JPH05287779A - Hydraulic circuit construction of operation vehicle - Google Patents

Abstract

PURPOSE:To constitute simply a detection system in a state to drive an operating device during the advancement of a hydraulic detection system only, in hydraulic circuit construction of an operation vehicle constituted so as to supply hydraulic fluid to an operating device controlling valve from a third pump, in the case a hydraulic device controlling valve and a hydraulic actuator controlling valve are connected to first and second pumps respectively and, at the same time, the operating device is driven during the advancement by driving right and left hydraulic traveling devices. CONSTITUTION:A pair of pilot oil paths 35 and 36 connected in series are provided to hydraulic traveling device controlling valves 13, 18 and hydraulic actuator controlling valves 15, 19 and 21. When an operating device is driven during the advancement to cut-off both sides of the pilot oil paths 35 and 36, pilot pressure generates in the pilot oil paths 35 and 36. A selector valve of the third pump is switched and operated by the pilot pressure, and hydraulic fluid of the third pump is supplied to hydraulic actuator controlling valves 15, 19 and 21. Part of the hydraulic fluid of the third pump as the pilot pressure supplied to the pilot oil paths 35 and 36 is utilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit structure for a work vehicle provided with a pair of left and right hydraulic traveling devices.

[0002]

2. Description of the Related Art In a work vehicle having a pair of left and right crawler type traveling devices (types in which crawlers are driven by hydraulic motors), which are an example of hydraulic traveling devices, a hydraulic circuit structure as shown in, for example, FIGS. Some are equipped with. In the structure shown in FIGS. 8 and 9, the hydraulic oil from the first pump 51 and the second pump 52 is first supplied to the control valve 53 for the traveling device, and the lower side of the control valve 53 is used for driving the working device. The control valves 54 of the center bypass type are connected in parallel.

In this structure, since the control valve 54 for the working device is located below the control valve 53 for the traveling device,
When it is desired to drive the work device while driving the left and right traveling devices to move straight, the working oil for driving the work device may be insufficient and the work device may not be sufficiently driven. On the other hand, if the working oil is deprived of the working device in this state, the rotation of the hydraulic motor for the traveling device on one side may decrease, and the machine body may face diagonally. Therefore, in the structure of FIGS. 8 and 9, when the work device is to be driven while the left and right traveling devices are being driven, the hydraulic fluid from another third pump 55 is caused to travel by the switching valve 56. The control valve 53 for the apparatus is replenished to the lower side of the apparatus at a proper time to make up for the shortage of hydraulic oil on the working apparatus side.

When replenishing hydraulic oil to the working device side while traveling straight as in the structures of FIGS. 8 and 9, there is a structure for detecting that the working device is driven while the left and right traveling devices are being driven. is necessary. In this case, the pair of limit switches 57 for detecting that the control valves 53 for the left and right traveling devices are switched from the neutral position to the operating position, and one of the hydraulic actuators for the working device are controlled by the control valve 54. A pilot oil passage system 58 is provided for taking out pilot pressure from the hydraulic oil when the hydraulic oil is supplied. As a result, when the electrical detection signal from the pair of limit switches 57 and the hydraulic detection signal from the pilot oil passage system 58 are input to the control device 59, the switching device 56 is operated by the control device 59. It is configured to be operated on the oil supply side. In this way, the switching operation of the control valve 53 for the traveling device is performed by the contact type limit switch 5
The reason why the control valve 53 is 7 is that the control valve 53 itself is often a mechanical operation type in which it is directly connected to an operation lever or the like by a link. The reason why the drive of the work device is detected by the pilot pressure is that there are many pilot operation types in which the control valve 54 for the work device is switched by the pilot pressure.

[0005]

As described above, in the structure shown in FIGS. 8 and 9, an electrical structure is used to detect that the working device is driven while the left and right traveling devices are being driven. Detection system (system of limit switch 57)
And a hydraulic detection system (pilot oil passage system 58). As described above, if the hydraulic circuit structure is provided with two systems, an electrical detection system and a hydraulic detection system, the structure becomes complicated. Therefore, the structure of the detection system is simplified. There is room for The present invention simplifies the structure of a detection system that detects that a working device is driven while the left and right traveling devices are being driven when hydraulic oil is replenished to the hydraulic actuator side for the working device while traveling straight ahead. The purpose is to.

[0006]

The features of the present invention are as follows in the hydraulic circuit structure of a work vehicle as described above.
It is provided with the configuration described in [C]. That is, [a] The hydraulic traveling device control valve and the hydraulic actuator control valve are connected in series, and the hydraulic traveling device control valve and the hydraulic actuator control valve are in the neutral position. When the control valve is operated to the operating position, it is shut off by the spool of the control valve, and is a pair of pilot oil passages provided in each of the first and second pump systems. [A] A third pump that supplies hydraulic oil to a hydraulic actuator different from the hydraulic actuators of the first and second pump systems, and the hydraulic oil of this third pump for the hydraulic actuators of the first and second pumps. A pilot-operated switching valve that can be switched to a state in which it is supplied to a control valve, and a pilot oil passage that extracts pilot pressure from the hydraulic oil supply system of the third pump and supplies it to a pair of pilot oil passages. [C] The pair of pilot oil passages are connected to each of the portions between the control valve for the hydraulic traveling device and the control valve for the adjacent hydraulic actuator. A pair of auxiliary pilot oil passages for switching the switching valve to a state in which the hydraulic oil is supplied to the control valves for the hydraulic actuators of the first and second pumps, by the pilot pressure of at least one of the set values.

[0007]

When configured as described above, as shown in FIGS. 1 and 2, for example, the control valves 13, 18 of the left and right hydraulic traveling devices are shown.
In the operating position (the left and right hydraulic traveling devices are driven to move the machine body straight) (in the state where the pair of pilot oil passages 35 and 36 are cut off at the positions of the control valves 13 and 18), It is assumed that the control valves 15, 19, 21 for the working device are operated from the neutral position to the operating position. When such an operation is performed, with the pair of pilot oil passages 35, 36 being blocked at the positions of the control valves 13, 18 for the hydraulic traveling device, the control valves 15, 19, 21 for the working device are operated. Even in the position, the pair of pilot oil passages 35 and 36 are shut off. As a result, the pilot pressure cannot pass through the pair of pilot oil passages 35 and 36, so that a pilot pressure higher than the set value is generated in the pair of pilot oil passages 35 and 36, and this pilot pressure becomes an auxiliary pilot oil passage. It is supplied to the switching valve 31 from the passage 38 and the switching valve 31 is switched. Therefore, the hydraulic oil from the third pump 22 is supplied to the control valves 15, 19, 21 for the working device via the switching valve 31.

On the other hand, for example, the control valves 13 and 18 for the hydraulic traveling device and the control valves 15 and 19 for the working device,
21 is operated to the neutral position, the control valves 13 and 18 of the hydraulic traveling device are operated to the neutral position, and the control valves 15, 19 and 21 for the working device are operated to the operating position, and In a state other than the above-mentioned state such as a state in which the control valves 13, 18 of the hydraulic traveling device are operated to the operating position and the control valves 15, 19, 21 for the working device are operated to the neutral position,
Since the pilot pressure passes through the pair of pilot oil passages 35, 36, the pilot pressure above the set value is not generated and the switching valve 31 is not switched.

As described above, when replenishing hydraulic oil to the hydraulic actuator side for the working device while traveling straight ahead, a detection system for detecting that the working device is driven while the left and right traveling devices are being driven. As shown in FIG. 8 and FIG.
While the conventional structure shown in FIG. 2 is provided with two systems, an electrical detection system and a hydraulic detection system, the present invention requires only one system of a hydraulic detection system (pilot pressure system). .. In the case of the center bypass type control valve as described above, there is a case where each control valve is installed inside one block, and the spools are arranged side by side in parallel so that they are manufactured as one hydraulic unit. Many. Therefore, the pair of pilot oil passages according to the present invention can be easily formed by drilling or the like that penetrates the block and each control valve. When supplying the pilot pressure for the switching operation of the switching valve to the pair of pilot oil passages, a part of the hydraulic oil from the third pump is taken out and supplied as the pilot pressure. There is no need for a dedicated pilot pump or the like to supply pilot pressure to.

[0010]

As described above, the two systems of the electrical detection system and the hydraulic detection system can be unified into one system of the hydraulic detection system, and the hydraulic circuit of the work vehicle can be simplified. It is now possible to reduce the manufacturing cost. In the case of the control valve of the center bypass type, the pilot oil passage of the present invention can be formed relatively easily, so that the manufacturing cost can be suppressed in terms of processing. Further, since a pilot pump for supplying pilot pressure is not required, the hydraulic circuit can be simplified and the manufacturing cost can be suppressed in this respect as well.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 5, a swivel base 2 is supported on the upper part of a pair of left and right crawler type traveling devices 1 (corresponding to a hydraulic traveling device), and a backhoe device 3 is provided in front of the swivel base 2 to provide a work vehicle. It constitutes a backhoe as an example. The backhoe device 3 includes a boom 4 vertically rocked by a first hydraulic cylinder 7 (corresponding to a hydraulic actuator), an arm 5 rockable back and forth by a second hydraulic cylinder 8 (corresponding to a hydraulic actuator), And a bucket 6 driven by a third hydraulic cylinder 9 (corresponding to a hydraulic actuator) so as to be swung in and swung. The backhoe device 3 as a whole is swingable around the vertical axis P1 of the front part of the swivel base 2, and a fourth hydraulic cylinder 28 for swinging the backhoe device 3 is provided.

Next, the first, second, third, fourth hydraulic cylinders 7,
The hydraulic circuit structure for 8, 9, and 28 will be described.
As shown in FIG. 1, in the oil passage 11 from the first pump 10,
A control valve 13 for a hydraulic motor (not shown) of the right traveling device 1 is connected to the oil passage 12 on the lower side of the control valve 13,
A control valve 15 is connected to the second hydraulic cylinder 8 (see FIG. 5) for the arm 5. And the second pump 16
The control valve 18 for the hydraulic motor (not shown) of the left traveling device 1 is connected to the oil passage 17 from the third hydraulic cylinder 9 (for the bucket 6) to the oil passages 14 and 20 from the control valve 18. 5) and a control valve 21 for the first hydraulic cylinder 7 for the boom 4 (see FIG. 5).
Are connected in parallel.

The control valves 13, 15, 18, 19, 21 for the traveling device 1 and the backhoe device 3 are of the center bypass type. The control valves 13 and 18 for the traveling device are mechanically-operated mechanically directly connected to the traveling lever 30 by a link or the like, and are directly operated by the pair of left and right traveling levers 30. Then, the control valve 15 for the backhoe device 3,
Reference numerals 19 and 21 are pilot-operated types that are switched by pilot pressure, and are switched by pilot pressure generated based on the operation of an operating lever (not shown).

As shown in FIG. 2, a control valve for a hydraulic motor (not shown) for the swivel 2 (corresponding to another hydraulic actuator) for the third pump 22 via oil passages 23, 24, 41. 26, a control valve 29 for a fourth hydraulic cylinder 28 (corresponding to another hydraulic actuator) for swinging the backhoe device 3, and a fifth hydraulic cylinder 4 for the dozer 27 of FIG.
Control valve 4 for 0 (equivalent to another hydraulic actuator)
2 are connected in parallel. Control valves 26, 29, 42
Is a center bypass type, and is a pilot operated type that is switched by pilot pressure. Then, the switching valve 31 is connected to the center oil discharge passage 25 of the control valves 26, 29, 42.
Are connected.

Next, when the backhoe device 3 is driven while the left and right traveling devices 1 are being driven, the third pump 2
A structure for replenishing the hydraulic oil from 2 to the backhoe device 3 side will be described. As shown in FIGS. 1 and 2, in the center oil discharge passage 25 on the third pump 22 side, the oil passage 32 from the portion between the control valve 42 and the switching valve 31 is the oil passages 33, 34.
And is connected to the oil passage 12 on the first pump 10 side and the oil passages 14 and 20 on the second pump 16 side. As shown in FIG. 2, the switching valve 31 is a relief valve type in which the valve body 31a is lightly biased toward the closed side by a spring 31b, and the valve body 31a is opened by supplying pilot pressure to the oil chamber 31c on the spring 31b side. It is a pilot operated type that can be maintained in a completely closed state. In a normal state where the pilot pressure is not supplied to the oil chamber 31c, the working oil from the center oil discharge passage 25 is discharged to the tank, and the work by the control valves 26, 29, 42 can be performed without any trouble. To the extent that pilot pressure for the passage 37 is secured at least, the switching valve 3
That is, the first valve element 31a is biased to the closing side.

On the other hand, the first and second pumps 10, 1
The 6-side control valves 13, 15, 18, 19, 21 are installed in one block, and the spools are arranged side by side so that they are parallel to each other. First and second pumps 10,
Each of 16 is provided with a pilot oil passage 35 penetrating the control valves 13 and 15 in series and a pilot oil passage 36 penetrating the control valves 18, 19 and 21 in series.
As shown in FIGS. 3 and 4, in the control valves 13 and 18, pilot oil passages 35 and 36 are opened on the block side, and annular grooves 13b and 18b are formed in the spools 13a and 18a. The control valves 15, 19, 21 are also formed, and the pilot oil passages 35, 36 are formed by linearly connecting these structures.

When the control valves 13, 15, 18, 19, 21 are operated to the neutral positions as shown in FIGS. 1, 3, 4, the spools 13 of the control valves 13, 15, 18, 19, 21 are controlled.
The annular grooves 13b and 18b of a and 18a are located at the pilot oil passages 35 and 36, respectively.
5, 36 are in communication. And the control valves 13, 1
When 5, 18, 19, 21 are switched from the neutral position shown in FIG. 1 to the operating position, the annular grooves 13b, 18b of the spools 13a, 18a are disengaged from the pilot oil passages 35, 36 to one side, and the control thereof is performed. Valves 13, 15, 18, 19,
At position 21, the pilot oil passages 35 and 36 are shut off.

As shown in FIGS. 1 and 2, the auxiliary pilot oil passage 38 branched into a pair of left and right is connected to the pilot oil passage 35.
Between the control valve 13 for the traveling device 1 and the control valve 15 for the arm 5 in the above, and the control valve 18 for the traveling device 1 and the control valve 1 for the bucket 6 in the pilot oil passage 36.
9, and the auxiliary pilot oil passage 38 is connected to the oil chamber 31c of the switching valve 31. Then, in the center oil discharge passage 25 on the side of the third pump 22, a pilot oil passage 37 is connected to a portion between the control valve 42 and the switching valve 31, and the pilot oil passage 37 is branched into a pair of left and right to form an auxiliary pilot. It is connected to the oil passage 38, and a pair of throttle portions 39 is provided at the position shown in FIG. As a result, part of the hydraulic oil from the third pump 22 is taken out as pilot pressure and is supplied to the pair of pilot oil passages 35 and 36 via the pilot oil passage 37.

With the above structure, the first and second pumps 1
As shown in FIG. 1 on the 0, 16 side, when the control valves 13, 18 for the left and right traveling devices 1 and the control valves 15, 19, 21 for the backhoe device 3 are not operated from the neutral position, Since the pilot pressure from the pump 22 returns to the tank through both pilot oil passages 35 and 36, the switching valve 31
Is not operated in the fully closed position.

While the control valves 13, 18 of the left and right traveling devices 1 are being operated to the neutral position (the left and right traveling devices 1 are stopped), the control valves 15, 19, 2 for the backhoe device 3 are operated.
If the pilot oil passages 35, 36 are shut off at the positions of the control valves 15, 19, 21 by operating 1 in the operating position,
The pilot pressure from the pump 22 is applied to both pilot oil passages 3
Since the valves 5 and 36 pass through the control valves 13 and 18 of the traveling apparatus 1 and return to the tank, the switching valve 31 is not operated to the completely closed position.

On the contrary, the control valves 13, 1 of the left and right traveling devices 1
8 is operated to the operating position (the left and right traveling devices 1 are driven and the machine body goes straight) (the pilot oil passages 35 and 36 are shut off at the positions of the control valves 13 and 18), the backhoe device. Unless the control valves 15, 19, 21 for 3 are operated from the neutral position, the pilot pressure from the third pump 22 causes the control valves 15, 19, 21 side of the backhoe device 3 in both pilot oil passages 35, 36 to operate. Since it returns to the passing tank, the switching valve 31 is not operated to the completely closed position.

Then, the control valves 13 of the left and right traveling devices 1,
In a state where 18 is operated to an operating position (the left and right traveling devices 1 are driven and the machine body goes straight) (a state where the pilot oil passages 35 and 36 are cut off at the positions of the control valves 13 and 18), the backhoe device It is assumed that the control valves 15, 19, 21 for 3 are operated from the neutral position to the operating position. When such an operation is performed, in the state where the pilot oil passages 35 and 36 are shut off at the positions of the control valves 13 and 18 for the traveling device 1, at the positions of the control valves 15, 19, and 21 for the backhoe device 3. Also, the pilot oil passages 35 and 36 are shut off.

As a result, the pilot pressure from the third pump 22 cannot escape to the tank through the pilot oil passages 35 and 36, so that the pilot pressure is supplied from the auxiliary pilot oil passage 38 to the oil chamber 31c of the switching valve 31. Thus, the switching valve 31 is operated to the completely closed position. Therefore, the hydraulic oil from the center oil discharge passage 25 of the third pump 22 is transferred to the oil passage 3
It is supplied to the control valves 15, 19, 21 for the backhoe device 3 via 2, 33, 34.

[Other Embodiments] The hydraulic circuits shown in FIGS. 1 and 2 may be configured as shown in FIGS. 6 and 7. In the structure shown in FIGS. 6 and 7, the pilot oil passage 37 of FIG.
Not from the center oil drain 25 of the third pump 22
It is branched from the oil passages 33 and 34 and is connected to the pair of auxiliary pilot oil passages 38, and the throttle portion 3 is connected to the pilot oil passage 37.
9 is equipped. Then, the switching valve 31 as shown in FIG.
Instead of using the center oil discharge passage 25 of the third pump 22, as shown in FIG.
Connect to the oil passage 32 as shown in FIG. In the normal state, the switching valve 31 is in the lightly closed state, and the third pump 22
Regarding the pressure of the hydraulic oil from the center oil discharge passage 25, a part of the hydraulic oil is used as pilot pressure in the pilot oil passages 35, 3
6 is maintained so that it is supplied to the oil passages 6, and the pressure is not such that it is supplied to the oil passages 12, 14, 20 on the first and second pumps 19, 16 side.

With the above structure, the first and second pumps 1
On the 0, 16 side, the control valves 13, 18 for the traveling device 1
And a state in which the control valves 15, 19, 21 for the backhoe device 3 are operated to the neutral position, the control valve 13, of the traveling device 1,
Control valve 1 for backhoe device 3 by operating 18 to the neutral position
The state where 5, 19, 21 are operated to the operating position, and
In the state where the control valves 13, 18 of the traveling device 1 are operated to the operating position and the control valves 15, 19, 21 for the backhoe device 3 are operated to the neutral position, the pilot pressure passes through both pilot oil passages 35, 36. Since it returns to the tank, the switching valve 31 is not operated to the completely closed position, and the hydraulic oil from the center oil discharge passage 25 of the third pump 22 is supplied to the control valves 15, 19, 21 for the backhoe device 3. There is no such thing.

On the contrary, the control valves 13, 1 of the left and right traveling devices 1
8 is operated to the operating position (the left and right traveling devices 1 are driven and the machine body goes straight) (the pilot oil passages 35 and 36 are shut off at the positions of the control valves 13 and 18), the backhoe device. It is assumed that the control valves 15, 19, 21 for 3 are operated from the neutral position to the operating position. If such an operation is performed, the pilot pressure from the third pump 22 cannot escape to the tank through the pilot oil passages 35 and 36, so that the pilot pressure from the auxiliary pilot oil passage 38 to the oil chamber 31c ( (See FIG. 2), the switching valve 31 is operated to a completely closed position. Therefore, the hydraulic oil from the center oil discharge passage 25 of the third pump 22 is transferred to the oil passage 32,
Control valve 1 for backhoe device 3 via 33, 34
It is supplied to 5, 19, and 21.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of first and second pump sides.

FIG. 2 is a hydraulic circuit diagram of the third pump side.

FIG. 3 is a vertical sectional side view of a control valve for a traveling device.

FIG. 4 is an enlarged view of an area around an annular groove of a spool and a pilot oil passage in a control valve for a traveling device.

[Fig. 5] Overall side view of the backhoe

FIG. 6 is a hydraulic circuit diagram of first and second pump sides in another embodiment.

FIG. 7 is a hydraulic circuit diagram of a third pump side in another embodiment.

FIG. 8 is a hydraulic circuit diagram of the first and second pump sides in the conventional structure.

FIG. 9 is a hydraulic circuit diagram of the third pump side in the conventional structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic traveling device 7,8,9 Hydraulic actuator 10 First pump 13,18 Control valve 13a for hydraulic traveling device 13a, 18a Spool of control valve 15,19,21 Control valve 16 for hydraulic actuator 16 Second pump 22 Third pump 28, 40 Hydraulic actuator for each 31 Switching valve 35, 36 Pair of pilot oil passage 37 Pilot oil passage 38 Auxiliary pilot oil passage

Claims (1)

[Claims] 1. A first pump (10) and a second pump (1)
A pair of left and right control valves (13), (18) for the hydraulic traveling device (1) are connected to each of the uppermost side portions of 6), and the pair of control valves (13), (18) are connected. A plurality of center bypass type control valves (15), (1) for the hydraulic actuators (7), (8), (9) respectively
9), (21) is a hydraulic circuit structure of a working vehicle in which the hydraulic circuit structure of the working vehicle is connected in parallel, the hydraulic circuit structure of the working vehicle having the configurations described in [A] to [C] below. [A] Control valve (13) for the hydraulic traveling device (1),
(18) and hydraulic actuators (7), (8),
The control valves (13), (18) and the hydraulic actuator (for the hydraulic traveling device (1), which are connected in series to the control valves (15), (19), (21) for the (9), and the hydraulic actuator ( 7),
Control valves (15), (19), (2) for (8), (9)
1) When the control valve (1
3), (15), (18), (19), (21) are operated to the operating position, the control valves (13), (15), (1)
8), (19), (21) spools (13a), (1
8a), the first and second
A pair of pilot oil passages (35) and (36) provided in each of the pumps (10) and (16) systems. [B] Supplying hydraulic oil to hydraulic actuators (28) and (40) different from the hydraulic actuators (7), (8) and (9) of the first and second pumps (10) and (16) systems. And a third pump (22) for operating the hydraulic oil of the third pump (22) for the hydraulic actuators (7), (8), (9) in the first and second pumps (10), (16). A pilot operated switching valve (31) that can be switched to a state in which it is supplied to each control valve (15), (19), (21);
The pilot pressure is taken out from the hydraulic oil supply system of the third pump (22), and the pair of pilot oil passages (35),
Pilot oil passage (37) to supply (36). [C] In the pair of pilot oil passages (35) and (36), the control valve (1) for the hydraulic traveling device (1)
3), (18) and the hydraulic actuator (8) next to this,
The control valve (15) for (9), which is connected to each of the portions between (19), and the set value of at least one of the pair of pilot oil passages (35), (36). With the above pilot pressure, the switching valve (31) controls the control valves (15), () for the hydraulic actuators (7), (8), (9) of the first and second pumps (10), (16). 1
9), a pair of auxiliary pilot oil passages (38) for switching operation to supply hydraulic oil to (21).