₁ and A ₂ of the travel control valves 11 and 21. The valves 11 and 21 are switched to the lower position, and the oil discharged from the first and second pumps 1a and 1b is supplied to the travel motors 2a and 2b.

At this time, according to the operation amount of the levers 41a, 42a, the operation valve 4
The pilot pressure guided from 1, 42 is controlled, the spool opening of the traveling control valves 11, 21 is controlled, the inflow flow rate to the traveling motors 2a, 2b is controlled, and the traveling speed is controlled. The pilot pressure from one travel operation valve 41 is guided from the port A ₁ of the shuttle valve block V ₄ to the flow rate control circuit 59a via the shuttle valves 51a and 51e, and the pilot pressure from the other travel operation valve 42. Is guided from the port A ₂ of the shuttle valve block V ₄ to the flow control circuit 59b via the shuttle valves 51b and 51d,
The discharge flow rates of the first and second pumps 1a and 1b are controlled (positive control).

During this traveling work, the shuttle valve block V ₄
The pilot pressure for traveling, which is guided to the ports A ₁ and A _{2 of} , is guided to the circuit 56 from the shuttle valves 51a and 51b through the shuttle valve 51c,
The first and second switching valves 61 and 62 are respectively switched to the right position, and the circuit 31a is communicated with the tank 70. At this time, since the turning operation is not performed, the pressure is not guided to the circuit 38,
The third switching valve 63 is at the position shown in the drawing, and the circuit 31b is in communication with the circuit 57, but since neither of the attachments is operated, pressure is not guided to the circuits 57 and 31b, and the selection valve 31 and the turning control are performed. The valve 34 is held in the neutral position. Therefore, the oil discharged from the third pump 1c is guided from the neutral position of the selection valve 31 to the first circuit 32 and the second circuit 33. However, since the second circuit 33 is blocked by the control valve of each attachment, the oil discharged from the third pump 1c is returned from the first circuit 32 to the tank 70 via the neutral position of the turning control valve 34. Further, in this case, since the pressure is not guided to the circuit 59c, the discharge flow rate of the third pump 1c is controlled to the minimum.

In this way, during traveling alone work, the discharge oil of the third pump 1c is controlled to the minimum flow rate and returned to the tank 70 while
The oil discharged from the pumps 1a, 1b is supplied to the left and right traveling motors 2a, 2b, and the inflow flow rate to the respective motors 2a, 2b and the first and second pumps 1 according to the operation amount of the traveling levers 41a, 42a.
The discharge flow rates of a and 1b can be controlled to efficiently perform traveling work.

II. Work on the attachment When not running, attach the attachment, for example the boom lever.
When 43a is tilted to the right in the drawing, the pilot pressure corresponding to the lever operation amount is applied to the secondary side ports B ₅ , B _{4 of the} boom operation valve 43.
To boom first speed control valve 12 and boom second speed control valve 23
Of each pilot port B ₅ and B ₄ .

Here, when the operation amount of the lever 43a is the first speed of the boom, only the boom first speed control valve 12 is switched to the upper position, and the first pump
Only the discharge oil of 1a is supplied to the boom cylinder 3. At this time, the boom pilot pressure is guided from the port B ₅ of the shuttle valve block V ₅ to the circuits 58a and 58b via the shuttle valves 52a, 52c and 52d. Then, the pilot pressure introduced to the circuit 58a is led to the circuit 59a via the switching valve 54b of the shuttle valve block V _4, the shuttle valve 51e, the discharge flow rate of the first pump 1a is controlled.

Further, during the first speed of the boom, the control valve 23 for the second speed of the boom is kept in the neutral position, and the oil discharged from the second pump 1b passes through the control valve V ₂ and is returned to the tank 70. In this case, the pilot pressure of the boom is also guided to the port B ₄ of the shuttle valve block V ₄ , but the sequence valve 53a remains in the position shown in the figure, and the pressure is not guided to the circuit 59b, and the discharge of the second pump 1b. The flow rate is controlled to a minimum.

Next, when the boom lever 43a is tilted to the second speed of the boom, the control valve 23 for the second speed of the boom is also switched to the upper position, and the second pump 1b
The discharge oil from the first pump 1a merges with the discharge oil from the first pump 1a and is supplied to the boom cylinder 3. At this time, the boom operation valve
Pilot pressure from 43 is port of shuttle valve block V ₄
From B ₄ via the shuttle valve 51i to the sequence valve 53a,
While the valve 53a is switched to the left position, the pilot pressure is guided to the circuit 59b via the shuttle valve 51g, the switching valve 54a and the shuttle valve 51d, and the discharge flow rate of the second pump 1b is controlled. As a result, the boom cylinder 3 is extended at the first speed or the second speed of the boom according to the operation amount of the lever, and the boom raising work is performed.

Since the traveling and turning are not operated during the boom work, the first to third switching valves 61 to 63 are at the positions shown in the drawing, and the boom pilot pressure guided to the circuit 58b is the shuttle valve 51h. , Circuit 57, and circuit 31b via the third switching valve 63
The primary pressure from the pilot pump 1d is
Since it is guided to the circuit 31a via the switching valve 61, the selection valve 31 is switched to the lower position. Therefore, the oil discharged from the third pump 1c is returned to the tank 70 via the second circuit 33 and the turning control valve 34. Also, since no pressure is introduced to the circuit 59c, the third
The discharge flow rate of the pump 1c is controlled to the minimum.

Thus, when performing boom work in the non-traveling state, pressure oil is supplied to the boom cylinder 3 from the first pump 1a or both the first pump 1a and the second pump 1b, and the remaining pumps 1c or 1c and 1b are supplied. The discharged oil can be controlled to the minimum flow rate and returned to the tank 70 to efficiently perform the boom work.

It should be noted that the same control as described above is performed when the arm 1st speed, the 2nd speed, and the bucket work are performed in the non-traveling state.

III. Single swing operation When the swing lever 46a is tilted to the left in the drawing, for example, in the non-traveling state, pilot pressure is introduced from the secondary port on the left side of the swing operation valve 46, and the swing control valve 34 is in the left position. Is switched to. Further, the pilot pressure for turning is guided to the circuit 38 via the shuttle valve 37, the third switching valve 63 is switched to the right position, and the circuit 31b is connected to the tank 70. At this time, since the traveling and the attachment are not operated, the pilot pressure is not guided to the circuit 56 and the circuit 57, the first and second switching valves 61 and 62 are at the positions shown in the drawing, and the primary pressure from the pilot pump 1d. The pressure is guided to the circuit 31a through the first switching valve 61, and the selection valve 31 is switched to the lower position. Therefore, the third pump
The discharge oil of 1c is supplied to the swing motor 6 from the lower position of the selection valve 31 through the first circuit 32 and the swing control valve 34.

Further, in this case, the pilot pressure guided from the swing operation valve 46 and the spool opening of the swing control valve 34 are controlled according to the operation amount of the swing operation lever 46a, the flow rate into the swing motor 6 is controlled, and the swing speed is controlled. Is controlled, and the swirling pilot pressure guided to the circuit 38 is guided to the circuit 59c via the shuttle valve 64 to control the discharge flow rate of the third pump 1c.

Also, since the traveling and attachments are not operated during this single swing operation, the control valve
Each control valve in V ₁ , V _{2 is} in the position shown and circuit 59
Since the pilot pressure is not guided to a and 59b, the discharge oil of the first and second pumps 1a and 1b is returned to the tank 70 through the control valves V ₁ and V ₂ while being controlled to the minimum flow rate. Be done.

In this way, when performing the single swing operation, the first and second pumps 1a, 1b
While controlling the discharge oil of to the minimum flow rate and returning it to the tank 70,
The discharge oil of the third pump 1c is supplied to the swing motor 6, and
By controlling the inflow flow rate to the swing motor 6 and the discharge flow rate of the third pump 1c according to the operation amount of the swing lever 46a, the swing work can be efficiently performed.

IV. Combined work of traveling and attachment When the above-mentioned traveling alone work of I, the attachment, for example, the boom lever 43a is tilted to the right in the drawing, pilot pressure is introduced from the secondary side port B _{5 of} the boom operation valve 43,
The pilot pressure switches the boom first speed control valve 12 to the upper position. However, this boom first speed control valve 12
Since the traveling control valve 11 is arranged in tandem on the upstream side of and the traveling control valve 11 is switched by the traveling pilot pressure, the discharge oil of the first pump 1a is supplied only to one traveling motor 2a. The supplied oil is not supplied from the first pump 1a to the boom first speed side, and the boom cylinder 3 is supplied with pressure oil from the third pump 1c.

That is, at the same time the boom first speed control valve 12 is switched by the pilot pressure of the boom, the pilot pressure is led to the circuit 58b via a shuttle valve block V _5, is led to the circuit 57 further via the shuttle valve 51h . At this time, the first and second switching valves 61, 62 are switched to the right position by the traveling pilot pressure, the circuit 31a is in communication with the tank 70, and the turning is not operated, so the third switching valve 63 Is held in the illustrated position. Therefore, the circuit 57
The pilot pressure introduced to the circuit passes through the third switching valve 63 and the circuit 31b.
, The selection valve 31 is switched to the upper position, and the third pump
The discharged oil of 1c is guided to the boom cylinder 3 through the second circuit 33, the check valves 15c and 15d, and the boom first speed control valve 12.

Further, in this case, the pilot pressure guided to the circuit 57 is guided to the circuit 59c via the second switching valve 62 and the shuttle valve 64, and the discharge flow rate of the third pump 1c is controlled.

At the time of the composite work of the traveling and boom raising, the pilot pressure of the boom is guided to the circuit 58a via the shuttle valve block V _5, since the switching valve 54b is switched to the left position by the pilot pressure of the running The boom pilot pressure is not guided to the flow rate control unit of the first pump 1a. Further, when the boom lever 43a is operated to the second speed of the boom, the control valve 23 for the second speed of the boom is also switched, but the traveling control valve 21 is arranged in tandem upstream of the control valve 23, and Since the control valve 21 is switched by the traveling pilot pressure, the oil discharged from the first pump 1a is supplied only to the other traveling motor 2b, and the second pump 1b is supplied.
Oil does not flow into the boom second speed control valve 23. Further, when the boom is operated up to the 2nd speed, the pilot pressure is guided to the port B ₄ of the shuttle valve block V ₄ , but since the switching valve 54a is switched to the right position by the traveling pilot pressure, the boom pilot pressure is changed. Is not guided to the flow rate control unit of the second pump 1b. As a result, the discharge oil of the first and second pumps 1a, 1b is controlled in flow rate only by the traveling pilot pressure, and the discharge oil is appropriately supplied to the left and right traveling motors 2a, 2b.

In this way, the traveling motor
Since pressure oil is supplied to the 2a and 2b from the first and second pumps 1a and 1b, and pressure oil is supplied to the boom cylinder 3 from the third pump 1c,
Even if the boom is operated during traveling work, there is no fear that the supply flow rate to the traveling motors 2a, 2b, that is, traveling speed, will extremely decrease, and the straightness of traveling will not be impaired. Moreover,
By operating the traveling levers 41a, 42a, steering for left and right traveling can be arbitrarily performed, and both traveling and boom raising can be performed without any trouble.

It should be noted that the same control as described above is performed during the combined work of traveling and the arm or bucket.

V. Combined work of traveling and turning When the turning lever 46a is tilted to the left during the above-mentioned single traveling work, the turning control valve 34 is switched to the left position by the turning pilot pressure by the same action as the above IV. At the same time, the pilot pressure passes through the shuttle valve 37 and the circuit 38.
The third switching valve 63 is switched to the right position, and the circuit 31
b is communicated with the tank 70. In this case, the pilot pressure of the above traveling is guided to the circuit 56 through the shuttle valve block V ₄ , the first and second switching valves 61 and 62 are switched to the right position, and the circuit 3
1a communicates with the tank 70. For this reason, the selection valve 31 is held in the neutral position, and the oil discharged from the third pump 1c remains in the selection valve 31.
It is guided from the neutral position to the first circuit 32 and the second circuit 33. However, since the attachments are not operated at this time, the second circuit 33 is blocked by the control valve of each attachment, so that the oil discharged from the third pump 1c is swirled through the first circuit 32 and the swirl control valve 34. It is supplied to the motor 6.

Further, in this case, the turning pilot pressure guided to the circuit 38 is guided to the circuit 59c via the shuttle valve 64, and the discharge flow rate of the third pump 1c is controlled.

During this combined work of traveling and turning, pressure oil is supplied to the turning motor 6 from the third pump 1c, and pressure oil is supplied to the running motors 2a and 2b individually from the first and second pumps 1a and 1b. Therefore, the traveling and the turning can be performed independently of each other without any trouble as in the case of the above-mentioned IV complex work.

VI. Combined work of traveling, turning, and attachment In the above-described combined work of traveling and turning, if the boom lever 43a is tilted to the left in the drawing, for example, the boom pilot pressure causes the boom first speed control valve 12 to move downward. A part of the discharge oil of the third pump 1c, which is switched to the position and guided to the second circuit 33 via the neutral position of the selection valve 31 by the above V, is supplied to the boom cylinder 3 via the boom first speed control valve 12. To be done.

In this case, at the neutral position of the selection valve 31, the throttle 31 is placed on the second circuit side.
Since c is provided, the discharge oil of the third pump 1c is the selection valve 31
Is preferentially supplied to the boom circuit 3 via the second circuit 33 and the boom 1st speed control valve 12 from the first circuit side, that is, the swing motor 6 side. The motor 6 and the boom cylinder 3 are operated without any hindrance. Further, during this operation, the first and second switching valves 61, 62 are switched to the right position by the traveling pilot pressure, so that the circuit 57 is operated from the boom operation valve 43 through the shuttle valve blocks V ₅ , V _4. High pressure is selected by the shuttle valve 64 for the boom pilot pressure guided to the circuit 38 and the swing pilot pressure guided to the circuit 38, and is guided to the circuit 59c. By the boom and swing high pressure side pilot pressure, the third pump 1c
The discharge flow rate of is controlled.

It should be noted that the same control as described above is performed during combined work of traveling, turning, and other attachments such as arms and buckets.

In this way, even during the combined work of traveling, turning and attachment, the traveling motors 2a and 2b are individually supplied with pressure oil from the first and second pumps 1a and 1b, and the turning motor 6 and the attachment are supplied from the third pump 1c. By supplying the pressure oil, it is possible to perform the traveling, turning, and attachment work without any trouble.

(Effects of the Invention) The present invention supplies the pressure oil individually from the first and second pumps to the left and right traveling motors during traveling work regardless of whether or not the vehicle is turning or operating each attachment. In the swivel or combined work with at least one actuator of each attachment, the discharge oil of the third pump is supplied to the swivel or each actuator of the attachment. Even if an operation is performed, it is possible to travel at a speed according to the switching amount of the travel control valve and in a steerable state without impairing the straightness of travel. Further, when the vehicle is not traveling, the discharge oil of each pump can be supplied to the actuator and the swing motor of each attachment such as a boom, so that the traveling, the swing, and the individual and combined work of each attachment can be performed smoothly and efficiently. .

[Brief description of drawings]

The drawing is a hydraulic circuit diagram showing an embodiment of the present invention. 1a ... 1st pump, 1b ... 2nd pump, 1c ... 3rd pump, 2
a, 2b ... Left and right traveling motors, 3 ... Boom cylinders, 4 ... Arm cylinders, 5 ... Bucket cylinders, 6 ... Swing motors, 11 ... Traveling control valves, 12 ... Boom first speed control valves, 13 ...
Bucket control valve, 14 ... Arm control valve, 21 ... Travel control valve, 22 ... Arm first speed control valve, 23 ... Boom second speed control valve, 31 ... Selection valve, 32 ... First circuit, 33 … Second circuit, 34
... Swirling control valve, 37, 51a to 51i, 52a to 52e, 64 ... Shuttle valve, 61, 62, 63 ... First, second, third switching valve.

Claims (1)

[Claims] 1. In a hydraulic circuit of a three-pump hydraulic excavator, left and right traveling control valves for supplying pressure oil to the left and right traveling motors, and attachments for supplying pressure oil to actuators of attachments such as booms. The control valves are connected to the first and second pumps in a state of being arranged in the most upstream in tandem with respect to the control valve, and the input side of the swing control valve for supplying pressure oil to the swing motor is set to the first side. In addition to connecting to the circuit, a second circuit is connected to the input side of each attachment control valve downstream of the left and right traveling motors, and the third pump is provided to the second circuit during the combined work of traveling and attachment. The third pump is provided in both the first circuit and the second circuit during combined work of traveling and turning and during combined work of traveling, turning and attachment, and the third pump is provided during non-traveling and turning work. Circuit of 1 Hydraulic circuit of a hydraulic excavator, characterized in that a selected valve to be connected.