JPS599368B2 - Tractor PTO system control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a PTO system control device for a tractor, and is capable of reliably controlling a PTO system when the engine load suddenly increases and the engine speed decreases during steady work with the traveling system disconnected. This system detects this and disconnects the PTO system to prevent overloaded operation of the engine and the engine stalling that accompanies it.

With tractors, there is stationary work where the drive system is disconnected and the tractor body is stopped, and power is extracted from the PTO shaft to perform the work, but in the past, the PTO system was configured to be intermittent artificially. , If the engine load suddenly increases due to some reason during work, it will be detected and P
It is not possible to disconnect the TO system, resulting in the engine being operated under overload or causing the engine to stall.

The present invention solves such conventional problems, and
Its features include a rotation speed setting device that is linked to the accelerator operation mechanism to control the engine rotation speed, a rotation speed detector that detects the engine rotation speed, and a rotation speed detection and setting value of the rotation speed setting device. A comparator that determines load fluctuations by comparing the detected value of the comparator, a control system that disconnects the PTO system based on a signal from the comparator when the engine speed decreases, and a release switch that opens and closes this control system. It has the following features.

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.
In the figure, 1 is the tractor body, mission case 2
The engine 3, bonnet 4, instrument panel 5, steering handle 6, etc. are provided at the front of the vehicle.

7 is a front wheel, 8 is a rear wheel, and 9 is a fender located inside the rear wheel 8.

10 is a hydraulic system mounted on the rear of the tractor body 1;
It has a pair of lift arms 11, and a driver's seat 12 is provided on this hydraulic device 10.

13 is a PTO shaft for driving the work machine.

Inside the mission case 2 that constitutes the tractor body 1,
As shown in FIG. 2, a traveling main transmission 14, a traveling super deceleration device 15, a traveling auxiliary transmission 16, a PTO transmission 1, 7, and
A TO hydraulic clutch 18, a PTO reduction gear 19, etc. are built-in.

The traveling main transmission 14 includes a transmission gear 22 fixedly mounted on a main shaft 21 which is connected to and connected to the engine 3 via a main clutch 20.
23, 24, 25, a traveling transmission shaft 26 supported above the main shaft 21, and a forward free rotation gear 27 loosely fitted onto the traveling transmission shaft 26 so as to always engage with the transmission gears 22, 23, 24.
, 28, 29, and the transmission gear 2 via the intermediate gear 30.
5, and each of the idle gears 27, 28, 29,
Forward hydraulic clutches 32, 33, 34 and reverse hydraulic clutch 35 for selectively coupling 31 to the traveling transmission shaft 26
It consists of:

These forward hydraulic clutches 32, 33, 34 and reverse hydraulic clutch 35 are connected to forward solenoid valves 36, 37,
Intermittent control is possible by 3B and reverse solenoid valve 39.

The PTO transmission 17 is a PT supported below the main shaft 21.
O transmission shaft 40 and transmission gears 22, 23, on the main shaft 21,
24, 41, PTO idle gears 42, 43, 44, 45 fitted on the PTO gear shift shaft 40, and idle gears 42, 43, 44. a sliding connector 46 selectively coupled to the
47, and is interlocked with the PTO shaft 13 via the PTO hydraulic clutch 18, the PTO transmission shaft 48, and the PTO speed reduction device 19.

The PTO hydraulic clutch 18 is connected to the PTO solenoid valve 4 shown in FIG.
9 allows for intermittent control.

FIG. 3 shows a block diagram of the control device. Reference numeral 50 denotes a rotation speed setting device for setting the rotation speed of the engine 3, which is composed of a potentiometer and the like that are interlocked with an accelerator lever 51.

A rotation speed detector 52 detects the rotation speed of the engine 3 as a voltage signal.

Reference numeral 53 denotes a comparator, which calculates a detection value B detected by the rotation speed detector 52 from a set value A set in the rotation speed setting device 50.
The load fluctuation for the engine 3 is determined by comparing and subtracting the values.

54 is a dead band setting device for the comparator 53, which is used to set the engine rotation speed from steady state (for example, zsoorpm) to 300 rpm.
This is to prevent the comparator 53 from issuing the cutting command C even if the voltage decreases by only fl.

55 is a PTO control circuit that controls the PTO solenoid valve 49;
6 is a PTO that gives an intermittent command D to the PTO control circuit 55;
The intermittent circuit 57 is a release switch for releasing the disconnection command C from the comparator 53.

58 is a travel control circuit that controls the electromagnetic valves 36, 37, 38, and 39, and 59 is a transmission command E to the travel control circuit 58.
This is a traveling transmission circuit that gives the following.

Next, the action will be explained.

When the traveling speed change circuit 59 is set to neutral, each electromagnetic valve 36, 37, 38, 39 is held in a demagnetized state via the traveling control circuit 58, so that the hydraulic clutches 32, 33, 3
4 and 35 both remain in the disconnected state.

In other words, the traveling main transmission 14 is in a neutral state, power is not transmitted from the traveling gear shaft 26 to the rear gear, and the tractor body 1
remains stopped.

During stationary work, the hydraulic clutches 32, 33, 3 are used as described above.
4, 35 and put the traveling main transmission 14 in a neutral state, the sliding couplings 46, 47 are connected to the idle gears 42, 43,
44 and 45, the PTO transmission 17 is shifted to a required number of gears, and a predetermined amount of power is extracted from the PTO shaft 13.

At this time, the engine speed changes from steady rotation to dead band setting device 5.
4, the comparator 53 compares the set value A set by the rotation speed setting device 50 and the detected value B of the engine rotation speed detected by the rotation speed detector 52. Although comparison and subtraction are performed, the comparator 53 does not issue a disconnection command C, and therefore the PTO hydraulic clutch 18 remains connected.

Next, when the load suddenly increases and the engine speed decreases, the detected value B of the rotation speed detector 52 becomes small accordingly.

And the decrease in engine speed at that time is 300rpIf
If it is greater than or equal to i, the comparator 53 compares and subtracts the set value A and the detected value B, determines the sudden load change, and issues a stop command C.
, the PTO control circuit 55 operates, and the PTO solenoid valve 49, which has been in an energized state, is demagnetized by a command from the PTO intermittent circuit 56.

Therefore, the PTO hydraulic clutch 18 is in a disconnected state, and the load on the engine 3 is reduced, so that overload operation of the engine 3, as well as accompanying engine stalling and wasteful consumption of fuel, can be prevented.

Note that when extracting power from the PTO shaft 13 while the tractor body 1 is running, such as during low-crit plowing work, the PTO hydraulic clutch 18 will be disconnected while the tractor body 1 is running, which will hinder the work. Release switch 5
7 cancels the disconnection command C from the comparator 53.

The release switch 57 is activated in response to the travel control circuit 58 to release the disconnection command C when any of the hydraulic clutches 32, 33, 34, and 35 is connected and the travel main transmission 14 is in a state other than neutral. It's okay.

As described above, in the present invention, the comparator compares the set value set in the setting device in conjunction with the operation of the accelerator operating mechanism and the actual detected value detected by the rotation speed detector. , engine load fluctuations can be reliably detected.

In addition, since the engine speed is detected by a detector, compared to a system that determines the load condition based on torque fluctuations,
The structure of the detector and comparator is extremely simple and can be easily assembled into an engine or the like.

In addition, since the PTO system is configured to automatically disconnect when the engine speed decreases due to load fluctuations, it is possible to prevent overloaded operation of the engine, and also to prevent engine stalling or wasteful fuel consumption due to this. can.

In addition, a release switch is provided to open and close the control system, so it can be used depending on the purpose of the work.For example, when the load increases during row plowing work, the drive system can be changed without disconnecting the PTO system. This is very useful in cases where it is sufficient to stop the

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, with FIG. 1 being a side view of the whole, FIG. 2 being a configuration diagram of a power transmission system, and FIG. 3 being a block diagram of a control device. 1...Tractor body, 3...Engine, 13...PTO shaft, 14...Travel main transmission, 17...PTO shift Device, 18...
...PTO hydraulic clutch, 49...PTO
Solenoid valve, 50... Rotation speed setting device, 52...
...Rotation speed detector, 53...Comparator, 55...
...PTO control circuit, A...Setting value, B...
...detected value. C... Cutting command.

Claims (1)

[Claims] 1. A rotation speed setting device linked to an accelerator operation mechanism for controlling engine rotation speed, a rotation speed detector for detecting the engine rotation speed, and a setting value of the rotation speed setting device and a detected value of the rotation speed detector. A comparator that compares and determines load fluctuations, and a signal from the comparator that activates the PT when the engine speed decreases.
P of a tractor characterized by comprising a control system for disconnecting the O system and a release switch for opening and closing this control system.
TO system control device.