JPH0774509B2 - Safety device for solenoid valve controlled work machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a safety device for a solenoid valve control type working machine such as a backhoe.

(Prior Art) In a backhoe, a rocking base that supports a boom is provided by a rocking cylinder (hydraulic cylinder) so as to be rockable left and right, and a rocking cylinder and a rocking cylinder are controlled by a control signal from a control unit. A solenoid valve control type in which a detector for detecting the swing position of the moving base is provided, and feedback control or the like is performed so as to stop the swing base at the target position while detecting the swing position of the swing base. There is.

In the case of adopting such a control system, if an abnormality occurs in the electric system, the control becomes impossible and there is a risk of causing an accident. Therefore, a self-diagnosis device for short circuit or disconnection has been conventionally provided.

However, conventionally, no measures have been taken against the abnormality on the spool side of the solenoid valve.

(Problems to be Solved by the Invention) Conventionally, if an abnormality such as clogging of the spool of the solenoid valve occurs, the rocking cylinder operates independently of the control system, causing a runaway operation.

In view of such a point, the present invention forcibly shuts off the hydraulic circuit and locks the working machine inoperable if the working machine is operating despite the stop signal being input to the solenoid valve. It is something that is done.

(Means for Solving the Problems) As means for solving the problems, the present invention provides hydraulic cylinders 22 and 23 for operating the working machine 12 and a solenoid valve 28 for controlling the hydraulic cylinders 22 and 23 by a control signal from the control unit 42. And the working machine 12
In a solenoid valve control type working machine provided with a detector 24 for detecting the operation of the solenoid valve, a shutoff solenoid valve 33 is provided in series with the solenoid valve 28 in the hydraulic circuit 32 of the hydraulic cylinders 22, 23, and the control unit 42 controls the solenoid valve 28
A shutoff control unit that outputs a shutoff signal to the shutoff solenoid valve 33 and outputs a shutoff signal to the shutoff solenoid valve 33 when the detector 24 detects the operation of the work implement 12
48 is provided.

(Operation) If the solenoid valve 28 remains open despite the stop signal being input from the control unit 42 to the solenoid valve 28, the working machine 12 operates and the detector 24 detects the operation. So the shutoff control unit
48 outputs a cutoff signal, and the cutoff solenoid valve 33 cuts off the hydraulic circuit 32. Therefore, the work implement 12 is locked inoperable.

(Example) Hereinafter, the present invention will be described in detail with reference to the illustrated example.
In the figure, 1 is a tractor vehicle body, 2 is a front wheel, and 3 is a rear wheel. 4 is a steering wheel and 5 is a driver's seat.

Reference numeral 6 denotes a front loader mounted on the front portion of the tractor vehicle body 1. The masts 7 are attached to the left and right sides of the tractor vehicle body 1, a boom 8 pivotally attached to the upper end of the mast 7 so as to be vertically movable, and a boom. It has a boom cylinder 9 for moving up and down 8, a bucket 10 rotatably attached to the tip of the boom 8, and a bucket cylinder 11 for rotating the bucket 10.

Reference numeral 12 denotes a backhoe (working machine) mounted on the rear end portion of the tractor body 1, and a machine frame 13 attached to the tractor body 1 and a machine frame 13 pivotally attached to the machine frame 13 about a vertical axis 14 so as to be swingable. Swing base 15 and a boom 16 pivotally attached to the swing base 15 so as to be vertically movable.
And an arm 17 pivotally attached to the tip of the boom 16
And a bucket 18 pivotally attached to the tip of the arm 17
And a control box 19 and a driver's seat 20 provided on the swing base 15. As shown in FIG. 5, the rocking platform 15 is supported by a pair of upper and lower brackets 21 projecting rearward from the machine frame 13 via a vertical axis 14, and in the vicinity of the lower bracket 21, the machine frame 13 and the rocking platform 15 are supported. A pair of left and right rocking cylinders (hydraulic cylinders) 22 and 23 interposed between and are operated to rock.
The swing base 15 is attached with a potentiometer-type swing detector 24 for detecting the swing position of the swing base 15. boom
The boom cylinder 25 allows vertical movement of the arm 16, the arm cylinder 26 allows the arm 17 to bend, and the bucket cylinder 27 allows the bucket 18 to rotate.

As shown in FIG. 2, the swing cylinders 22 and 23 are electromagnetic valves 28, the boom cylinder 25 is a boom control valve 29, the arm cylinder 26 is an arm control valve 30, and the bucket cylinder 27 is a bucket control valve.
Each of the hydraulic circuits 32 is configured to be controlled by 31 and a shutoff solenoid valve 33 is provided in series with the solenoid valve 28 on the hydraulic pump side of the solenoid circuit 28 including them.

The shutoff solenoid valve 33 is of a two-position type and is normally in an open state. When the solenoid 34 is excited, the shutoff solenoid valve 33 is switched to a closed state to shut off the hydraulic circuit 32. In addition, 35,3
6 is a stabilizer control valve.

On the upper surface side of the control box 19, as shown in FIG. 6, two operation levers 37 and 38 which are slidable in the front-rear direction and the left-right direction are provided side by side. When the operating lever 37 is operated left and right, the swing base 15 swings left and right via the solenoid valve 28, and when operated forward and backward, the boom 16 moves up and down via the boom control valve 29. When the operating lever 38 is operated left and right, the bucket 18 is squeezed and dumped via the bucket control valve 31, and when operated forward and backward, the arm 17 is expanded and contracted via the arm control valve 30.

FIG. 1 shows a control system, and reference numeral 40 is a potentiometer for swing command, which is configured to interlock with the operation of the operating lever 37 in the left-right direction. A control unit 42 controls the solenoid valve 28, and includes a direction determination unit 43 that determines the swinging direction based on a command signal from the potentiometer 40, and a speed signal generation unit 44 that generates a speed signal proportional to the command signal. . Reference numeral 45 denotes a sample and hold unit, which stores a signal from the detector 24 as a target stop position when the switch 46 is pressed. 47
Is a comparison unit for automatic stop.
The present position of the oscillating table detected by the detector 24 is compared with the stop target position from the sample hold unit 45, and a stop signal is output from the control unit 42 when they match. Reference numeral 48 is a shutoff control unit for controlling the shutoff solenoid valve 33.
44 outputs a stop signal to the solenoid valve 28 and the detector 24
When the swing of 15 is detected, a shutoff signal is output to excite the solenoid 34 of the shutoff solenoid valve 33. Reference numeral 49 is a buzzer / lamp alarm unit, which is configured to be activated and alarm when the shutoff control unit 48 outputs a shutoff signal. The control unit 42, the sample hold unit 45, the comparison unit
The 47, the shutoff control unit 48, and the like are configured by a microcomputer.

In the above structure, when excavating a groove or the like, first, the swing base 15 is swung to stop so that the bucket 18 is located at the excavation position, and then the switch 46 is pushed. Then, the rocking table at that time
Since the detector 24 detects the swing position of 15, the signal is stored in the sample hold unit 45 as the stop target position.

Use the operation lever to remove the soil from the bucket 18 to the side.
When 37 is tilted to the left or right, the solenoid valve 28 opens and the rocking cylinders 22 and 23 expand and contract.
It swings in the tilting direction of 7 at a rocking speed proportional to the tilting angle. Then, when the operation lever 37 is returned to the neutral position at an appropriate earth discharging position, the solenoid valve 28 is closed by the stop signal from the control unit 42 and the swing cylinders 22 and 23 and the swing base 15 are stopped. To soil.

After this earth removal, the rocking base 15 is rocked in the opposite direction, and the bucket 18
The oscillating base 15 is returned to the stop target position and automatically stopped so as to reach a predetermined excavation position. In this case, when the operation lever 37 is tilted in the opposite direction, the rocking base 15 starts rocking toward the stop target position at a speed proportional to the tilt angle. On the other hand, the detector 24 detects the current swing position of the swing base 15, and the comparison unit 47 compares it with the stop target position. Since the stop signal is output to 28, the solenoid valve 28 is closed and the rocking base 15 automatically stops at the stop target position.

During such control, the safety check subroutine checks the solenoid valve 28 for abnormalities at regular sampling intervals. That is, as shown in FIG. 3, the shutoff solenoid valve
It is determined whether 33 is on (excitation) (step), and if the shutoff solenoid valve 33 is off, it is determined whether an open signal is given to the solenoid valve 28 (step). Then, if an open signal is given to the solenoid valve 28, it is reset. On the contrary, if the stop signal is given to the solenoid valve 28, the detection signal of the detector 24 is input (step) and compared with the data at the previous sampling (step) to see if the rocking base 15 is rocking. It is determined whether or not (step). That is, if the spool of the solenoid valve 28 is clogged with dust or the like, the oscillating base 15 oscillates and the detection signal of the detector 24 changes, so this is determined in step. If the swing table 15 is swinging, a shutoff signal is given to the shutoff solenoid valve 33 to excite the solenoid 34 to close the shutoff solenoid valve 33 (step). Therefore, since the hydraulic circuit 32 is shut off, even if the solenoid valve 28 remains open, the entire backhoe 12 becomes inoperable and the runaway operation does not occur. Then, the alarm unit 49 warns the operator (step).

In addition, although the backhoe 12 is illustrated in the embodiment,
A solenoid valve control type working machine can be similarly implemented.

According to the present invention, the hydraulic circuit 32 of the hydraulic cylinders 22 and 23,
A shutoff solenoid valve 33 is provided in series with the solenoid valve 28, and when the control unit 42 outputs a stop signal to the solenoid valve 28 and the detector 24 detects the operation of the work machine 12, the shutoff solenoid valve 33 is provided with a shutoff signal. Since the control unit 48 is provided, even if the solenoid valve 28 remains open due to dust or the like, the working machine 12 does not run away and the safety is significantly improved.

[Brief description of drawings]

The drawings show one embodiment of the present invention. Fig. 1 is a block diagram of a control system, Fig. 2 is a hydraulic circuit diagram, Fig. 3 is an operation flowchart, Fig. 4 is a side view of the whole, and Fig. 5 is an oscillation diagram. FIG. 6 is a cross-sectional plan view of the moving base, and FIG. 6 is a layout view of the operation lever. 12 ... back hoe (working machine), 15 ... oscillating platform, 22,23 ... oscillating cylinder (hydraulic cylinder), 24 ... detector, 28 ... solenoid valve,
32 ... Hydraulic circuit, 33 ... Shut-off solenoid valve, 42 ... Control section, 48 ... Shut-off control section.

Claims (1)

[Claims] A hydraulic cylinder (22) (23) for operating a work machine (12), and a solenoid valve (28) for controlling the hydraulic cylinder (22) (23) by a control signal from a control section (42). A hydraulic cylinder (22) (23) in a solenoid valve control type working machine equipped with a detector (24) for detecting the operation of the working machine (12)
The hydraulic circuit (32) is provided with a shutoff solenoid valve (33) in series with the solenoid valve (28), the control unit (42) outputs a stop signal to the solenoid valve (28), and the detector (24) operates. A safety device for a solenoid valve control type working machine, comprising a shutoff control section (48) for giving a shutoff signal to a shutoff solenoid valve (33) when the operation of the machine (12) is detected.