JP2604638Y2 - Work vehicle safety devices - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for a working vehicle provided with a working device such as a boom that can be freely raised and lowered.

[0002]

2. Description of the Related Art There is an aerial work vehicle as an example of such a work vehicle. A boom that can be raised and lowered, expanded and contracted, and the like is attached to the body of the aerial work vehicle, and a work table is attached to a tip of the boom. An operator who has boarded the worktable can move to an arbitrary height through the operation of the boom, and can quickly work at the height.
In addition, jacks are attached to four front, rear, left, and right sides of the vehicle body in order to ensure the stability of the vehicle body during such high-place work. The jack has its lower end grounded, and supports the vehicle body against the overturning load acting on the vehicle body in the direction of overturning it.

However, if the operation of the boom is allowed indefinitely just because it is supported by the jack, there is a possibility that the overturning load becomes excessive beyond the limit that can be supported by the jack. For this reason, the work vehicle is provided with a safety device that performs a predetermined alarm operation, for example, controls a further boom operation or activates an alarm buzzer when the overturn load increases to near the limit. In such a safety device, the overturning load is calculated from the operating state of the boom (boom up / down angle / extension amount) and the detected value of the axial force acting on the hydraulic cylinder that drives the boom up and down. There is a load calculation type that performs an alarm operation when the load increases to the maximum allowable load. In addition, the reaction force that mechanically detects that the ground reaction force received by the jack on the opposite side to the boom extension direction has decreased to the minimum allowable reaction force with the increase in the overturning load, and issues an alarm action There are also detection types. Conventional work vehicles have only one of these safety devices.

[0004]

However, in the load calculation type safety device, accurate load calculation is not performed when the detector for detecting the operating state of the boom or the axial force of the hydraulic cylinder is broken or malfunctions. There is a problem that an appropriate alarm operation is not performed. On the other hand, the reaction force detection type safety device is susceptible to vibration of the vehicle body due to the operation of the boom, and does not work as accurately as the load calculation type (that is, to operate the boom closer to the limit). There's a problem.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a safety device for a work vehicle that can perform an alarm operation accurately and reliably.

[0006]

In order to achieve the above object, a safety device according to the present invention comprises a load calculating means for calculating the magnitude of a fall load acting on a vehicle body based on the operating state of a working device. And a reaction force detecting means for detecting that the ground reaction force acting on the jack has decreased to a predetermined minimum allowable reaction force, and in a state where the vehicle body is supported by the jack,
When the overturning load calculated by the load calculating means has increased to the maximum allowable load set according to the support state of the vehicle body by the jack, or the ground reaction force of any jack has been reduced to the minimum allowable reaction force by the reaction force detecting means. When the decrease is detected, an alarm operation (boom operation restriction or alarm buzzer operation) is performed. However, when the jack is used to support the vehicle body, the minimum permissible reaction force required to reduce the ground reaction force of any jack to the minimum permissible reaction force is greater than the maximum permissible load. Is set.

[0007]

As described above, in the safety device according to the present invention,
When the ground reaction force of any jack decreases to the minimum allowable reaction force, the overturning load becomes larger than the maximum allowable load, and conversely, even if the overturning load increases to the maximum allowable load, the ground reaction force of any jack becomes the minimum allowable The setting is such that the value is larger than the reaction force. For this reason, when performing work using the working device while supporting the vehicle body with the jack, normally, when the overturning load reaches the maximum allowable load according to the operating state of the working device (the jack grounding at this time) (The reaction force is a value larger than the minimum allowable reaction force.) The alarm operation is performed, and the fall load is prevented from further increasing, thereby ensuring safety. On the other hand, if the load calculating means is malfunctioning or abnormal, for example, if the sensor for detecting the operating state of the work equipment has failed, the calculation of the overturning load becomes inaccurate, and the actual overturning load becomes maximum. There is a possibility that a warning operation or the like is not performed even if the allowable load is reached. However, in the device according to the present invention, even if the actual overturning load exceeds the maximum allowable load, the alarm is activated when the ground contact force of the jack reaches the minimum allowable reaction force, thereby ensuring safety. You. That is, the alarm operation based on the ground reaction force of the jack serves as a backup for the alarm operation based on the overturning load calculated by the load operation unit, and safety can be ensured even when the load operation unit becomes abnormal. .

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 shows an aerial work vehicle 10 provided with a safety device according to the present invention. At the rear of the vehicle body 11 of the aerial work vehicle 10, a swivel base 12 that can freely perform a horizontal turning operation with respect to the vehicle body 11 is attached. A boom 13 configured to be telescopically extendable and retractable is attached to the upper part of the swivel table 12 so as to be able to move up and down. A work table 14 is horizontally attached to the end of the boom 13, and an operator who gets on the work table 14 can move to an arbitrary height through each operation of the swivel table 12 and the boom 13. In addition, the swivel 12 is the vehicle body 1
The rotary drive is performed by a hydraulic rotary motor (not shown) built in the motor 2. The boom 13 is driven up and down and extended and retracted by a hydraulic up and down cylinder 15 attached between the swivel base 12 and the boom 13 and a hydraulic telescopic cylinder (not shown) built in the boom 13.

Further, the boom 13 is operated to operate the work table 14.
Is moved, the overturning moment (overturning load) B acts in the direction of overturning the vehicle body 11 based on the weight. For this reason, jacks J1 to J4 are attached to the front, rear, left and right of the vehicle body 11 at four places. Hereinafter, the jack attached to the right front of the vehicle body 11 is a right front jack J1, the jack attached to the right rear is a right rear jack J2, the jack attached to the left front is a left front jack J3, and the left is a left jack. The jack attached to the rear is called the left rear jack J4.

As shown in detail in FIG. 2, each of the jacks J1 to J4 is provided with an outer post 21 which is attached to
Inner post 2 which is inserted into the lower part so as to be able to expand and contract
2 and a ground plate 23 attached to the lower end of the inner post 22. Each of the outer post 21 and the inner post 22 has a built-in jack cylinder 24 that is operated by hydraulic pressure. The lower end of the piston rod 24a of the jack cylinder 24 is attached to the lower end of the inner post 22, and the spring receiver 24c is attached to the upper end of the cylinder tube 24b. A coil spring 25 is attached between the spring receiver 24c and the upper surface of the outer post 21 so as to be sandwiched therebetween.

The jacks J1 to J4 constructed as described above
The grounding plate 23 can be raised and lowered by expanding and contracting the inner post 22 with respect to the outer post 21 by the expansion and contraction operation of the jack cylinder 24. Then, after the ground plate 23 is grounded, the jack cylinder 24 is further extended so that the vehicle body 11 can be slightly lifted. In this way, each of the jacks J1 to J4 can support the load of the vehicle body 11 including the overturning moment B (hereinafter, collectively referred to as the vehicle body load) and stabilize the vehicle body 11. In addition, each jack J1-J4 which supported the vehicle body load
Then, according to the variation of the vehicle body load, the coil spring 2
5 is elastically deformed, and the outer post 21 is
And a vertical movement with respect to the jack cylinder 24. Also,
Each of the jacks J1 to J4 supporting the body load receives a reaction force (ground reaction force) having the same magnitude as the body load from the ground.

Next, the safety device according to the present invention will be described. As shown in FIG. 3, the safety device 30 includes a load calculation unit 31, a reaction force detection unit 35, and an alarm unit 40. The alarm unit 40 further includes an alarm controller 4
1, a boom restricting section 42, and a buzzer operating section 45.

As shown in detail in FIG. 4, the load calculating unit 31 includes an elevation angle sensor 32a, an extension amount sensor 32b, a turning angle sensor 32c, an axial force sensor 32d, and a calculator 33.
It is composed of The undulation angle sensor 32a is connected to the boom 13
Is detected with respect to the horizontal level. The extension amount sensor 32b detects the extension amount of the boom 13 with respect to the fully contracted state. The turning angle sensor 32c detects a turning angle of the turning table 12 (boom 13) based on the position directly in front of the vehicle body 11. Further, the axial force sensor 32d is attached to the undulating cylinder 15 that supports the weight of the boom 13, and detects a load acting on the undulating cylinder 15 in the axial direction. The sensors 32a to 32d output detection signals (electric signals) corresponding to the respective detection values. The arithmetic unit 33
Calculates the magnitude of the overturning moment M based on the detection signals from the sensors 32a to 32d, and outputs a signal indicating the calculation result to the alarm controller 41.

The reaction force detector 35 comprises four reaction force detectors 36a to 36d and a power source B, as shown in detail in FIG. Here, each reaction force detector 36a-36d
Are attached to the upper portion of the inner side surface of the outer post 21 in each of the jacks J1 to J4 as shown in FIG. The reaction force detector attached to the right front jack J1 is attached to the right front reaction force detector 36a, the reaction force detector attached to the right rear jack J2 is attached to the right rear reaction force detector 36b, and the left front jack J3. Left front reaction force detector 3
6c and the reaction force detector attached to the left rear jack J4 are referred to as a left rear reaction force detector 36d.

A bar-like cam 37 extending in the vertical direction is attached to the side of the spring receiver 24c at a position facing the reaction force detectors 36a to 36d. The reaction force detectors 36a to 36d are connected to the outer post 21 in response to a change in the ground reaction force (vehicle load) acting on each of the jacks J1 to J4.
At the same time, it moves up and down with respect to the cam 37. That is, the reaction force detectors 36a to 36d move downward when the contact force increases, and move upward when the contact force decreases. When the ground reaction force exceeds the minimum allowable reaction force, the reaction force detectors 36a to 36d detect that the switch lever is set to the cam 37.
And is turned on (closed state in FIG. 4)
become. However, when the ground reaction force is equal to or less than the minimum allowable reaction force, the switch lever is disengaged from the cam 37 and is turned off (opened in FIG. 4).

The four reaction force detectors 36a to 36d configured and operated as described above are connected as shown in FIG.
That is, the right front reaction force detector 36a and the left rear reaction force detector 36d are connected in series to form the first detection line D1. The right rear reaction force detector 36b and the left front reaction force detector 36c are connected in series to form a second detection line D2. The input terminals (the left ends in the figure) of these detection lines D1 and D2 are connected in parallel to the power supply 52. The output terminals (right ends) of these detection lines D1 and D2 are connected to the alarm controller 41.

The alarm controller 41 includes a load calculating unit 31
Is compared with the value of the maximum allowable falling moment stored in advance. If the calculated overturning moment is smaller than the maximum permissible overturning moment on condition that an electric signal (excitation maintaining signal) is input from the output terminal of the reaction force detecting unit 35, As shown in (1), an excitation signal is output to the first excitation signal line S1. Then, the output of the excitation signal is stopped when the calculated overturning moment becomes equal to or more than the maximum allowable overturning moment or when there is no input of the excitation maintaining signal.

As shown in detail in FIG. 5, the boom restricting section 42 is incorporated in a hydraulic supply circuit for supplying hydraulic oil to the boom hydraulic control circuit BC and the jack hydraulic control circuit JC. The boom hydraulic control circuit BC controls the supply of hydraulic oil to the swing motor, the up-and-down cylinder 15, and the telescopic cylinder, and the jack hydraulic control circuit JC.
Controls the supply of hydraulic oil to the jack cylinders 24 and the like of the jacks J1 to J4. The hydraulic supply circuit includes dual pumps P1 and P2. One hydraulic pump (first hydraulic pump) P1 is connected to a first hydraulic line L
1 to supply hydraulic oil to the boom hydraulic control circuit BC. The other second hydraulic pump P2 supplies hydraulic oil to the jack hydraulic control circuit JC via the second hydraulic line L2.

In the middle of the first hydraulic line L1,
An unload valve 43 constituting the boom restricting section 42 is connected via a third hydraulic line L3. When the solenoid 43a is in the excited state, the unload valve 43 is located at the left movement position and closes the third hydraulic line L3. At this time, all hydraulic oil discharged from the first hydraulic pump P1 is supplied to the boom hydraulic control circuit BC. However, when the solenoid 43a is in the non-excited state, the position is switched to the right movement position, and the third hydraulic line L3 is opened to the oil tank T. At this time, the first hydraulic pump P1
The hydraulic oil discharged from is discharged to the tank T without being supplied to the boom hydraulic control circuit BC. Note that the alarm controller 41 is connected to the solenoid 43a via a first excitation signal line S1.

The buzzer operating section 45 includes a relay switch 46 and a buzzer controller 47, as shown in detail in FIG.
And a speaker 48. The second excitation signal line S2 connected to the alarm controller 41 is connected to the relay coil 46a of the relay switch 46. A switch 46b of the relay switch 46 is connected to a power line S3 connecting the power source B and the buzzer controller 47.
Mounted on top. In the relay switch 46, when the relay coil 46a is in the excited state, the switch 46b is in the open state, and cuts off the power supply line S3. On the other hand, when the relay coil 46a is in the non-excited state, the switch 46b is in the closed state and the power supply line S3
Is opened.

The buzzer controller 47 outputs an alarm signal when receiving power from the power supply B via the power supply line S3. The speaker 48 operates upon receiving the alarm signal, and generates an alarm sound.

Next, the safety device 3 configured as described above
The operation of 0 will be described. Here, as an example, FIG.
As shown in FIG.
In the state where the boom 13 is turned leftward (downward in the figure), the boom 13 is operated to fall from the upright state or to extend from the contracted state. In this case, the load on the vehicle body is the left rear jack J4 and the left front jack J3 on the side where the boom 13 extends.
And the right front jack J1 on the other side
And the body load remaining in the right rear jack J2 decreases. In particular, the decrease in the body load of the right front jack J1 is remarkable. The ground reaction force acting on each of the jacks J1 to J4 increases and decreases in accordance with the vehicle body load supported by each of the jacks J1 to J4. At this time, there is a possibility that the vehicle body 11 will fall around the fallover branch line T1 connecting the grounding plates 23 of the left front jack J3 and the left rear jack J4. The load calculating unit 31 calculates the overturning moment that increases with the tilting / extending operation of the boom 13 based on the turning angle, the tilt angle / extension amount of the boom 13 and the axial force of the tilting cylinder 15.

On the other hand, in the process of increasing the overturning moment, the ground reaction force of the right front jack J1 falls below the minimum allowable reaction force, the right front reaction force detector 36a is opened, and the first detection line D1 is cut off. Even right rear jack J
As long as the ground reaction force of the second exceeds the minimum allowable reaction force, the second detection line D2 is in the open state, so that the excitation maintaining signal is continuously input to the alarm controller 41. Therefore,
The output of the excitation signal from the alarm controller 41 to the solenoid 43a of the unload valve 43 is also continued. On the other hand, the excitation signal is also continuously input to the relay coil 46a of the relay switch 46.

When the calculated falling moment increases to the maximum allowable falling moment, the alarm controller 41
The output of the excitation signal from the
3 switches from the left movement position to the right movement position. This allows
Further tilting / extending operations of the boom 13, that is, operations in a direction in which the overturning moment increases, are restricted. Thus, the stability of the vehicle body 11 is ensured. When the calculated overturning moment reaches the maximum allowable overturning moment, the ground reaction force of the right rear jack J2 still exceeds the minimum allowable reaction force.

However, the sensor 3 in the load calculator 31
If any one of 2a to 32d breaks down or the wiring connecting each sensor and the computing unit 33 is broken, the computing unit 33 cannot calculate an accurate overturning moment, and the actual overturning moment becomes an allowable overturning. The operation of the boom 13 may not be restricted even when the moment is reached. In such a case, at the stage where the overturning moment exceeds the maximum allowable overturning moment, the ground reaction force acting on the right rear jack J2 decreases below the minimum allowable reaction force, and the right rear reaction force detector 36b
Becomes open. As a result, the second detection line D2 is also cut off together with the first detection line D1 that was cut off earlier, and the excitation maintaining signal is not input to the alarm controller 41. Therefore, the alarm controller 4
The output of the excitation signal from 1 stops and the unload valve 4
3 is switched to the right movement position, and the further boom 13 is lowered and extended. Thus, the load calculation unit 31
Although the stability of the vehicle body 11 is slightly lower than when the operation of the boom 13 is restricted through the above, the accident of the vehicle body 11 falling over is surely prevented.

At the same time, no excitation signal is input to the relay coil 46a and the switch 46b is closed, so that an electric signal is input to the buzzer controller 47 from the power supply B. Therefore, an alarm sound is generated from the speaker 48. Thus, the operator can clearly determine that any of the sensors 32a to 32d of the load calculation unit 31 has an abnormality.

As shown in FIG. 6, when the boom 13 is turned rearward, there is a possibility that the boom 13 will fall around the falling branch line T2 connecting the right rear jack J2 and the left rear jack J4. Also in this case, the sensor 32 of the load calculation unit 31
Although the operation of the boom 13 is regulated as long as the a to 32d are normal, when the sensors 32a to 32d become abnormal, the ground reaction force acting on the right front jack J1 and the left front jack J3 is minimized. At the stage when the reaction force is reduced to the allowable reaction force or less, the operation of the boom 13 is restricted through the reaction force detection unit 35 and an alarm is issued by a buzzer.

In the above embodiment, the safety device attached to the aerial work vehicle has been described. However, the safety device according to the present invention is not limited to this. Can be adopted.

[0029]

[Effects of the Invention] As described above, the safety device according to the present invention can be used when the work is performed using the working device while supporting the vehicle body with a jack. In response to this, an alarm is activated when the overturning load reaches the maximum allowable load, and the overturning load is prevented from further increasing, thereby ensuring safety. On the other hand, if the load calculation means malfunctions or becomes abnormal, an alarm will be activated when the ground contact force of the jack reaches the minimum allowable reaction force, even if the actual overturning load exceeds the maximum allowable load. Is performed to ensure safety. That is, the alarm operation based on the ground reaction force of the jack serves as a backup for the alarm operation based on the overturning load calculated by the load operation unit, and safety can be ensured even when the load operation unit becomes abnormal. .

[Brief description of the drawings]

FIG. 1 is a side view of an aerial work vehicle equipped with a safety device according to the present invention.

FIG. 2 is a sectional view of a jack of the aerial work vehicle.

FIG. 3 is a block diagram of the safety device.

FIG. 4 is a partial configuration diagram of the safety device.

FIG. 5 is a partial configuration diagram of the safety device.

FIG. 6 is an operation explanatory view of the safety device.

[Explanation of symbols]

 Reference Signs List 10 aerial work vehicle 13 boom J1 to J4 jack 30 safety device 43 unload valve 36a to 36d reaction force detector T1, T2 fall down branch line

Claims (1)

(57) [Scope of request for utility model registration] 1. A safety device for a working vehicle having a working device on a vehicle body, and a jack for supporting the vehicle body with its lower end grounded on the front, rear, left and right sides of the vehicle body, and A load calculating means for calculating the magnitude of the overturning load acting in the direction of overturning the vehicle body based on an operation state and the like; and a detecting means for detecting that the ground reaction force acting on the jack has decreased to the minimum allowable reaction force. Force detection means, and in a state where the vehicle body is supported by the jack,
When the overturning load calculated by the load calculating means has increased to the maximum allowable load set according to the support state of the jack, or when the ground reaction force of any of the jacks is reduced by the reaction force detecting means to the minimum allowable reaction And a warning means for performing a warning operation when it is detected that the force has been reduced, and in a state where the vehicle body is supported by the jack,
The minimum allowable reaction force is set so that the overturning load acting on the vehicle body required to reduce any of the jacking reaction forces of the jack to the minimum allowable reaction force is greater than the maximum allowable load. A safety device for a work vehicle, wherein the safety device is provided.