JPH062341A - Hydraulic circuit construction of operation car - Google Patents

Abstract

PURPOSE:To make it possible to adjust flow of operating fluid supplied to a service port so that it is applicable to a hydraulic device connected to the service port in construction of a hydraulic circuit of an operation car having a first manipulating means for normal operation changing discharge of variable capacity pumps for an operation device and controlling on the basis of load applied to the operation device. CONSTITUTION:Operating fluid from variable capacity pumps 10 and 17 is branched and joined to form so that it is supplied to service port 15, and second manipulating means 39 and 40 capable of setting and changing discharge of the pumps 10 and 17 in required flow are provided apart from a first manipulating means for normal work. According to the constitution, when the service port 15 is used, operation of the first manipulating means for normalwork is stopped, and the second manipulating means 39 and 40 for the service port 15 can be operated. On the contrary, in the case the use of the service port 15 is stopped, the first manipulating means is operated to stop the operation of the second manipulating means 39 and 40.

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 having a service port.

[0002]

2. Description of the Related Art In a backhoe which is an example of a work vehicle having a service port, for example, an actual Kaihei 2-1399 is used.
Some have a hydraulic circuit structure as disclosed in Japanese Patent Laid-Open No. 48. In this structure, a plurality of center bypass type control valves for the backhoe device (corresponding to a hydraulically driven working device) (38, 1 in FIG. 4 of the above publication) are used.
9) and the service port (2 in FIG. 4 of the publication).
0) for a center bypass type control valve (21 in FIG. 4 of the above publication) is connected in parallel to one pump (10 in FIG. 4 of the above publication) and another pump (the above publication) The oil passage from the center oil discharge passage of the 11) system in FIG. 4 (35 in FIG. 4 of the above publication) is connected to the center oil discharge passage in the above-mentioned pump and the control valve for the arm ( 1 in 4
9) and the control valve for the service port. As a result, the hydraulic oils from the two pumps merge and are supplied to the service port. In this way, a large amount of hydraulic oil is supplied to the service port so that even if a large-capacity hydraulic device is connected to the service port, the hydraulic oil can be supplied to this hydraulic device without a shortage.

[0003]

As described above, when the flow rate of the service port is set on the basis of the large capacity hydraulic device, a small flow rate of hydraulic oil is sufficient for a hand-held breaker, for example. If you connect the hydraulic system to the service port, the hydraulic oil will be excessively supplied to this hydraulic system,
This may lead to oil leakage, abnormal rise in oil temperature, shortening of the life of the hydraulic system, and the like. An object of the present invention is to make it possible to drive a large-capacity and small-capacity hydraulic device even if the hydraulic device is connected to a service port without trouble.

[0004]

In recent years, work vehicles having the following hydraulic circuit structure have appeared. That is, a plurality of variable displacement pumps that supply hydraulic oil to a hydraulically driven working device, a first actuator that changes the discharge amounts of the plurality of pumps in the same direction, and the load on the working device is detected. And a load detecting means for operating the work device so that the discharge amounts of the plurality of pumps decrease when the load applied to the work device increases, and the discharge amounts of the plurality of pumps increase when the load applied to the work device decreases. As described above, the first operating means for operating the first actuator is provided. The present invention relates to a hydraulic circuit structure of a work vehicle including a plurality of variable displacement pumps as described above and a first operating means for changing the discharge amounts of the plurality of pumps, as shown in the following [1]. It is characterized in that it is configured. [1] A second actuator configured to branch and merge hydraulic oils from a plurality of pumps and supply the service oil to a service port, and to increase and decrease the discharge amounts of the plurality of pumps in the same direction, and a second actuator. A second operation means for operating to a desired discharge amount position is provided, and the operation of the first operation means is stopped and the second operation means is operated in association with the operation of switching the service port to the use state, and the service port is operated. There is provided control means for operating the first operation means and stopping the operation of the second operation means in conjunction with the switching operation to the use stop state.

In addition to the work vehicle equipped with the plurality of pumps and the first operating means for the plurality of pumps as described above, there is one equipped with the following hydraulic circuit structure. That is, a variable displacement pump that supplies hydraulic oil to a hydraulically driven working device, a first actuator that changes the discharge amount of the pump, and a load detection unit that detects the load applied to the working device are provided. A first actuator is operated so that the discharge amount of the pump is decreased when the load applied to the work device is increased, and the discharge amount of the pump is increased when the load applied to the work device is decreased. It is provided with an operating means. The present invention provides a variable displacement pump as described above, and a first operation for changing the discharge amount of the pump.
The hydraulic circuit structure of the work vehicle provided with the operating means is characterized by being configured as shown in the following [2]. [2] A second actuator configured to branch the hydraulic oil from the pump to supply the service port to the service port, and a second operation for changing the discharge amount of the pump, and a second operation for operating the second actuator to a desired discharge amount position. With means,
The operation of the first operating means is stopped and the second operating means is operated in conjunction with the switching operation to the use state of the service port,
There is provided control means for operating the first operating means and stopping the operation of the second operating means in conjunction with the switching operation of the service port to the use stop state.

[0006]

[Action]

[I] With the configuration as described in [1] above, if the service port is stopped, the second operating means for the service port stops and the first operating means for normal work operates. As a result, when the load applied to the work device is increased, the discharge amounts of the plurality of pumps are decreased, and when the load applied to the work device is decreased, the discharge amounts of the plurality of pumps are operated to the increased side, and The discharge rate is adjusted according to the load applied to the work device and the output of the engine.

When the service port is used, the second operating means for the service port is activated and the first operating means for normal work is stopped. Thus, the second operation means and the second actuator can adjust the discharge amounts of the plurality of pumps, set the flow rate of the hydraulic oil suitable for the hydraulic device connected to the service port, and supply the hydraulic oil to this hydraulic device. it can. In this case, since the hydraulic oils of a plurality of pumps are combined and supplied to the service port, the flow rate of the hydraulic oil to the service port can be adjusted in a relatively large flow rate region. As a result, the configuration of the above [1] is suitable for connecting various hydraulic devices requiring a relatively large flow rate to the service port.

[II] If the configuration as in the preceding paragraph [2] is adopted, as in the case of the preceding paragraph [1], when the use of the service port is stopped, the second operating means for the service port is stopped and the normal operation work is performed. The first operation means of the. As a result, when the load applied to the work device increases, the discharge amount of the pump is decreased, and when the load applied to the work device decreases, the discharge amount of the pump increases, and the discharge amount of the pump changes to the work device. It is adjusted according to the applied load and engine output.

When the service port is used, the second operating means for the service port is activated and the first operating means for normal work is stopped. Accordingly, the discharge amount of the pump can be adjusted by the second operating means and the second actuator, and the flow rate of the hydraulic oil suitable for the hydraulic device connected to the service port can be set and supplied to this hydraulic device. In this case, since the hydraulic oil of one pump is supplied to the service port, the flow rate of the hydraulic oil to the service port can be adjusted in a relatively small flow rate region. As a result, the configuration of [2] above is suitable for connecting various hydraulic devices that require a relatively small flow rate to the service port.

[0010]

According to the present invention, since the flow rate of the hydraulic oil suitable for the hydraulic device connected to the service port can be set, the hydraulic oil is insufficient or the hydraulic oil is excessively supplied to the hydraulic device. It is possible to improve the workability of the work vehicle especially when the hydraulic device is connected to the service port without any trouble (due to malfunction of the hydraulic device, increase in oil temperature, etc.). In this case, since a plurality of variable displacement type pumps, which can be called existing structures, and their operating systems are effectively used, the configuration of claim 1 can be obtained only by equipping the second actuator for the service port and the like. This is also advantageous in terms of manufacturing cost. The configuration of claim 1 is effective especially when connecting a hydraulic device requiring a relatively large flow rate to the service port.

According to the second aspect, as in the first aspect, it is possible to set the flow rate of the hydraulic oil suitable for the hydraulic device connected to the service port. Particularly, the hydraulic device is installed in the service port. The workability of the work vehicle when connected can be improved. In this case, since the variable displacement pump, which can be called an existing structure, and its operating system are effectively used, the configuration according to claim 2 can be obtained only by equipping the second actuator for the service port. It is possible and advantageous in terms of manufacturing cost. The configuration of claim 2 is particularly effective when connecting a hydraulic device that requires a relatively small flow rate to the service port.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 2, a swivel base 2 is supported on the upper part of a pair of left and right crawler type traveling devices 1, and a backhoe device 3 (corresponding to a hydraulic drive type working device) is provided in front of the swivel base 2. A backhoe, which is an example of a work vehicle, is configured. The backhoe device 3 is composed of a boom 4 that is vertically swung by a hydraulic cylinder 7, an arm 5 that is swung back and forth by a hydraulic cylinder 8, and a bucket 6 that is swung and swung by a hydraulic cylinder 9. ing.
The entire backhoe device 3 is swingably supported around the vertical axis P1 at the front of the swivel base 2.

Next, the hydraulic circuit structure for the hydraulic cylinders 7, 8 and 9 will be described. As shown in FIG. 1, with respect to the oil passage 11 from the first pump 10, the left traveling device 1 is provided.
Control valve 12 for the hydraulic motor (not shown), auxiliary control valve 13 for the hydraulic cylinder 7 of the boom 4, control valve 14 for the hydraulic cylinder 8 of the arm 5, and control valve 16 for the service port 15 are parallel. It is connected to the. With respect to the oil passage 18 from the second pump 17, a control valve 19 for the hydraulic motor (not shown) of the right traveling device 1, a control valve 20 for the hydraulic cylinder 7 of the boom 4, and a hydraulic cylinder 9 of the bucket 6 are provided. The control valve 21 for is connected in parallel. And the third
A control valve (not shown) for the swivel base 2 and the like are connected in parallel to the oil passage 23 from the pump 22.

The control valves 12, 19, 16 for the traveling device 1 and the service port 15 are center bypass type and mechanically operated. Then, the control valve 1 for the backhoe device 3
4, 20, 21 and the auxiliary control valve 13 are center bypass type, three-position switching type pilot operated type. Figure 2
The operating portion 28 of the swivel base 2 shown in FIG. 2 is provided with a right operation lever 29 and a left operation lever 30 which can be operated in the front-rear direction and the left-right direction. A pilot valve (not shown) that generates a pilot pressure based on the pilot valve is provided, and as shown in FIG. 1, a pilot pump 24 that supplies the pilot pressure to the pilot valve is provided.

As a result, when the right operation lever 29 is operated back and forth, the control valve 20 for the boom 4 and the auxiliary control valve 13 are switched by the pilot pressure, and when operated right and left, the control valve 21 for the bucket 6 is operated by the pilot pressure. Is switched. In this case, when the boom 4 is raised, the hydraulic oils from the control valve 20 and the auxiliary control valve 13 merge and are supplied to the hydraulic cylinder 7 for the boom 4, and when the boom 4 is lowered, the hydraulic oil is supplied only from the control valve 20. It is supplied to the hydraulic cylinder 7. When the left operation lever 29 is operated back and forth, the pilot pressure switches the control valve 14 for the arm 5, and when it is operated left and right, the pilot pressure switches the control valve for the swivel base 2.

As shown in FIG. 1, an oil passage 26 is extended from the center oil discharge passage 25 of the second pump 17 system.
6 is the center oil drain passage 27 (arm 5
Between the control valve 14 for the boom and the auxiliary control valve 13 for the boom 4)
It is connected to the. Further, the oil passage 26 serves as a control valve 14 and 16 for the arm 5 and the service port 15 and a check valve 3.
It is connected between 1 and 1. With the above-described structure, the hydraulic oil in the center oil discharge passage 25 of the second pump 17 system merges with the hydraulic oil in the first pump 10, and is supplied to the control valve 14 for the arm 5 and the control valve 16 for the service port 15. Is being supplied.

Next, the first, second and third pumps 10, 17, 2
The structure for changing the discharge amount of No. 2 will be described. As shown in FIG. 1, the first, second and third pumps 10, 17, 22 are of variable displacement type, and a common operating member 32 is connected to the operating portion for changing the discharge amount. First,
The discharge amounts of the 2, 3 pumps 10, 17, 22 can be changed in the same direction. Then, a spring 33 for urging the operating member 32 toward the discharge amount increasing side and three sets of first operating cylinders 34 (corresponding to the first actuators) for pressing and pushing the operating member 32 toward the discharging amount decreasing side are provided. I have it.

Three sets of first pilot oil passages 35 (corresponding to load detecting means) for receiving pilot pressure from the oil passages 11, 18, 23 of the first, second, third pumps 10, 17, 22 are provided. Each of the three sets of pilot oil passages 35 is connected to the three sets of first operation cylinders 34 via a switching valve 36 (corresponding to control means). And service port 1
A switching lever 41 for switching the control valve 16 for 5 and the switching valve 36 is provided.

A pair of second operating cylinders 37 (corresponding to a second actuator) for pressing and pushing the operating member 32 on the side of reducing the discharge amount are provided, and a pair of first operating cylinders 37 for receiving pilot pressure from the pilot pump 24. 2 pilot oil passage 38
Is connected to the second operating cylinder 37 via the switching valve 36. A variable relief valve 39 (corresponding to a second operating means) capable of increasing / decreasing the pilot pressure is connected to the second pilot oil passage 38. The variable relief valve 39
An adjusting lever 40 (corresponding to a second operating means) for changing and adjusting the relief pressure of is provided.

The state shown in FIG. 1 is a state in which the switching lever 41 is operated to the use stop position of the service port 15. In this state, the control valve 16 for the service port 15 is operated to the neutral position, and the switching valve 36 moves the first pilot oil passage 3
5 is communicated with the first operation cylinder 34, and is operated to a position where the second pilot oil passage 38 is shut off. In this state, when the pressure of any one of the oil passages 11, 18, and 23 of the first, second, and third pumps 10, 17, and 22 becomes higher than a set value, the corresponding first operation cylinder 34
Is extended, and the first, second and third pumps 10, 17, 22 are operated to the side of decreasing the discharge amount. Conversely, three sets of oil passages 11, 1
When all the pressures of 8 and 23 become lower than the set value, the first, second and third pumps 10, 17, and 22 are operated by the action of the spring 33 to the side of increasing the discharge amount (the above is the first operation means. Equivalent). In this case, since the service port 15 is not used and the second pilot oil passage 38 is cut off, the second operation cylinder 37 does not operate (the first operation means is operated and the operation of the second operation means is stopped). Equivalent to the state to let).

On the contrary, the switching lever 41 is connected to the service port 15
Control valve 16 for the service port 15 is operated to the hydraulic oil supply position, the switching valve 36 shuts off the first pilot oil passage 35, and the second pilot oil passage 38 is operated second. It is operated to a position where it communicates with the cylinder 37. In this state, if the relief pressure of the variable relief valve 39 is adjusted by the adjusting lever 40, the second operating cylinder 37 overcomes the spring 33 and extends, or the spring 33 extends.
It can lose and contract. By changing the discharge amounts of the first, second, third pumps 10, 17, 22 in this manner, the hydraulic oil branched from the first and second pumps 10, 17 and joined to be supplied to the service port 15. The flow rate can be changed and adjusted to a desired flow rate. In this case, since the first pilot oil passages 35 are cut off, the first operation cylinders 34 do not operate.
(Corresponding to a state in which the operation of the first operating device is stopped and the second operating device is operated).

[Other Embodiment] In the embodiment shown in FIG. 1, the oil passage 2 is used.
6 is provided so that the hydraulic oil branched from the second pump 17 merges with the hydraulic oil on the first pump 10 side and is supplied to the service port 15. However, the oil passage 26 in FIG. As shown in FIG. 3 without providing the first pump 10
It may be configured to supply only the hydraulic oil from the service port 15 to the service port 15. In the case of the configuration of FIG. 3, the first, second, third pumps 10, 10
The discharge amounts of 17, 22 are changed in the same direction. Then, with the adjusting lever 40 and the variable relief valve 39,
The flow rate of the hydraulic oil supplied from the first pump 10 to the service port 15 can be adjusted. In the embodiment shown in FIG. 3, the discharge amounts of the first, second, third pumps 10, 17, 22 are not changed to the same direction, but the discharges of the first, second, third pumps 10, 17, 22 are discharged. The amount may be changed and adjusted independently.

In the embodiment shown in FIGS. 1 and 3, the pilot pressure from the pilot pump 24 is not supplied to the second operating cylinder 37, but the pilot pressure from the third pump 22 and the hydraulic oil to the service port 15 are used. The pilot pressure branching from may be supplied to the second operating cylinder 37. Further, in the embodiment shown in FIGS. 1 and 3, the stopper for stopping the contraction side (discharging amount increasing side) operation with respect to the second operation cylinder 37 at the set position is provided so that the first port is used when the service port 15 is used. , 2, 3 pumps 10, 17, 22 may not be operated to the maximum limit. In the embodiment shown in FIGS. 1 and 3, the hydraulic first and second operating cylinders 34 and 37 are used, but the first and second operating cylinders 34 and 37 are configured as electric cylinders, and The present invention may be configured so as to be electrically controlled.

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, second, third pump system and service port system.

[Fig. 2] Overall side view of the backhoe

FIG. 3 is a hydraulic circuit diagram of first, second, third pump system and service port system in another embodiment.

[Explanation of symbols]

 3 Working Device 10, 17 Pump 15 Service Port 34 First Actuator 35 Load Detection Means 36 Control Means 37 Second Actuator 39, 40 Second Operation Means

Claims (2)

[Claims] 1. A plurality of variable displacement pumps (10), (17) for supplying hydraulic oil to a hydraulically driven working device (3).
And a first actuator (34) for increasing / decreasing the discharge amount of the plurality of pumps (10), (17) in the same direction.
And a load detection means (35) for detecting a load applied to the working device (3), and when the load applied to the working device (3) increases, the plurality of pumps (10), (1)
The discharge amount of 7) is on the decreasing side, and when the load on the working device (3) is small, the discharge amounts of the plurality of pumps (10), (17) are on the increasing side. A hydraulic circuit structure for a work vehicle comprising a first operating means for operating a first actuator (34), wherein hydraulic oils from the plurality of pumps (10), (17) are branched and merged to form a service port. A second actuator (37) configured to supply to (15) and changing the discharge amount of the plurality of pumps (10) and (17) in the same direction, and the second actuator (37) are desired. Operation means (39), (40) for operating the discharge amount position of
And the operation of the first operating means is stopped to operate the second operating means (39), (40) in conjunction with the switching operation of the service port (15) to the use state, A control means (36) is provided which operates the first operation means and stops the operation of the second operation means (39), (40) in conjunction with the switching operation of the service port (15) to the use stop state. The hydraulic circuit structure of the working vehicle. 2. A variable displacement pump (10) for supplying hydraulic oil to a hydraulically driven working device (3), and a first actuator (34) for changing the discharge amount of this pump (10). A load detection means (35) for detecting a load applied to the working device (3), and the working device (3)
The discharge amount of the pump (10) is decreased when the load applied to the work device (3) is increased, and the discharge amount of the pump (10) is increased when the load applied to the working device (3) is decreased. And the first actuator (3
4) A hydraulic circuit structure for a working vehicle including a first operating means for activating 4), wherein the hydraulic oil from the pump (10) is branched and supplied to a service port (15). A second actuator (37) for changing the discharge amount of (10) and second operating means (39), (40) for operating the second actuator (37) to a desired discharge amount position.
And the operation of the first operating means is stopped to operate the second operating means (39), (40) in conjunction with the switching operation of the service port (15) to the use state, A control means (36) is provided which operates the first operation means and stops the operation of the second operation means (39), (40) in conjunction with the switching operation of the service port (15) to the use stop state. The hydraulic circuit structure of the working vehicle.