FR2762069A1 - TRACTOR POWER TAKE-OFF EMERGENCY STOP PROCEDURE AND DEVICE - Google Patents

Abstract

The invention relates to a method and a device for emergency stop of the tractor PTO. According to one embodiment, the emergency stop device consists of a photocell (20) and a reflector (21), arranged so that the reflector (21) is masked by the driver, when the latter is seated on his seat (12). Main application: agriculture.

Description

The invention relates to a method and a device for emergency stopping of the tractor PTO.

Agricultural tractors are currently designed to directly implement agricultural equipment, the most common of which are fixed to the rear of the tractor by means of a three-point hitch, allowing the height and tilt adjustment of the so-called equipment, and are driven by the tractor engine via a special transmission, called "PTO": some equipment, heavier and more bulky, is towed by the tractor, while still being connected to the PTO.

It is understood that the PTO must be able to be started and stopped at will during the operation of the main engine. For this, the PTO is generally equipped with a passive start-up device, by electro-hydraulic control switch located in the driver's cab.

However, during agricultural work, it sometimes happens that the driver of the tractor is brought to immobilize it, after having put the engine in neutral and leaving it running, in order to be able to descend and go to the rear to perform some checks or interventions on the agricultural equipment in service, keeping it in operation.

During these interventions, the driver may have to return to the cabin several times to stop and restart the PTO; Also, some manufacturers have recently mounted, on the rear of the tractor, on one of the rear wings of the latter, a control unit allowing direct action on the electro-hydraulic control of the intake strength.

Although this device greatly facilitates interventions during work, it does not constitute a safety device for the operator working on equipment to adjust, clean or unclog it; also, drivers are often caught in such interventions not requiring that the PTO be stopped beforehand. Such accidents often have a fatal outcome, because, generally, no one is on the scene to stop the PTO and intervene to release the victim, who could not, given the suddenness of the snap, reach the PTO control unit, located at the rear of the tractor, when the tractor has one.

Various safety devices are already known, intended to avoid accidents that may result from a loss of control of a motorized vehicle, such as a tractor, when the driver becomes unwell: these are "dead man" devices , well known in industry and public works, intended either to cause the shutdown or to prohibit the entry into service of certain organs in particular circumstances.

French patent application 2 233 200 describes a safety device for dynamic assemblies, controlled by a manual operating member, such as a steering wheel, which, in this case, comprises rings connected to a delay device, for the purpose to prevent the unwanted release of a safety device, that is to say when the steering wheel plug is released momentarily. Beyond a certain time, if the steering wheel is released, a relay causes the engine to stop and, consequently, the vehicle to stop. However, such a device requires almost permanent contact of the fingers on the two conductive rings; which excludes the wearing of gloves and slackening of the steering wheel even during stabilized straight paths. The use of this device requires a minimum of concentration on the part of the driver, who distracts him from monitoring work in progress, because any untimely operation of the device causes the engine to stop and, consequently, the PTO, with the repercussions that we imagine on the work in progress.

French patent 2,555,522 describes a safety device aimed both at permanently monitoring the physical state of the driver of a motorized vehicle and at causing the slowing down or stopping of said machine, or of equipment. moved by it, when certain pre-established conditions are no longer met.

This device, consisting essentially of light transmitters and receivers, arranged on the crown of the steering wheel or on the hub cover of the latter, constitutes, in fact, an improved "dead man" system , which forces the driver, as in the previous case, to worry about maintaining a certain attitude in terms of driving the machine, which can be considered excessive when it is an agricultural tractor, making journeys repetitive straight lines in fields, subjected to work requiring some attention on the part of the driver.

In the field of PTO safety, French patents 2,393,693 and 2,498,534 describe a device ensuring the automatic stopping of the motor of a tiller, when the driver releases both handles of the handlebars reverse gear, and only in this case. Given its design, such a device cannot be transposed to an agricultural tractor, for which, moreover, the same problem does not arise.

 It has also been developed, by a manufacturer of an agricultural tractor, an automatic PTO management system, which disconnects the latter when the three-point hitch supporting a implement is raised. However, this system still allows human intervention on the tool, while the PTO remained engaged.

The object of the present invention is to remedy the drawbacks presented by current safety devices, concerning the PTO of tractors. This invention, as it is characterized, solves the problem of defining a method and creating a safety device for a tractor PTO, with which, on the one hand, any exit of the driver from the driving cab of the tractor causes the PTO to stop, when it has remained in operation, and, on the other hand, does not impose any constraint or discomfort on the driver, when he is at his post conduct.

The emergency shutdown process for a tractor PTO when the driver leaves the operator's position is mainly characterized by the fact that it a) detects the absence of the driver from his driving position, b) cause the PTO to stop, as soon as the absence of the driver from his driving position is detected, c) keep the PTO stationary when the driver is absent driver of his driving position, d) prohibit any resetting according to the PTO, without the presence of a person at the driving position.

According to a first solution, the device for emergency stop of the power take-off of a tractor when the driver leaves his driving position, according to the process developed above, is characterized in that it consists of a photoelectric cell and a reflector, arranged so that the reflector is hidden by the driver, when the latter is at his driving position.

According to a second solution, the PTO emergency stop device consists of several electrical contactor buttons, regularly distributed on the steering wheel, connected in parallel to two concentric circular electrical conductors integrated in the steering wheel, connected to the terminals of a relay controlling the power-up of the electro-hydraulic switch to activate the PTO.

According to a third solution, the PTO emergency stop device consists of a micro-switch, placed in the gearbox, on the path of the neutral shift fork, so that the said microswitch is requested at the end of travel of said fork.

The advantages obtained thanks to this invention consist essentially in that any direct intervention by the driver on a machine or equipment driven by the PTO, while the latter has remained in operation, is impossible, as is all resetting from a remote control unit, located on one of the rear fenders of the tractor, or on the main control unit, located near the operator's station, when this is not occupied.

Other characteristics and advantages will appear in the following description of each of the three emergency stop devices according to the invention, given by way of non-limiting example, with regard to the appended drawings in which - Figure 1 represents a front view, in cross section, of a tractor equipped with an emergency stop device with photocell, - Figure 2 shows a schematic top view of a steering wheel equipped with a emergency stop with touch switch buttons mounted on the steering wheel, - Figure 3 shows a top view, in partial section, of a gearbox fitted with an emergency stop device, - Figure 4 shows the diagram of the electrical connection of the emergency stop device with the power supply and control circuit of the electro-hydraulic switch to activate the PTO.

By examining, now, successively, each of the figures, we notice that
FIG. 1 represents a tractor 10, the cabin 11 of which is equipped, on the right side, with a photoelectric cell 20 and, on the left side, with an optical reflector 21, these two devices having been fixed at a height such that the light beam 22, shown in phantom, is interrupted by the presence of the driver, when the driver is seated in the driving seat 12. Thus, any activation of the PTO will be prohibited in the absence of the driver from his driving position and
The immediate stopping of the said PTO will be obtained as soon as the driver has left the driving seat. This solution has the advantage of great flexibility and ease of adaptation to all types of tractors, without the need to replace, or modify, parts or equipment originally fitted by the constructor. Another arrangement, relative to the driving seat 12, of the photoelectric cell 20 and the optical reflector 21 can, of course, be envisaged, provided that the reflector 21 remains hidden when the driver is at his driving position.

FIG. 2 represents a flywheel 30, provided with two concentric circular conductors 31 and 32, interconnected by tactile contact buttons 33, 34, 35, here three in number, arranged 120 from one another, mounted in parallel on the circular conductors 31, 32, so that any tactile action on the part of the conductor, on at least one of said contactor buttons, causes a short-circuiting of the circular conductors 31, 32, the one is connected directly to one of the terminals of the electrical circuit and the other of which is connected to the opposite terminal by means of a relay controlling the energization of the electro-hydraulic switch for activating the PTO. Thus, when the driver's hands leave the steering wheel 30, the electrical connection between the two circular electrical conductors 31, 32 is broken, the relay, being then de-energized, cuts the electrical supply to the activation switch, which causes the PTO to stop immediately, or delayed, by a delay device. Various means, existing in the prior art, can be used to ensure the connection between the circular conductors 31, 32 and the electrical circuit for controlling the power take-off, such as: conductive rotating ring fixed to the steering wheel rod , on which bear coals fixed to the steering column; a two-conductor wire, loosely wound around the steering column, etc.

FIG. 3 represents a gearbox 40, provided with a microswitch 41 disposed on the path of the fork 42 ensuring the neutral gear of the gearbox, so that the contact of the fork 42 with the microswitch 41 is only ensured at the end of the stroke, which de-energizes the relay controlling the electro-hydraulic switch for putting the PTO into function.

FIG. 4 represents the wiring diagram of the emergency stop device connected to the relay 50 controlling the energization, by means of the battery 51, of the electro-hydraulic switch 52 for operating the outlet. by force.

As can be seen, the contactor (not shown) of the emergency stop device is connected directly to one of the terminals (+) of the battery 51, on the one hand, and, on the other hand, to the other terminal (-) of the battery 51, by means of a relay 50 mounted in series with the emergency stop device, so that when the energization of the relay 50 is interrupted by the contactor of the stop device, the said relay de-energizes the electro-hydraulic interrupter 52. A delay device 53 can be mounted in series between the stop device and the relay 50, in order to avoid any untimely stopping of the PTO due to a fleeting contact breakage resulting from a lack of attention from the tractor driver.

The emergency stop device according to the invention is intended, mainly, to equip agricultural tractors and other agricultural machines, such as: combine harvesters, self-propelled beets and self-propelled maize for example, but nothing would stand in the way to its application to non-agricultural machinery, generating the same problems.

Claims (5)

 izievenuications  7. Process for emergency stopping of the PTO of a tractor when the driver leaves the driving position thereof, characterized in that it consists in - detecting the absence of the driver from his driving position , - cause the PTO to stop, as soon as the absence of the driver from his driving position is detected, - keep the PTO at a standstill, during the absence of the driver from his driving position , - prohibit any activation of the PTO, without the presence of a person in the driving position. 2. Emergency stop device for the PTO of a tractor when the driver leaves his driving position, implementing the method according to claim 1, characterized in that it consists of 'a photocell (20) and a reflector (21). 3. Device according to claim 2, characterized in that the photoelectric cell (20) and the reflector (21) are arranged so that the reflector (21) is hidden by the conductor, when the latter is seated on his seat (12). 4. Emergency stop device for the PTO of a tractor when the driver leaves the driving position thereof, implementing the method according to claim 1, characterized in that it consists of several tactile electrical contactor buttons (33, 34, 35), regularly distributed on the steering wheel (30), connected in parallel to two concentric circular electrical conductors (31, 32), integrated into the steering wheel (30), connected to the terminals of a relay (50) controlling the energization of the electro-hydraulic switch (52) for putting the PTO into service. 5. Emergency stop device for the PTO of a tractor when the driver leaves the driving position thereof, implementing the method according to claim 1, characterized in that it consists of 'A micro-contactor (41), disposed in the gearbox (40), in alignment with the fork (42) in neutral transmission.