JPS6119604Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a work machine control device suitable for mounting a front loader on an agricultural tractor.

When installing a three-position selector valve for a front loader on an agricultural tractor, conventionally the space next to the handlebar post is used, making it difficult to operate the control lever due to its poor position, or piping getting in the way of other control levers. It also had the disadvantage of increasing costs.

In this invention, a three-position switching valve is directly attached to the cylinder head of the lift arm drive cylinder, so that the control lever knob can be placed in an easy-to-operate position such as the lower right of the cockpit seat. This is explained by:

Figure 1 is a partial view (right half) of the lift arm drive cylinder 1 seen from above with the cockpit seat removed. The right side of the tractor center line _O1 extending in the left-right direction is shown. The lift arm driving cylinder 1 is attached to the upper end surface of the transmission case, has a pair of lift arms 2 on the left and right, and has a side case 3 on the right side of the cylinder in front of the lift arms 2 (left side in the figure). . Two three-position switching valves 5, 5' and a return block 6 are attached to the right side of the cylinder head 4 on the side of a control lever 20 (to be described later) in front of the side case 3 using a plurality of bolts 7 in a skewered manner. One three-position switching valve 5 is connected to, for example, a hydraulic cylinder 8 (third position) for boom hoisting of a front loader.
The base end of the lever 10 is sandwiched between a pair of support brackets 9 provided on the upper end surface, connected with a pin 11, and the middle part of the lever 10 is connected to the spool 12. It is fitted into a slit on the upper end surface and connected with a pin 13. The lever 10 extends forward (to the left in the figure) from the spool 12 to the control lever 20 side of the cylinder head 4 and rises, and the knob 14 at the front end occupies an easy-to-grip position at the bottom right of the seat. When the knob 4 is pushed down, the spool 12 is lowered, and hydraulic pressure is supplied from the B port (described later) to the upper working chamber 15 of the hydraulic cylinder 8 (Fig. 3), and the lower working chamber 16 is connected to the drain tank circuit via the A port. Connect and hydraulic cylinder 8
When the knob 14 is pulled up, the switching valve 5 is switched, hydraulic pressure is supplied to the lower working chamber 16, and the upper working chamber 15 is connected to the tank circuit. The piston 17 is connected to the boom so that the piston 17 rises and the boom stands up. That is, when the knob 14 is pushed down, the boom is lowered, and when the knob 14 is pulled up, the boom is raised.

The other three-position switching valve 5' is for switching the hydraulic pressure to a hydraulic cylinder (not shown) for hoisting a shovel at the tip of the boom, and similarly has a lever 10', a spool 12', a knob 14', etc. The hydraulic pressure is changed so that when the knob 14' is pushed down, the shovel faces downward, and when the knob 14' is pulled up, the shovel stands up. The return block 6 has both switching valves 5,
It has a circuit (oil passage) for bypassing high pressure oil supplied from the pump to the switching valves 5 and 5' to the side case 3 side for driving the lift arm 2 when the switching valve 5' is in the neutral position. In FIG. 1, 18 is a control bracket, 19 is a control lever guide, and 20 is a control lever, and the control lever 20 is connected to a control valve (not shown) for controlling the lift arm.

FIG. 2 is a schematic front view of FIG. 1 when viewed in the direction of the arrow. The dashed line arrow indicates the hydraulic fluid flow path, and the hydraulic fluid pressurized by the pump flows through the inlet joint 22.
It is introduced into the cylinder head 4 through the oil passage 23 inside the cylinder head 4, and then through the oil passage 24 inside the three-position switching valves 5, 5', which will be described later, and the return block 6, and then through the oil passage 24 inside the return block 6. When 5 and 5' are in neutral, they reach the oil line 25 that connects to the control valve,
At least one of the switching valves 5, 5' is in operation, A,
Hydraulic pressure is supplied to one of the B ports or (and) one of the A' and B' ports, and the return oil from the corresponding cylinder is discharged to the tank circuit 26 from one of the ports. When both the switching valves 5, 5' are in the neutral state, the hydraulic fluid bypassing the switching valves 5, 5' and the return block 6 reaches the control valve circuit 25. 27 is a circuit that reaches the relief valve.

In FIG. 3 showing the hydraulic circuit, 28 is a pump, 29 is a relief valve, 30 is a bypass circuit, 3
1 is a tank circuit, and 32 is a tank. Switching valve 5
The A port of is connected to the lower working chamber 16 via the circuit 33,
Further, the B ports are respectively connected to the upper working chamber 15 via circuits 34. When the switching valves 5, 5' are in the neutral state shown in the figure, the bypass circuits 30, 30' in the switching valves 5, 5' are in communication, and the P port is connected to the control valve via the circuit 25. Therefore, the third
As shown in the figure, when both switching valves 5 and 5' are in neutral, pump 2
The hydraulic oil pressurized in step 8 reaches the control valve via bypass circuits 30, 30' in both switching valves 5, 5' and circuit 25, and is used as the machine hydraulic pressure.
Next, when the switching valve 5 is switched in the direction of arrow D (downward direction), the bypass circuits 30 and 30' are cut off, the P' port connected to the pump is connected to the B port, and the A port is connected to the tank circuit 31. It is connected to the tank 32, and the piston 17 and the boom of the front loader are lowered as described above. When the switching valve 5 is switched in the direction of arrow U (lifting direction), the P' port is connected to the A port and hydraulic pressure is supplied to the lower working chamber 16, and the upper working chamber 15 is connected to the tank circuit 31 from the B port, and the piston 17 goes up. Port of switching valve 5'
Since A' and B' are connected to a cylinder for hoisting the shovel (not shown), the cylinder for hoisting the shovel is operated by operating the switching valve 5'.

The - cross section of Figures 1 and 2 is shown in Figure 4, and
A - cross section of the figure is shown in FIG. In FIG. 4, the main body 35 of the switching valve 5 has a cylinder surface 36, into which the spool 12 is slidably fitted. The spool 12 includes a vertical hole 37 extending in the longitudinal direction and horizontal holes 38 and 39 perpendicular to the vertical hole 37, and a stepped plug 40 is screwed into the lower end of the vertical hole 37 to close the lower end of the vertical hole 37. . The large-diameter cylindrical portion of the plug 40 includes
A pair of spring receivers 42 and 43 are slidably fitted between the lower end surface of the spool 12 and the snap spring 41, and a coil spring 44 is compressed between the spring receivers 42 and 43. A stepped portion 45 is provided at the lower end of the cylinder surface 36.
A cap 47 is screwed into a screw hole 46 provided through the cap, and a shim 48 is sandwiched between the stepped portion 45 and the cap 47, and both spring receivers 42 are attached to the inner bottom surface of the cap 47.
The thickness of the shim 48 is determined so that the shim 43 is in contact with the shim 48.
49 is a breather hole. The spool 12 is normally held at the neutral position shown in the figure by the action of the spring supports 42, 43 and the spring 44.

The cylinder surface 36 is provided with annular grooves 51 to 56, with the annular groove 51 connected to the A port, the annular groove 53 connected to the B port, and the annular groove 54 connected to the tank circuit 31 provided in the main body 35. The spool 12 has an annular groove 57
-60, the annular groove 57 is connected to the lateral groove 38, and the annular groove 59 is connected to the lateral groove 39, respectively. Fifth
As is clear from the figure, the annular groove 52 is connected to the inclined ports P ₁ and P ₂ in the main body 35, the annular groove 55 is connected to the port P ₃ , and the annular groove 56 is connected to the port P ₄ . ing. Ports P ₂ and P ₃ are return block 6
The two bypass circuits 24 communicate with each other. Port P ₁ is connected to port P' ₂ of switching valve 5', and port P ₄ is connected to port P' ₃ of switching valve 5'. In addition, 61 in Figure 4,
62 is an O-ring.

In the neutral state shown in FIGS. 4 and 5, the groove 60 is the groove 5.
5 and 56 are connected, ports P ₁ to P ₄ and grooves 52, 55, 56, and 60 in the switching valve 5 form a bypass circuit that bypasses high-pressure oil from the pump to the machine side. , the grooves 51 and 53 communicating with ports A and B are blocked by the spool 12, so the hydraulic cylinder 8 (third) of the front loader
is in a locked state. When the spool 12 is pushed in the D direction, the grooves 55 and 60 are blocked, and the groove 52 communicating with the port P ₁ is connected to the port B via the grooves 58 and 53, and hydraulic pressure is supplied to the upper working chamber 15 of the hydraulic cylinder 8. be done. Port A, which communicates with the lower working chamber 16, communicates with the tank circuit 31 through grooves 51, 57 and holes 38, 37, 39. This lowers the front loader boom. When the spool 12 is pulled up in the U direction, the groove 52 communicating with the port P ₁ becomes the groove 5.
8 and 51 to port A, and hydraulic pressure is supplied to the lower working chamber 16 of the hydraulic cylinder 8. At that time, the port B communicating with the upper working chamber 15 has grooves 53 and 5.
9, it communicates with the tank circuit 31 through the hole 39, which causes the boom to rise.

In the agricultural tractor work machine control device of the present invention,
A plurality of three-position switching valves 5, 5' dedicated to operating external work equipment other than for driving the lift arm and a return block 6 are connected to the head 4 of the cylinder 1 for driving the lift arm.
At the same time, the three-position switching valve 5,
5' control levers 10, 10' to the cylinder head 4.
The lift arm drive cylinder 1 is installed on the control lever 20 side and stands up near the cockpit seat above the lift arm drive cylinder 1.
is operated by a control lever 20, and the plurality of three-position switching valves 5, 5' dedicated to operating external work equipment other than for driving the lift arm are operated by a separate control lever 1.
0 and 10', and during work, simply select which lever to operate and grasp that lever to operate the desired external work equipment, allowing work to be done quickly and reliably, while also improving skill. Not needed.

Also, since multiple switching valves 5, 5'... can be installed,
Multiple hydraulic cylinders of external work equipment can be operated freely, making complex work easier.

Moreover, a plurality of three-position switching valves 5, 5' dedicated for operating external work equipment are connected to the lift arm drive cylinder 1.
The driver's seat seat above the cylinder for driving the lift arm is directly attached to the control lever 20 side of the cylinder head 4 in a skewered manner, and the control levers 10 and 10' of the three-position switching valve are provided on the control lever 20 side of the cylinder head 4. Since the levers 10, 10' are erected close to each other, the levers 10, 10' can be disposed in the shortest distance at the lower right position of the seat where they can be easily grasped, and the levers 10, 10' can be made short and lightweight. Therefore, vibration of the levers 10, 10' can be prevented, and the levers 10, 10' can be operated easily and more reliably.
Further, according to the present invention, since no piping is required, it is possible to achieve a significant cost reduction, and it can be installed in a narrow space, so that it does not get in the way of other operating levers.

[Brief explanation of the drawing]

Figure 1 is the right half of the plan view of the agricultural tractor with the driver's seat removed, and Figure 2 is the same figure as shown in Figure 1.
Front view as seen from the arrows, Figure 3 is a hydraulic circuit diagram, Figure 4 is a hydraulic circuit diagram, and Figure 4 is a hydraulic circuit diagram.
2, and FIG. 5 is a cross-sectional view of FIG. 4. 5, 5'...Three-position switching valve, 8...Hydraulic cylinder, 15, 16...Working chamber, 28...Pump, 3
0... Bypass circuit, 31... Tank circuit, 35
... Valve body, 37 ... Vertical hole (return circuit), 39 ...
Side hole (return circuit).

Claims (1)

[Scope of utility model registration request] A plurality of three-position switching valves 5, 5' dedicated to operating external work equipment other than for driving the lift arm are connected to a return block 6 by a plurality of bolts to the control lever 20 side of the head 4 of the cylinder 1 for driving the lift arm. The control levers 10, 10' of the three-position switching valves 5, 5' are installed on the control lever 20 side of the cylinder head 4, and are erected near the cockpit seat above the cylinder for driving the lift arm. A work machine control device for an agricultural tractor, which is characterized by: