JPS646642Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to work vehicles such as tractors and bulldozers, and is characterized in that it improves the safety of operation of working machines such as rotaries.

The tractor is provided with a working machine lifting device at the rear of the body, and a working machine such as a rotary is attached to the rear end of the working machine lifting device. This rotary is connected to a PTO shaft provided at the rear of the machine, and is driven to rotate by the rotation of the PTO shaft, and can be driven up and down by operating the work equipment lifting device. By the way, when the machine is moving forward to perform plowing work, the rotary is lowered and driven to rotate, but when the machine is running forward or backward without plowing, the rotary is raised and the rotary is at the upper limit position. When this is reached, a sensor detects this and automatically stops the rotational drive of the rotary. However, if the rotary is lowered even slightly from the upper limit position, the rotary is immediately driven to rotate. On the other hand, a mechanism has been proposed in which the rotation of the rotary is automatically stopped when the driver leaves the seat, but the rotary is supposed to start rotating immediately when the driver takes the seat again. However, there was a lot of wasted power, and there was a risk of injury to workers near the rotary.

The present invention was developed in view of this problem, and if the rotary or other work equipment stops rotating due to the driver leaving the seat, it will immediately stop rotating when the driver re-seats. By preventing the drive from being driven, safety during operation of the work equipment is further improved. The present invention will be described in detail below with reference to drawings showing embodiments thereof.

Figure 1 is a partially exploded left side view of a tractor consisting of front wheels 1, rear wheels 2, driver's seat 3, steering handle 4, etc. At the rear of the machine, there are lower links 5, top links 6, and lift arms 7. A working machine 8 such as a rotary is swingably connected to the lower link 5 and the top link 6. The lift arm 7 is hydraulically driven by a hydraulic cylinder 9, and its rear end portion is driven in the vertical direction so that the work implement 8 can be moved up and down.
Further, a PTO shaft 10 is protruded from the rear of the machine, and the PTO shaft 10 and the working machine 8 are connected by a connecting shaft 11, so that the working machine 8 is rotationally driven by rotating the PTO shaft 10. It's summery. A first sensor 12 is provided at the rear of the driver's seat 3 and includes a limit switch or the like that comes into contact with the lift arm 7 when it reaches its upper limit position to detect that the lift arm 7 is at its upper limit position. Further, a second sensor 13 consisting of a limit switch, a pressure sensitive element, etc. is disposed in the driver's seat 3 to detect when the driver is away from the seat.

FIG. 2 is a circuit diagram showing both the electric system and the hydraulic system of the tractor according to the present invention, in which 14 is a battery, 15 is a key switch that turns on and off power to the electric circuit, and M ₂ a is an auxiliary relay M _{2 M1a} is a normally open contact of the auxiliary relay _M1 , 12a is a normally open contact of the first sensor 12, and 16 is an automatically reset normally closed type consisting of a manually operated push button switch, etc. This is the reset switch. Ta is timer T
13b is a normally closed contact of the second sensor 13, _M1b is a normally closed contact of the auxiliary relay _M1 ,
Reference numeral 17 denotes a changeover switch for manually selecting the rotation speed of the PTO shaft 10 between 1st speed and 2nd speed. 1
8 is a 5-port 3-position switching type electromagnetic control valve having solenoids 18s and 18, 19 is a relief valve,
20 is an oil tank, 21 and 22 are the 1st and 2nd speeds of the power shift transmission that drives the PTO shaft 10;
The hydraulic multi-disc clutch _P1 is a hydraulic pump that supplies pressure oil to the hydraulic multi-disc clutches 21 and 22. 23 is a 3-port 3-position switching type manual control valve having a manual operation lever 23a, 24 is a relief valve, 25 is an oil tank, and P ₂ is a hydraulic pump that supplies pressure oil to the hydraulic cylinder 9. These hydraulic pumps P ₁ and P ₂ are rotationally driven in conjunction with the engine E.

The negative electrode of the battery 14 is body grounded to the fuselage, and both ends of the series circuit consisting of the normally open contact 12a, the reset switch 16, and the relay coil _M1C of the auxiliary relay _M1 are connected to the positive electrode of the battery 14 via the key switch 15. , connected to the negative electrode. Further, normally open contacts M ₁ a and M ₂ a are connected in parallel to the normally open contact 12a. Normally closed contact 13 is connected to the series circuit of normally _open contact Ta and relay coil _M2C of auxiliary relay M2.
A series circuit of the clock section TC of the timer T and the clock section TC of the timer T are connected in parallel, and both ends of these series circuits are connected to the positive and negative electrodes of the battery 14 via the key switch 15. Solenoid 18 of electromagnetic control valve 18
One end of s, 18 is grounded to the body of the aircraft, and the other end is connected to selection switch 17 and normally closed contact M ₁ b
It is also connected to the positive electrode of the battery 14 via the key switch 15. The solenoid 18s is energized when the movable contact 17a of the selection switch 17 is switched to the fixed contact 17b side, and the solenoid 18 is energized when the movable contact 17a of the selection switch 17 is switched to the fixed contact 17c side.

On the other hand, in the hydraulic drive circuit, the solenoid 18
Both s and 18 are not excited and the hydraulic pump
When P ₁ is driven, the supplied pressure oil returns to the oil tank 20 through the solenoid control valve 18, and when the solenoid 18s is energized, the supplied pressure oil returns to the oil tank 20 through the solenoid control valve 18.
8 moves in the direction of the arrow and switches to the S side, and pressure oil is supplied to the first speed multi-disc clutch 21 and the PTO shaft 10
When the solenoid 18 is energized, it is switched to the opposite side of the arrow, and pressure oil is supplied to the 2nd speed multi-disc clutch 22, and the PTO shaft 1 is rotated at a low speed.
0 can be rotated at high speed. Further, when the hydraulic pump P ₂ is being driven and the operating lever 23a is in the neutral state, the pressure oil from the hydraulic pump P ₂ is returned to the oil tank 25 via the manual control valve 23, and the operating lever 23a is operated to control the pressure oil. When switching to the direction indicated, that is, to the U side, pressure oil flows to the manual control valve 23.
The piston rod 9 is extended and the lift arm 7 is raised. On the other hand, when the operating lever 23a is operated to switch to the D side, the oil in the hydraulic cylinder 9 and the pressure oil being fed are returned to the oil tank 25, and the lift arm 7 is lowered by the weight of the work equipment 8, etc. that is applied to the piston rod 9a. is configured to do so.

Next, the operation of the tractor with improved operating safety of the working machine according to the present invention will be explained with reference to FIGS. 1 and 2. Prior to driving the tractor, the time limit of the timer T is set to at least the time required for the driver to temporarily lift his hips above the driver's seat 3 on the machine body and sit down again, for example, about 1 minute. Thereafter, the driver takes a seat in the driver's seat 3 and turns on the key switch 15 to start the engine E and drive the hydraulic pumps P ₁ and P ₂ . Since the driver is seated in the driver's seat 3, the normally closed contact 13b of the second sensor 13 provided in the driver's seat 3 is open, and even when the key switch 15 is closed, the timer T is closed.
The timer T is not energized and the timer T does not perform timekeeping operation. Also, normally open contacts M ₂ a, 12 a, M ₁ a
Due to the open circuit, the relay coil M ₁ c of the auxiliary relay M ₁ is also not energized. Therefore, when performing plowing work by moving the machine forward and rotating the work implement 8, first drive the operating lever 23a of the manual control valve 23 in the direction opposite to the arrow to switch it to the D side, and then turn the hydraulic pump P on. ₂ and the oil in the hydraulic cylinder 9 is returned to the oil tank 25. As a result, the piston rod 9a retracts, lowering the lift arm 7 and lowering the work implement 8.
Then, by selectively closing the movable contact 17a of the selection switch 17 to the fixed contact 17b (or 17c) side, the solenoid 18s (or 18) of the electromagnetic control valve 18 is energized, in the direction of the arrow, that is, s (or).
switch to the side. By switching the electromagnetic control valve 18, the pressure oil of the hydraulic pump _P1 is fed to the first speed (or second speed) multi-disc clutch 21 (or 22), and the PTO
The shaft 10 is rotationally driven, and the working machine 8 is rotated at a low (or high) speed, so that plowing work can be performed as the machine moves.

When the work implement 8 is to be raised to rotate or retreat the machine after completing a predetermined plowing operation, the operating lever 23a of the manual control valve 23 is manually operated to switch to the direction of the arrow, that is, to the U side. . As a result, the hydraulic pressure from the hydraulic pump _P2 is supplied to the hydraulic cylinder 9 to raise the lift arm 7, thereby raising the work implement 8 while rotating. In this way, the work machine 8
When the lift arm 7 is raised to the upper limit position, the lift arm 7 contacts the first sensor 12 and closes its normally open contact 12a. The relay coil _M1c of the auxiliary relay _M1 is energized by the closing of the normally open contact 12a, the normally open contact _M1a is closed and the auxiliary relay _M1 is self-held, and at the same time the normally closed contact _M1b is opened. The solenoid 18s (or 18) is deenergized, the solenoid control valve 18 is switched to the neutral position, and the 1st (or 2nd) speed is set.
The supply of pressure oil to the multi-disc clutch 21 (or 22) of the PTO shaft 10 stops, and the rotation of the PTO shaft 10 stops.
The rotation of the working machine 8 can be stopped. When the machine completes turning or reversing and wants to perform the tilling work again, the operation lever 23a is operated in the same manner as described above to lower the work machine 8, but the auxiliary relay _M1 remains self-held. If the normally closed contact M ₁ b remains open and the work equipment 8 is unintentionally lowered from the upper limit position, the PTO shaft 10 and the work equipment 8 will not rotate at all, ensuring safe operation of the work equipment 8. It is being After confirming that the work equipment 8 has descended sufficiently and can be rotated without danger, the self-holding of the auxiliary relay _M1 is released by manually operating the reset switch 16 and opening the normally open contact.
M ₁ b is closed, and the PTO shaft 10 is driven to rotate in the same manner as described above to rotate the work implement 8 and the tilling operation can be resumed.

Next, during the tilling work, if an emergency occurs and the driver stops the machine and leaves the driver's seat 3, the normally closed contact 1 of the second sensor 13
3b is closed, the timer TC of the timer T is energized, and the timer T starts its timekeeping operation. Therefore, if the driver is not yet seated in the driver's seat 3 at the end of the timing operation, the normally open contact Ta is closed and the auxiliary relay is activated.
Excite the M ₂ relay coil M ₂ c. The normally open contact _{M2a is closed by the excitation of the relay coil M2c ,} the relay coil _M1c of the auxiliary relay _M1 is energized, the normally open contact _M1a is closed, and the auxiliary relay _M1 is self-held.
At the same time, normally closed contact M ₁ b opens and solenoid 18s
(or 18) and switch the solenoid control valve 18 to the neutral position in the same manner as described above, and then
The rotation of the rotary 8 is stopped, and the rotation of the rotary 8 is stopped. After that, when the driver finishes his urgent business and returns to the driver's seat 3, the normally closed contact 13b of the second sensor 13 is opened and the timer T's timing section is opened.
The power to TC is cut off, the normally open contact Ta is opened, and the relay coil M ₂ c of the auxiliary relay M ₂ is deenergized and the normally open contact M ₂ a is opened, but the auxiliary relay M ₁ is still self-holding. Leave it as it is,
The PTO shaft 10 is not driven and the work implement 8 does not rotate. In this way, safety in operating the working machine 8 is ensured as described above. Therefore, in this case as well, the reset switch 16 must be operated manually and the auxiliary relay
Only when the self-holding of M ₁ is released and the normally closed contact M ₁ b is closed, the solenoid 18s or 18 is energized, and the rotation of the PTO shaft and therefore the rotation of the work implement 8 can be restarted.

On the other hand, if the driver temporarily lifts his/her hips, or if the driver leaves his/her seat and reseats within the time limit set by timer T, the relay coil M ₂ c is energized, and therefore the relay coil M ₁ c is energized again. is not performed, and the rotation of the work implement 8 does not stop. In other words, if the worker is away from his/her seat for a certain amount of time and there is a possibility that he/she may forget that the rotation of the work equipment has stopped due to leaving the seat, the rotation of the work equipment will be stopped and the rotation of the work equipment will be prohibited from restarting unconsciously. .

As described in detail above, in the case of the present invention, if the driver leaves the seat for a certain period of time or more, the drive of the working machine is stopped, so there is no wastage of power and safety is improved. Even if you re-sit after leaving your seat, the machine will not suddenly resume rotation, and you will be required to operate the reset switch, so you will be reminded to check the safety of your surroundings, and you will be reminded to check the safety of your surroundings. There will be no unexpected injury to other workers.

In the above-described embodiment, when the working machine is raised and retracted and there is no need to rotate it, the drive is automatically stopped, so there is no waste of power and it is very safe.

In the above embodiment, even if the first sensor 12 is activated, the working machine can be rotated again by opening the reset switch 16, but in this case, opening the reset switch 16 is not necessary. It is also possible to configure a configuration in which this is not required.

As described above, according to the present invention, the safety of the work vehicle can be improved, and both the driver and the auxiliary worker can concentrate on their respective tasks with peace of mind.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a left side view of a tractor according to the present invention, and FIG. 2 is a circuit diagram of the main parts of the electric system and hydraulic system. 1...front wheel, 2...rear wheel, 3...driver's seat, 5...
... lower link, 6 ... top link, 7 ... lift arm, 8 ... work equipment, 9 ... hydraulic cylinder, 10 ... PTO axis, 12 ... first sensor,
13...Second sensor, 14...Battery,
M ₂ a, 12a, M ₁ a...normally open contact, 13b, M ₁ b
... Normally closed contact, Ta ... Timing contact, M ₁ , M ₂ ...
Auxiliary relay, T...Timer, 18...Solenoid control valve, 23...Manual control valve, _P1 , _P2 ...Hydraulic pump.

Claims (1)

[Scope of utility model registration request] A work vehicle equipped with a PTO shaft that drives a work machine is equipped with a sensor that detects when the driver leaves the seat, and stops driving the PTO shaft if the sensor continues to emit a detection signal for a predetermined period of time. At the same time, the sensor issued a detection signal.
A work vehicle characterized in that, when the drive of the PTO axis is stopped, the drive of the PTO axis is restarted by performing a predetermined reset operation.