JPH0342221B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic safety braking system for a power shift transmission vehicle for road work.

In general, this type of power shift transmission vehicle selects the gear position using hydraulic pressure. Therefore, if the vehicle were to stall on a slope or the like, the hydraulic power source for selecting the gear would also stop at the same time. This caused the car to go into the same state as if the clutch had disengaged, so unless the brakes were applied again, the car would roll down the slope without permission, leading to an unexpected accident.

In addition, if the same work vehicle is configured with a combination of a power shift transmission and a hydrostatic transmission, when stopping on a slope, simply move the forward/reverse lever of the hydrostatic transmission to the neutral position. A stopped state can be maintained. Therefore, even when stopping on a slope, the vehicle is often stopped by operating the above-mentioned operation, that is, by setting the forward/reverse lever of the hydrostatic transmission to the neutral position, without stepping on the brake. However, if the above vehicle also stalls on a slope, the hydraulic power source for the power shift transmission will run out. As a result, the same condition as described above occurs when the clutch is disengaged, and the vehicle, which had been stopped on the slope until then, begins to descend the slope as soon as the engine stops, resulting in the same result as described above. It was hot.

Furthermore, in vehicles such as road cutters where the operator works away from the driver's seat, there is a problem that if the engine stops while working on a slope, the vehicle will start to descend down the slope. Ta.

In order to improve this, it is possible to consider a principle in which stopping of the engine is detected at the same time as the stopping of the engine, and a braking device is actuated based on the detection signal. That is, engine stoppage can be detected by using engine oil pressure and by using a main braking device (air brake) as a braking device. Specifically, as shown in FIG. 1, a 2-position electromagnetic directional control valve 3 is provided in the pilot pressure circuit P of a conventional braking system in which a foot-operated brake valve 1 and an air tank 2 are connected. Even if the engine is not activated, the two-position electromagnetic directional control valve 3 is activated by the engine stall signal and the pressure in the air tank 2 is guided to the pilot pressure circuit P, and the brake cylinder 5 is activated by the relay valve 4 being activated. This system automatically applies braking when the engine stalls.

However, the above principle causes the brake to always be applied even when the engine is not running, so it cannot be optimal under the above-mentioned circumstances. Therefore, it has been a long-standing challenge in this type of industry to develop a device that automatically applies a desired braking action only when the engine stops for some reason when the engine of the above-mentioned road work vehicle is in operation.

This invention solves the above-mentioned problems in the above-mentioned power shift transmission vehicles, vehicles in which a power shift transmission and a hydrostatic transmission are combined, and vehicles in which an operator works at a location away from the driver's seat. It was also made to solve the problems of developing a device based on the above-mentioned principle at once, and its purpose is to automatically apply a braking action when the engine unexpectedly stops after the engine has been started.
Vehicle safety can be ensured on slopes, etc., and the starter switch can be turned off after the engine has stopped.
To provide an automatic safety braking device for a power shift transmission vehicle that can automatically release the braking mechanism when the engine is restarted or when the engine is restarted.

Embodiments of the present invention will be described below based on the accompanying drawings. Each of the embodiments is based on the principle mechanism shown in FIG. 1, but this is omitted in the drawings of each embodiment, and the explanation will be given using the same reference of FIG. 1. Further, in the drawings of each embodiment, common or corresponding parts will be described using the same reference numerals.

FIG. 2 shows a first embodiment of the device according to the invention.

To explain the configuration of this first embodiment, in the same braking mechanism A as shown in FIG. At both ends 10 and 11, there is a series circuit B consisting of the solenoid 3a of the two-position electromagnetic directional control valve 3, the engine oil pressure switch 7, and the normally open contact 8a of the relay 8.
ON when the starter switch is turned one step in conjunction with the relay and the starter switch.
Both ends of the series circuit C are connected to the second switch 6x of the starter switch, which is turned off when the switch is in the position, and turned on when the starter switch is turned two steps. Further, a connection point 13 between the engine oil pressure switch 7 and the normally open contact 8a of the relay in the series circuit B is connected to a connection point 12 between the relay 8 and the starter switch 6x in the series circuit C. In addition, the first switch 6 of the relay 8 is ON.
By doing so, the second switch 6x is activated and the relay 8 is energized.Even if the second switch 6x is removed, current is supplied to the relay 8 from the normally open contact 8a side, so the normally open contact 8a is It remains closed. (This is a so-called self-holding circuit.) Due to the above configuration, in this first embodiment, the safety braking system does not yet operate just by turning on the first switch 6 linked to the starter switch of the main switch. With the interlocking participation of the second switch 6x of the starter switch by the circuit C, the relay 8 is activated as soon as the engine starts to start, so that the safety braking system becomes functional. Therefore, even if the starter switch mentioned above returns from the starting position to the ON position,
Since the relay 8 described above maintains the circuit, the system can remain functional.

In this state, if the engine is stopped for some reason, the oil pressure decreases, the engine oil pressure switch 7 is turned on, and the solenoid 3a is energized. Therefore, since the two-position electromagnetic directional control valve 3 is switched, air pressure is directly supplied from the air tank 2 to the pilot pressure circuit P, and the brake is activated by the operation of the relay valve 4, without operating the brake valve 1. In other words, the brakes are automatically applied at the same time as the engine stalls.

Next, when the engine is restarted, the oil pressure increases and the engine oil pressure switch 7 turns OFF.
Therefore, the power to the solenoid 3a is cut off and the brake is automatically released. At this point, the relay 8 is still in the circuit holding state, so even if the engine stalls again, the safety braking device will automatically operate in the same way. According to the above two examples, even if the vehicle encounters an unexpected situation where the engine stalls while working on a slope, the vehicle can be kept stopped and the road work can be continued in a stable condition.

Also, if you stop the engine at this point, the brakes will be applied automatically, but by turning starter switch 6 of the main switch back to OFF, the relay holding power will be cut off, so relay 8 will return to the holding release state. Therefore, the power to the solenoid 3a is cut off, and the braking mode by the safety braking device is automatically released.

The automatic safety braking system works immediately after the engine starts until the oil pressure rises, but when the oil pressure rises due to engine operation, the engine oil pressure switch 7 is turned off, so the solenoid 3a is no longer energized. When the safety brake is disconnected, the safety braking device is automatically released. The embodiment described above allows the safety braking device to remain in a deactivated state while the engine is running. As a result, the vehicle can smoothly and freely perform road work on this slope without receiving any braking action under conditions other than when the engine stalls.

FIG. 3 shows a second embodiment of the device according to the invention.

To explain the configuration of this second embodiment, in the same braking mechanism A as described above, both ends 1 of a series circuit of a first switch 6 interlocked with a starter switch, which is the main switch of the mechanism A, and a DC power source E.
0 and 11, instead of the second switch 6x linked to the starter switch shown in the first embodiment, an engine oil pressure switch 9 which is turned on when the oil pressure increases is placed at this position. The structure is exactly the same as that of the first embodiment. The operating pressure of the switch 9 is set slightly higher than that of the engine oil pressure switch 7 located below.

Due to the above-mentioned configuration, in this second embodiment, the automatic safety braking system is activated only when the engine is stopped after operation. Therefore, it is possible to eliminate the redundant process in which the safety braking device is momentarily activated at the time of starting the engine and then released immediately as in the first embodiment. In this embodiment, the first
As in the embodiment, even if the vehicle encounters an unexpected engine stall while working on a slope, the vehicle remains stopped and road work can be continued in a stable condition, and there is no problem other than the engine stalling. Under these conditions, road work can be carried out smoothly and freely without any braking action.

In both of the above two embodiments, automatic safety braking devices for power shift transmission vehicles have been described, but the present invention is not limited to the above-mentioned power shift transmission vehicles, and can be applied to the above-mentioned systems. Even when the present invention is implemented as an automatic safety braking system for a vehicle using a combination of a power shift transmission and a hydrostatic transmission, the same effects as those of the above embodiments can be obtained.

As explained above, in this invention, engine stoppage is detected by engine oil pressure, and the braking device uses a conventional main braking device.A two-position electromagnetic directional control valve is provided in the pilot pressure circuit of the braking device. In the braking mechanism, a solenoid of the two-position electromagnetic directional control valve and an engine oil pressure valve that is closed when the engine oil pressure is lowered are connected to both ends of a series circuit between a first switch linked to the starter switch in the mechanism and a DC power source. In addition to connecting the power switch and the series circuit B of the normally open contact of the relay in parallel, the relay works in conjunction with the starter switch, and when the starter switch is turned one step and is in the ON position, the starter A series circuit C is connected to a second switch of the starter switch that turns on when switch 2 is turned two steps, or an engine oil pressure switch that turns on when the oil pressure increases instead of this second switch, and further, A connection point between the normally open contact of the relay in the series circuit B and the oil pressure switch, and a second connection point between the relay and the starter switch in the series circuit C.
By connecting the connection point with the switch or the engine oil pressure switch, automatic braking is performed when the engine suddenly stops repeatedly after the engine has been started. Since the safety of the vehicle on slopes etc. can be ensured by this function, traffic accidents caused by reckless driving etc. can be reliably prevented. Furthermore, in vehicles such as road cutters where the operator works away from the driver's seat, if the engine stalls for some reason while working on a slope, the operator must quickly return to the driver's seat and apply the brakes. However, by equipping a vehicle with the above-mentioned device, the braking device will automatically operate in the event of an unexpected engine stop, which often occurs, thereby greatly improving the safety of road work.

[Brief explanation of drawings]

The attached drawings are embodiments of the present invention, in which Figure 1 is a schematic diagram showing the principle mechanism of braking that is the basis of the device of the invention, and Figure 2 is a first implementation of the device of the invention using the mechanism shown in Figure 1. FIG. 3 is a detailed view of a main part showing a second embodiment of the device of the present invention in the mechanism shown in FIG. 1. 1...brake valve, 2...air tank, 3...2
Position electromagnetic directional control valve, 3a... Solenoid, 4... Relay valve, 5... Brake cylinder, 6... First switch linked with starter switch, 6x... Second switch linked with starter switch, 7, 9...
Engine oil pressure switch, 8... Relay, A... Braking principle mechanism, B, C... Series circuit, P
...Pilot pressure circuit.

Claims (1)

[Scope of Claims] 1 Engine stoppage is detected by engine oil pressure, and the braking device uses a conventional main braking device.The braking device is a braking mechanism in which a two-position electromagnetic directional control valve is provided in the pilot pressure circuit of the braking device. In the above mechanism, the first switch linked with the starter switch
At both ends of the series circuit between the switch and the DC power source, the solenoid of the two-position electromagnetic directional control valve, the engine oil pressure switch that closes when the engine oil pressure drops, and the normally open contact of the relay are connected in series. A second switch of the starter switch that works in conjunction with both ends of circuit B, the relay, and the starter switch to turn off when the starter switch is in the ON position when the starter switch is turned one step and turn ON when the starter switch is turned two steps. and a connecting point between the normally open contact of the relay in the series circuit B and the engine oil pressure switch, and a second terminal interlocked with the relay in the series circuit C and the starter switch. An automatic safety braking device for a power shift transmission vehicle, characterized in that it is configured by connecting a connection point with a switch. 2 Engine stoppage is detected by engine oil pressure, and the braking system is a braking system that uses a conventional main braking system and is equipped with a two-position electromagnetic directional control valve in the pilot pressure circuit of the braking system. The first one linked to the switch
At both ends of the series circuit between the switch and the DC power source, the solenoid of the two-position electromagnetic directional control valve, the engine oil pressure switch that closes when the engine oil pressure drops, and the normally open contact of the relay are connected in series. Both ends of circuit B are connected to both ends of a series circuit C between the relay and an engine oil pressure switch that closes when the engine oil pressure rises, and A power shift transmission vehicle characterized in that a connection point between an open contact and an engine oil pressure switch, and a connection point between a relay in the series circuit C and an engine oil pressure switch are connected. Automatic safety braking system.