JPH08159107A - Automatic control device for road roller - Google Patents

Abstract

PURPOSE: To instantaneously impede free rotation of an oil hydraulic motor, so that an accident can be prevented before its occurrence, by connecting a switching valve of closing a hydraulic circuit in the case of decreasing a pilot pressure to a prescribed value or less. CONSTITUTION: When rollers 1a, 1b are in advance running, for instance, along an ascending slope, due to a trouble of an engine 3 or a transmitting mechanism 5 and the like in the halfway of the slope, when an oil hydraulic pump 7 is not rotated or placed in a condition of decreasing an output, pressure oil from a pilot circuit 17 is interrupted or decreased to a prescribed value or less. Here is a cutoff path 15 of a shutoff switching valve 13 in conduction to a connecting circuit 19 by a cam of a spring 16, and a flow of pressure oil in hydraulic circuits 8, 9 is interrupted to instantaneously stop rotating oil hydraulic motors 2a, 2b. An emergency controlling switching valve 18 for cutting off the pilot circuit 17 itself, in the case of generating the situation that an operator is interposed between a machine body handle and an obstacle behind during reversing a machine body, is provided in the pilot circuit 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic controller for a road roller used for compacting a roadbed or a pavement surface, and more particularly to a sudden engine stop while the road roller is working on a slope such as a slope. To prevent an abnormal situation where the roller rolls out of control due to the cause of an accident, or an emergency situation where the operator gets caught between the steering wheel and an obstacle behind the vehicle while the aircraft is moving backward. The present invention relates to an automatic control device.

[0002]

2. Description of the Related Art Conventionally, a load roller used for compacting a roadbed or the like, as a traveling means of the roller, drives a hydraulic pump by the power of an engine mounted on the machine body to generate fluid energy, and this fluid energy is transferred to the front wheels. A system is adopted in which hydraulic pressure is provided to the rollers and rear wheel rollers, and the front and rear wheel rollers are rotated by the respective hydraulic motors.

Further, as a load roller driven by the hydraulic motor, a large roller that allows an operator to ride on the machine to operate traveling, and a roller that protrudes behind the machine while the operator walks without getting on the machine. There is a small roller of a hand guide type that operates a handle.

In the case of the large roller described above, since a large engine that can be started by a starter motor is used, even if the engine and the hydraulic pump are directly connected by a coupling, a starting force can be directly applied to the engine. However, in the case of a hand-guided small roller, a small engine that starts with a crank handle or a recoil starter is used, so if the hydraulic pump is directly connected to the engine, the hydraulic pump becomes a load and it is difficult to start the engine. , Therefore, a centrifugal clutch is provided between the engine and the hydraulic pump to prevent the starting rotational force of the engine from being transmitted to the hydraulic pump, and after the engine has started and reached a predetermined rotational speed, its rotation is transmitted through the centrifugal clutch. Is transmitted to the hydraulic pump.

Furthermore, in the case of a hand-guided small roller, an emergency situation may occur in which the operator is caught between the steering wheel and an obstacle behind the vehicle during reverse operation. As a countermeasure against this, conventionally, when a lever-shaped protrusion is provided behind the handle and the operator tries to be sandwiched between the handle and the obstacle, the protrusion is pushed forward and the traveling lever for operating the aircraft is operated. A safety device is provided that pushes back to the neutral position.

[0006]

By the way, in such a load roller, since the driving force of the hydraulic motor is used as the driving source of the roller, some cause, for example, during working on a sloped road such as a slope, If the connection between the input shaft of the hydraulic pump and the output shaft of the engine is damaged and the hydraulic pump suddenly becomes free without receiving the power of the engine, the weight of the rollers causes the hydraulic motor to This causes pressure oil to be pumped in the opposite direction from the hydraulic motor to the hydraulic pump, causing the hydraulic pump to rotate, which may cause an accident such that the airframe runs uncontrollably like rolling down a sloping ground. is there.

Further, such an abnormal situation occurs in the case of a small roller provided with a centrifugal clutch between the engine and the hydraulic pump, such as when the engine stalls on a sloping ground during work traveling or when the engine rotation is lowered during traveling. This occurs when the centrifugal clutch is no longer effective, power cannot be transmitted due to a failure of the centrifugal clutch, or the aircraft cannot be controlled due to damage to the hydraulic pump or the piping of the traveling system. To do.

Of course, whether the roller is a large roller or a small roller, the machine body is provided with a brake device, and therefore, when an abnormal situation occurs due to the above-mentioned cause, the brake device may be operated. In particular, in the case of a small roller, the operator walks from behind the roller, so that it is often impossible to quickly operate the brake device when an abnormal situation occurs.

Further, in the case of a small roller, as a countermeasure against an accident in which the operator is caught between the handle and the rear obstacle during the backward movement, the above-mentioned safety device using the lever-like protrusion is provided. However, with such a safety device, when the operator is caught between the steering wheel and the obstacle, he can quickly release the traveling lever, but the lever is kept in the reverse position. , Even if the lever-shaped protrusion of the safety device is activated, the traveling lever cannot be returned to the neutral position and the aircraft cannot be stopped. Also, even if the operator releases the travel lever and returns to the neutral position at the moment when the operator is caught between the steering wheel and the obstacle, the aircraft will not momentarily stop at that position and will be in inertial travel. Since it moves to the rear, it has a problem that it is likely to cause a serious accident.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems in the conventional road roller, the present invention provides:
When the hydraulic pump cannot receive the power of the engine due to the cause of failure and suddenly becomes free, pressure oil flows back from the hydraulic motor to the hydraulic pump. In the event of an accident such as being caught between a rear obstacle and a rear obstacle, the hydraulic motor is momentarily blocked from free rotation, causing runaway on a sloping ground, and the operator's contact with the rear obstacle. It is an object of the present invention to provide an automatic control device capable of preventing an accident that is caught between the two.

As a means for achieving such an object, the present invention relates to a hydraulic roller for connecting a hydraulic pump and a hydraulic motor in a load roller driven by a hydraulic motor rotated by pressure oil from the hydraulic pump. A shut-off switching valve having a flow path and a cutoff path, which are opened by hydraulic oil of a predetermined pressure by a pilot circuit on the hydraulic pump side, and are closed when the pressure oil by the pilot circuit shuts off or drops below a predetermined pressure. The operation handle on the rear side of the machine body is provided with a switching valve for emergency stop which opens and closes the pilot circuit by operating a protruding spool.

[0012]

In this road roller, during normal traveling, when the emergency switching valve of the pilot circuit provided on the steering wheel is set to the open position and the hydraulic pump is driven, the predetermined pressure sent from the pilot circuit on the hydraulic pump side is set. Since the pressure oil operates the shutoff switching valve of the hydraulic circuit to the open circuit side, the pressure oil sent from the hydraulic pump through one hydraulic circuit is
After the hydraulic motor of the roller is rotated, it circulates so as to return to the hydraulic pump via the other hydraulic circuit.

While the load roller is working on a slope such as a slope, the hydraulic pump suddenly becomes free without receiving the power of the engine due to some cause of failure, or the pressure of the hydraulic pump drops. In such a situation, the hydraulic motor acts as a pump due to the weight of the rollers, and the pressure oil that had been flowing from the hydraulic pump to the hydraulic motor by one of the hydraulic circuits until now becomes the hydraulic pump from the hydraulic motor. By flowing back in the direction of, the aircraft will start to run away like rolling down the sloping ground.

When such an abnormal situation occurs, the hydraulic pump becomes free without receiving the power of the engine, or the pressure of the hydraulic pump drops, and the pilot circuit on the hydraulic pump side Since the pressure of the pressure oil that maintains the switching valve in the open state suddenly drops below a predetermined pressure, the shutoff switching valve is automatically switched to the closed state by the spring, and as a result, the hydraulic motor is switched to the hydraulic pump. Since the pressure oil flowing in the direction is immediately blocked to prevent the rotation of the hydraulic motor, the runaway of the airframe is surely controlled.

When a situation occurs in which the operator is caught between the steering wheel and a rear obstacle during the reverse operation of the aircraft, the emergency switching valve of the pilot circuit provided on the steering wheel is operated by the operator. It is pushed by the body of the switch to switch to the closed side, and as a result, the pressure oil in the pilot circuit is shut off and the shutoff switching valve is closed, so that the pressure oil flowing in the direction of the hydraulic motor is immediately blocked, and instantaneously. Free rotation of the hydraulic motor is blocked.

[0016]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows a front wheel roller 1a and a rear wheel roller 1b.
2 is a hydraulic circuit diagram that constitutes an automatic control device provided in a hand-guide type load roller provided with hydraulic motors 2a and 2b, respectively, 3 is an engine, 4 is a hydraulic pump device, and rotation of the engine 3 is a centrifugal clutch. Alternatively, it is transmitted to the hydraulic pump 7 provided with the swash plate 6 of the hydraulic pump device 4 via a transmission mechanism 5 such as a coupling.

The hydraulic pump device 4 comprises a hydraulic pump 7
A hydraulic circuit 8 connected to the hydraulic motor 2a of the front wheel roller 1a from the port A, and a hydraulic circuit 9 connected to the hydraulic motor 2b of the rear wheel roller 1b from the port B of the hydraulic pump 7. 7 is provided with an auxiliary pump 10 such as a charge pump, and is composed of a swash plate type variable piston pump having a relief valve 11 and a check valve 12 between the hydraulic circuit 8 and the hydraulic circuit 9. There is.

A connecting circuit 19 is provided between the hydraulic motor 2a for the front wheel roller 1a and the hydraulic motor 2b for the rear wheel roller 1b.
The hydraulic circuit 8 and the hydraulic circuit 9 are connected to each other to form a series circuit, and the hydraulic circuit 8 is connected to the connecting circuit 19.
A shutoff switching valve 13 including a flow path 14 for opening and closing the hydraulic circuit 9 and a cutoff path 15 is connected.

The shutoff switching valve 13 is provided in the shutoff path 1.
5 has a spring 16 on the side, and a flow path 14 side is connected to a pilot circuit 17 connected to an auxiliary pump 10 such as a charge pump provided alongside the hydraulic pump 7. When the engine 3 is started, the hydraulic pump 7 is connected. When is rotated, the pressure oil from the hydraulic pump 7 is sent to the hydraulic motor 2a through one hydraulic circuit, for example, the hydraulic circuit 8, but at the same time the pressure oil from the pilot circuit 17 connected to the charge pump 10 is supplied. Shutoff switching valve 1 at a specified pressure
3 is sent to the flow passage 14 side, the spring 16 is pushed down by this pilot pressure, the flow passage 14 side is electrically connected to the connecting circuit 19, and the pressure oil from the hydraulic pump 7 is supplied to the hydraulic circuit 8, the connecting circuit 19 and the hydraulic pressure. The circulation returning to the hydraulic pump 7 through the circuit 9 is repeated.

When the rollers 1a and 1b are traveling forward along an uphill road due to such pressure oil circulation, the hydraulic pump 7 may not rotate due to a failure of the engine 3 or the transmission mechanism 5 in the middle of the uphill road. When the pressure of the pressure oil sent from the pilot circuit 17 is cut off or drops below a predetermined value, the shut-off passage 15 of the shut-off switching valve 13 causes the shut-off switching valve 13 to shut off due to the force of the spring 16. 19, the flow of pressure oil in the hydraulic circuits 8 and 9 is cut off, and the rotations of the hydraulic motors 2a and 2b are instantaneously stopped.

Further, the pilot circuit 17 is shut off when the operator is caught between the handle and the obstacle behind the aircraft while the vehicle is moving backward. A switching valve 18 for emergency control is provided.

This emergency control switching valve 18 includes a spool 2
It consists of a 3-port 2-position switching valve by a position stop system that is opened and closed by means of 1, and as shown in FIG. 2, the spool 21 is attached to the operation handle 20 at the rear of the machine body so as to project rearward. , The spool 21 is pulled rearward so that the flow path 22 is connected to the pilot circuit 17 and the pressure oil is flowing toward the shutoff switching valve 13. However, as described above, the operator makes a mistake while the vehicle is moving backward. When a situation occurs in which the spool 21 is caught between the handle and the obstacle behind, the spool 21 comes into contact with the operator's body and is pushed, so that the cutoff path 23 is electrically connected to the pilot circuit 17 and the pilot circuit 17 is operated. The circuit 17 is cut off.

As a result, in the shut-off switching valve 13, the pressure oil from the pilot circuit 17 is shut off, so that the shut-off passage 15 side is electrically connected to the connecting circuit 19 by the force of the spring 16, and the hydraulic pressure via the connecting circuit 19 is increased. The flow of pressure oil in the circuits 8 and 9 is cut off, and the rotations of the hydraulic motors 2a and 2b are instantaneously stopped.

When the rollers 1a, 1b are made to travel forward, pressure oil is operated from the port A of the hydraulic pump 7 by the operation of the swash plate 6 of the hydraulic pump 7 via the hydraulic circuit 8, the connecting rotation 19 and the hydraulic circuit 9. Return to port B of hydraulic pump 7.
Further, when the roller 1 travels backward, the hydraulic pump 7
The swash plate 6 is switched to return the pressure oil from the port B of the hydraulic pump 7 to the port A of the hydraulic pump 7 via the hydraulic circuit 9, the connecting rotation 19 and the hydraulic circuit 8.

In the above embodiment, the charge pump 10 is used as an auxiliary pump for sending pressure oil to the switching valve 13 of the hydraulic circuit through the pilot circuit 17.
The auxiliary pump is not necessarily limited to the charge pump, and may be a vibration hydraulic pump for vibrating the roller 1 or a hydraulic pump used for steering operation.

[0026]

As described above, according to the present invention, the hydraulic circuit that connects the hydraulic pump and the hydraulic motor of the roller receives the predetermined pilot pressure from the pilot circuit on the hydraulic pump side and opens the hydraulic circuit. Since a switching valve that closes the hydraulic circuit when this pilot pressure drops below a predetermined value is connected, the hydraulic oil supply from the hydraulic pump stops due to the cause of failure on the hydraulic pump side during work traveling on slopes. If the pilot pressure on the hydraulic pump side drops below a specified value due to a sudden drop in pressure, the switching valve in the hydraulic circuit will automatically switch to the closed side, and the rotation of the hydraulic motor will stop immediately. As a result, it is possible to prevent the occurrence of danger associated with a runaway accident, such as the body rolling down along a slope, and to expect work safety.

Further, in this device, since the switching valve of the hydraulic circuit can be immediately switched to the closed side only by reducing the pilot pressure on the hydraulic pump side to a predetermined value or less, the pressure oil flowing in the hydraulic pump direction through the hydraulic circuit can be quickly supplied. And it can cut off accurately and stop the rotation of the hydraulic motor instantaneously.
Moreover, the stopped state continues as long as the pilot pressure of a predetermined value is applied to the switching valve from the hydraulic pump side to operate the switching valve to the open circuit side, so that safety accompanying the stop of the aircraft can be secured, It can be a reliable hazard protection device.

Further, in this apparatus, since the emergency control switching valve for opening and closing the pilot circuit on the hydraulic pump side is provided on the handle of the machine body by the operation of the spool, the operator mistakenly moves the handlebar and the rear side of the machine body during the backward traveling of the machine body. When an accident such as getting caught between obstacles occurs, this emergency control switching valve shuts off the pilot circuit by contact with the operator, so the rotation of the hydraulic motor can be instantaneously stopped by braking. It is possible to accurately prevent the occurrence of a serious accident due to the inoperability of such a safety device of this kind or the delay of the rotation stop timing, and it is possible to provide a highly reliable safety device as a countermeasure against this kind of accident.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing one embodiment of an automatic control device according to the present invention.

FIG. 2 is a side view of the machine body showing a mounting position of an emergency control switching valve.

[Explanation of symbols]

1a, 1b: Rollers 2a, 2b: Hydraulic motor 3: Engine 4: Hydraulic pump device 5: Transmission mechanism 6: Swash plate 7: Hydraulic pump 8, 9: Hydraulic circuit 10: Charge pump 13: Shut-off switching valve 14: Flow Path 15: Shutoff path 16: Spring 17: Pilot circuit 18: Emergency control switching valve 19: Connection circuit 20: Handle 21: Spool 22: Flow path 23: Shutoff path

Claims (1)

[Claims] 1. A load roller driven by a hydraulic motor rotated by pressure oil from a hydraulic pump, wherein hydraulic circuits 8 and 9 connect a hydraulic pump 7 and a hydraulic motor 2 to each other.
In addition, a shutoff having a flow passage 14 and a cutoff passage 15 which are opened by pressure oil of a predetermined pressure by the pilot circuit 17 on the hydraulic pump 7 side and are closed when the pressure oil by the pilot circuit 17 drops below a predetermined pressure. An automatic control device for a load roller, comprising a switching valve 13, and an emergency stop switching valve 18 which opens and closes the pilot circuit 17 by operating a protruding spool 21 on a rear handle 20 of the machine body.