JP2775060B2 - Hydraulic equipment for work vehicles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydraulic device for a working vehicle such as an agricultural tractor.

[Problems to be Solved by the Prior Art and the Invention] In general, among hydraulic devices provided in this kind of working vehicle, a plurality of hydraulic oils supplied from a hydraulic pump through a corresponding shunt valve mechanism are supplied to the hydraulic oil. Some actuators are supplied to each actuator.

Conventionally, however, since the supply amount of hydraulic oil supplied to the hydraulic actuator from the corresponding flow dividing valve mechanism is set to a constant amount necessary for the hydraulic actuator to operate smoothly, the working unit is required when traveling on a road. There is waste in the supply of pressurized oil, such as the supply of excess pressure oil to the control system actuator or the supply of excess pressure oil to the travel system actuator during field work. In this case, a large hydraulic pump having a large discharge rate must be used.

In addition, when the engine speed is low and the pressure oil supply amount is small, the pressure oil is preferentially supplied to the hydraulic actuator that is diverted on the upstream side of the flow path and supplied with hydraulic pressure,
There is also a problem that the smooth operation is impaired because the supply of the pressure oil to the hydraulic actuator on the lower side of the flow path is reduced.

[Means for Solving the Problems] The present invention has been made with the object of providing a hydraulic device for a working vehicle that can eliminate these disadvantages in view of the above-described circumstances, In the first invention, a first branch valve mechanism is provided in an oil path to which the pressure oil is supplied, and a first flow path in which a predetermined flow rate of the pressure oil is preferentially supplied to the first main flow path and the first surplus oil flow path. Divided, the first surplus oil flow path, a second flow dividing valve mechanism is provided to divide the flow into a second main flow path and a second surplus oil flow path in which a predetermined amount of pressure oil is supplied preferentially. In order to supply pressure oil to the corresponding first, second, and third hydraulic actuators, the third hydraulic pressure is supplied to a flow path between the second excess oil flow path and the third hydraulic actuator. The actuator is provided with a third diverting valve mechanism that is set to preferentially supply a predetermined amount of pressure oil, and a third excess The oil flow path is branched and the third excess oil flow path is connected to the first and second main oil paths via supply destination switching means for selectively switching the excess oil supply destination. Things.

Further, the second invention provides a first main flow path and a first surplus oil flow path in which an oil passage to which the pressure oil is supplied is provided with a first branch valve mechanism and a predetermined flow rate of the pressure oil is supplied preferentially. The first excess oil flow path is divided into a second main flow path and a second excess oil flow path in which a predetermined flow rate of the pressure oil is supplied preferentially by providing a second branch valve mechanism in the first excess oil flow path. In order to supply pressure oil to the first, second, and third hydraulic actuators respectively corresponding to the third excess hydraulic flow path and the third hydraulic actuator, The hydraulic actuator is provided with a third branch valve mechanism that is set to supply a predetermined amount of pressure oil preferentially to branch and form a third surplus oil flow path. The oil supply destination is connected to the first and second main oil passages via supply destination switching means for selectively switching the oil supply destination, and the supply destination switching means is supplied with surplus oil. It is characterized in that the tandem supply switching control means for outputting a switching operation command to the supply destination switching means to determine.

Further, in these inventions, the first and second hydraulic actuators are an actuator for steering and an actuator for horizontal control of the working unit, and the third hydraulic actuator is an actuator for lifting and lowering the working unit.

The present invention is intended to eliminate the useless supply of pressurized oil and to enable the use of a small hydraulic pump.

Example Next, an example of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 denotes a traveling body of an agricultural tractor, and a rotary tilling type working unit 3 is connected to a rear portion of the traveling body 1 via an elevating link mechanism 2, and the working unit 3 is a hydraulic cylinder. The lift arm 5 is moved up and down by swinging of the lift arm 5 in accordance with the expansion and contraction operation of the lift arm 4, and is inclined left and right by the expansion and contraction operation of a rod cylinder 7 connecting the lift arm 5 and the lower link 6. In addition, 9 is a steering wheel.

On the other hand, reference numeral 10 denotes a hydraulic pump, and the hydraulic oil pumped by the hydraulic pump 10 first passes through the first main flow path A1 in the first branch valve A.
And a first surplus oil flow path A2, and a predetermined small flow rate is supplied to the power steering mechanism 11 in the first main flow path A1.
The excess oil is supplied preferentially to the hydraulic cylinder 4 and the rod cylinder 7 via the high-speed circulating mechanism 12 and the relief valve mechanism 13. It is supplied to a control valve mechanism 14 for operation. In the control valve mechanism 14, the supplied pressure oil is divided into the second main flow path B1 and the second surplus oil flow path B2 by the second flow dividing valve B, but is set to be small in the second main flow path B1. A predetermined flow rate is preferentially supplied to the operating mechanism 16 on the rod cylinder 7 side, and the surplus oil is supplied to the second surplus oil passage B2 and supplied to the operating mechanism 15 side of the hydraulic cylinder 4. I have. The operating mechanism 16 on the rod cylinder 7 side and the operating mechanism 15 on the hydraulic cylinder 4 side to which the pressurized oil is supplied respectively include an electromagnetic switching valve 17,
By the operation of 18, pressure oil is supplied to the rod cylinder 7 and the hydraulic cylinder 4 to make them expand and contract.

Further, C is a third branch valve provided in the control valve mechanism 14, and the third branch valve C is provided in an oil passage before reaching the operating mechanism 15 of the second excess oil flow path B2. ,
The third main flow path C1 has an operating mechanism 15 on the hydraulic cylinder 4 side.
A smaller amount of pressure oil is preferentially supplied to the third excess oil passage C2, and the excess oil is selectively supplied to the operating mechanism 16 on the rod cylinder 7 side or the power steering mechanism 11 side. To be joined. That is,
An electromagnetic switching valve 19 is provided in the third excess oil flow path C2 of the third branch valve C, and each output port of the electromagnetic switching valve 19 is connected to the operating mechanism 16 and the power steering mechanism 11 on the rod cylinder 7 side, respectively. It is connected. And the electromagnetic switching valve 19
The switching destination of the surplus oil is switched in accordance with the operation of the solenoid according to the operation command from the control circuit 20, which will be described later. However, when the solenoid is turned off, the elastic oil is always supplied to supply the surplus oil to the power steering mechanism 11 side. The configuration is biased by the

The control circuit 20 is configured as a relay sequence circuit formed by parallel circuits of addresses 1 to 4, and an arm angle sensor 21 for detecting the swing angle of the lift arm 5 is provided at the first address. At address 2, a transistor Tr and a relay R1 whose base terminals are connected to the arm angle sensor 21 are provided.
Are provided in series, and the third address is a PTO shift lever 2
2, a lever position detection switch 23 for detecting the lever position and a relay R2 are provided in series. Further, at a fourth address, a break contact of the relay R1, a make contact of the relay R2, and a solenoid of the electromagnetic switching valve 19 are provided. And are connected in series. That is, the control circuit 20 determines that the lift arm angle is equal to or smaller than the predetermined angle (the working unit 3 is in the lowered state) and the PTO speed change lever 22
When the solenoid is operated to the PTO operating position, the electromagnetic switching valve 19 is switched to the rod cylinder 7 side by closing both contacts of the relays R1 and R2, but the lift arm angle is larger than a predetermined angle. When this happens, the break contact of the relay R1 is opened by energizing the transistor Tr in accordance with the signal output of the arm angle sensor 21, and the contact of the relay R2 is opened even when the PTO speed change lever 22 is set to the stop position, so that the solenoid is opened. Is turned off, and the electromagnetic switching valve 19 is returned to the power steering mechanism 11 side.

In the embodiment of the present invention configured as described above, when the control circuit 20 determines that ground work is being performed based on the lift arm angle and the PTO shift state, the surplus oil is joined to the operating mechanism 16 on the rod cylinder 7 side. When the operation speed of the rod cylinder 7 is ensured, and when it is determined that the work is not performed on the ground, the surplus oil is merged with the power steering mechanism 11 to ensure the following performance and the light operability of the power steering mechanism 11. Will do.

As described above, in the embodiment in which the present invention is implemented, the pressure oil pumped by the hydraulic pump 10 is supplied to the first to third flow dividing valve mechanisms A,
Hydraulic actuators 11, 7, corresponding to B and C respectively
4, the amount of pressurized oil supplied to the rod cylinder 7 and the power steering mechanism 11 is limited to a small amount in advance, and excess oil surplus in the supply of the pressurized oil is selectively supplied to the rod cylinder 7 or the power steering mechanism 11. Because it is configured to supply to
By appropriately switching the supply destination of the surplus oil, for example, a required amount of pressure oil is supplied to the rod cylinder 7 which is an actuator of the working unit control system at the time of ground work, and a power steering which is an actuator of the travel control system at the time of non-ground work. The required amount of pressure oil is supplied to the mechanism 11. Therefore, at the time of ground work and non-ground work, only a predetermined small amount of pressurized oil is supplied to the power steering mechanism 11 and the rod cylinder 7, respectively. Pressure oil supply can be eliminated to reduce the total pressure oil supply,
As a result, it is possible to use a small hydraulic pump having a small discharge amount.

Moreover, the switching of the surplus oil supply destination is automatically performed based on the judgment of the control circuit 20, so that the efficient supply of the pressure oil can be performed without complicating the operation.

In addition, since the electromagnetic switching valve 19 that switches the supply destination of surplus oil is constantly urged to the power steering supply side by the ammunition, even if a failure occurs in the temporary control circuit 20 etc., the followability of the power steering is guaranteed. Safety can be ensured.

The present invention is, of course, not limited to the above-described embodiment. Needless to say, the present invention can be carried out in a combine or the like in addition to the agricultural tractor of the above-described embodiment. However, one of the supply destinations may be a pressure oil tank. As a control circuit for the electromagnetic switching valve, as in the second embodiment shown in FIG. 4, a horizontal sensor 24 for detecting body inclination and a rotation sensor 25 for detecting axle rotation are provided. During horizontal control, surplus oil is supplied to the rod cylinder side, and at other times, surplus oil is supplied to the power steering side, and even during high-speed driving, excess oil is supplied to the rod cylinder side with priority. May be. That is, according to this embodiment, an accident due to excessive turning of the steering wheel can be prevented by reducing the followability of the power steering during high-speed running.

[Effects] In summary, since the present invention is configured as described above, the hydraulic oil pumped by the hydraulic pump is supplied to the plurality of hydraulic actuators via the corresponding flow dividing valve mechanism. By setting the amount of hydraulic oil supplied from the shunt valve mechanism to the first and second hydraulic actuators to be relatively small, the engine speed is low and the hydraulic oil supply from the hydraulic pump is small. However, the amount of pressure oil supplied from the third shunt valve mechanism to the third hydraulic actuator can be ensured, so that the third hydraulic actuator can be operated smoothly.

Then, the pressure oil supply amounts to the first and second hydraulic actuators set to be small are selectively supplied from the third excess oil flow path branched from the third branch valve mechanism and supplemented. Therefore, it is possible to supply the pressure oil without waste corresponding to the working state, and as a result, it is possible to reduce the supply amount of the pressure oil in the entire hydraulic device, and it is also possible to operate the actuator with a small hydraulic pump having a small discharge amount. .

Further, in the case where the supply switching control means for determining the supply destination of the surplus oil and outputting the switching operation command to the supply destination switching means is connected to the supply destination switching means, the operator does not perform any switching operation, The operability can be improved by efficiently and efficiently switching the supply of pressure oil to the first and second hydraulic actuators according to the work situation.

When the third hydraulic actuator is an actuator for raising / lowering the working unit, the lifting / lowering operation of the working unit, which requires particularly smooth hydraulic operation as a working vehicle, is performed when the engine is running at a low speed, that is, the hydraulic oil from the hydraulic pump. Even when the supply amount is small, it is possible to preferentially supply the pressurized oil to the lifting actuator to ensure smooth lifting and lowering of the working unit.

[Brief description of the drawings]

The drawings show an embodiment of a hydraulic device for a working vehicle according to the present invention. FIG. 1 is an overall side view of an agricultural tractor, FIG. 2 is a hydraulic circuit diagram, and FIG. 3 is a control circuit. FIG. 4 is a circuit diagram of a control circuit showing a second embodiment. In the figure, 1 is a traveling body, 3 is a working unit, 4 is a hydraulic cylinder,
7 is a rod cylinder, 10 is a hydraulic pump, 11 is a power steering mechanism, 19 is an electromagnetic switching valve, 20 is a control circuit, A,
B and C are flow dividing valves.

Claims (3)

(57) [Claims] A first main flow path and a first surplus oil flow path in which a predetermined flow rate of pressure oil is supplied preferentially by providing a first flow dividing valve mechanism (A) in an oil path to which pressure oil is supplied. A second main flow path and a second surplus oil flow path in which a second flow dividing valve mechanism (B) is provided in the first surplus oil flow path and pressure oil of a predetermined flow rate is supplied preferentially. In configuring to supply pressure oil to the corresponding first, second, and third hydraulic actuators, respectively, in the flow path between the second excess oil flow path and the third hydraulic actuator, The third hydraulic actuator is provided with a third branch valve mechanism (C) that is set to supply a predetermined flow rate of pressure oil preferentially to branch and form a third excess oil flow path. A work run characterized in that the surplus oil passage is connected to the first and second main oil passages via supply destination switching means (19) for selectively switching the surplus oil supply destination. Car of the hydraulic system. 2. A first main flow path and a first surplus oil flow path in which a predetermined flow rate of pressure oil is supplied preferentially by providing a first branch valve mechanism (A) in an oil path to which pressure oil is supplied. A second main flow path and a second surplus oil flow path in which a second flow dividing valve mechanism (B) is provided in the first surplus oil flow path and pressure oil of a predetermined flow rate is supplied preferentially. In configuring to supply pressure oil to the corresponding first, second, and third hydraulic actuators, respectively, in the flow path between the second excess oil flow path and the third hydraulic actuator, The third hydraulic actuator is provided with a third branch valve mechanism (C) that is set to supply a predetermined flow rate of pressure oil preferentially to branch and form a third excess oil flow path. The surplus oil flow path is connected to the first and second main oil passages via supply destination switching means (19) for selectively switching the surplus oil supply destination. Is working vehicle hydraulic apparatus being characterized in that tandem supply switching control means for outputting a switching operation command to the supply destination switching means to determine the destination of the excess oil. 3. The steering actuator according to claim 1, wherein the first and second hydraulic actuators are steering actuators.
And a working unit horizontal control actuator (7), wherein the third hydraulic actuator is a working unit lifting / lowering actuator (4).