JPH05287778A - 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.

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 A working vehicle having a pair of left and right crawler type traveling devices (types in which a crawler is driven by a hydraulic motor), which is an example of a hydraulic traveling device, has a hydraulic circuit structure as shown in FIGS. 6 and 7, for example. Some are equipped with. In the structure shown in FIG. 6 and FIG. 7, 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 control valve 53 has a lower side 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 shown in FIGS. 6 and 7, when it is attempted to drive the working device while the right and left traveling devices are driven and the work device is traveling straight, the operating oil 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 the working oil is replenished to the working device while the vehicle is traveling straight as shown in FIGS. 6 and 7, 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 structures shown in FIG. 6 and FIG. 7, 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. The pair of pilot oil passages provided in each of the first and second pump systems and the first and second pilot oil passages. A pilot pump that supplies pilot pressure to both pilot oil passages of the two-pump system. [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 supply it to the control valve. [C] Both pilot oil passages are connected to respective portions between the control valve for the hydraulic traveling device and the control valve for the adjacent hydraulic actuator, and at least one of the pilot oil passages is provided. 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 one set value or more.

[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 and the machine body goes straight) (the 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 use in the vehicle are operated from the neutral position to the operating position. If such an operation is performed, the pilot oil passages 35, 36 are blocked at the positions of the control valves 13, 18 for the hydraulic traveling device, and the control valves 15, 19, 21 for the working device are placed at the positions. Also, the pilot oil passages 35 and 36 are shut off. As a result, the pilot pressure from the pilot pump 37 is applied to the pilot oil passage 3
5 and 36 cannot be passed through, pilot pressure above the set value is generated in the pilot oil passages 35 and 36, and this pilot pressure is supplied from the auxiliary pilot oil passage 38 to the switching valve 31 and the switching valve 31 is Switching operation is performed.
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 from the pilot pump 37 passes through both pilot oil passages 35 and 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 FIGS.
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 control valve of the center bypass type as described above, the control valves are installed in one block, and the spools are arranged side by side in parallel to each other and manufactured as one hydraulic unit. In many cases. Therefore, the pilot oil passage as in the present invention can be easily formed by drilling or the like that penetrates the block and each control valve.

[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. Further, 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.

[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 hydraulic motor (not shown) for the swivel base 2 (corresponding to another hydraulic actuator) is provided to the third pump 22 via oil passages 23, 24, 25 and 41. Control valve 26, fourth hydraulic cylinder 28 for swinging backhoe device 3 (corresponding to another hydraulic actuator)
5, a control valve 42 for the fifth hydraulic cylinder 40 (corresponding to another hydraulic actuator) for the dozer 27 of FIG. 5, and a switching valve 31 described later are connected in parallel. The control valves 26, 29, 42 and the switching valve 31 are of a center bypass type, and are pilot operated types which are switched by pilot pressure.

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, the oil passage 32 from the switching valve 31 on the third pump 22 side is replaced by 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. Switching valve 3
Reference numeral 1 is a pilot-operated type, as described above, which is switchable between a neutral position 31N that shuts off the oil passage 32 and a supply position 31A that supplies the hydraulic oil of the third pump 22 to the oil passage 32, and is internally installed. 31N neutral position by spring (not shown)
Biased to the 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 switching valve 31. Then, through the auxiliary pilot oil passage 38, both pilot oil passages 35, 36
A pilot pump 37 for supplying a pilot pressure is provided, and a pair of throttle portions 39 is provided between the pilot pump 37 and the auxiliary pilot oil passage 38.

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, the pilot pump Since the pilot pressure from 37 returns to the tank through both pilot oil passages 35 and 36,
The switching valve 31 is not switched from the neutral position 31N.

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.
1 to the actuated position, the control valves 15, 19, 21
Even if the pilot oil passages 35, 36 are cut off at the position of, the pilot pressure from the pilot pump 37 causes the control valves 13, 1 of the traveling device 1 in both the pilot oil passages 35, 36 to move.
The switching valve 31 of FIG. 2 is not switched from the neutral position 31N because it returns to the tank through the 8 side.

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 pilot pump 37 passes through the control valves 15, 19, 21 side of the backhoe device 3 in both pilot oil passages 35, 36. Since it returns to the tank, the switching valve 31 of FIG.
Is not switched from.

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 pilot pump 37 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 switching valve 31 and the switching valve 3
1 is switched from the neutral position 31N to the supply position 31A. Therefore, the hydraulic oil from the third pump 22 is transferred to the switching valve 31.
And the backhoe device 3 via the oil passages 32, 33, 34.
It is supplied to the control valves 15, 19, 21 for.

It should be noted that reference numerals are given in 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 on the first and second pump sides in a conventional structure.

FIG. 7 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 another 31 Switching valve 35, 36 Pilot oil passage 37 Pilot pump 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 valves (13), (1) for the hydraulic traveling device (1)
8) and respective control valves (15), (19), (21) for the hydraulic actuators (7), (8), (9), which are connected in series to each other for the hydraulic traveling device (1). Control valve (1
3), (18) and 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, and both pilot oil passages of the first and second pumps (10) and (16) systems A pilot pump (37) for supplying a pilot pressure to each of (35) and (36). [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). [C] In the pilot oil passages (35) and (36), the control valve (13) for the hydraulic traveling device (1),
(18) and the hydraulic actuators (8), (9) next to it
Which is connected to each of the portions between the control valves (15) and (19) for use with the pilot oil passages (35),
By the pilot pressure of at least one of the set values of (36), the switching valve (31) is operated by the hydraulic actuators (7) of the first and second pumps (10), (16).
Control valves (15), (19), (2) for (8), (9)
A pair of auxiliary pilot oil passages (38) that are switched to supply hydraulic oil to 1).