JPS6361233B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a self-propelled crane used for crane work.

Among these types of self-propelled cranes, there is a so-called wheel crane that is equipped with a dual-purpose driver's seat for traveling and operating the crane work.This wheel crane is equipped with a crane device and the dual-purpose driver's seat on the swivel platform of the traveling vehicle body. It is configured with. In addition, some wheel cranes are configured so that both the front wheels and rear wheels of the traveling vehicle body can be steered by steering cylinders, and these wheels can be selected from the dual-purpose driver's seat. It's summery.
By the way, when a wheel crane such as this, in which the steering wheel can be selected between only the front wheels and the front and rear wheels at the same time, steers only with the front wheels, it is necessary to securely lock and disable the steering of the rear wheels. . For this reason, conventionally, the steering of the rear wheels can be locked by manually inserting a lock lever or the like into the rear wheels to prevent the steering cylinder from expanding or contracting. However, in this wheel crane, the selection operation of the steering wheels and the operation of the rear wheels were performed separately and independently, so when switching the steering wheels from only the front wheels to the front and rear wheels, the lock lever is There are times when I forget to release the pull-out lock, that is, the rear wheel steering lock. In such a case, the rear wheel steering cylinder may operate even though the rear wheel steering is locked, resulting in damage to the steering cylinder, lock lever, etc. .

This invention was made based on the above-mentioned circumstances, and its purpose is that when switching the steering wheel from only the front wheels to the front and rear wheels, the above-mentioned switching must be performed after the steering lock of the rear wheels is released. To provide a self-propelled crane that can prevent damage to a steering cylinder of a rear wheel, etc.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 shows a wheel crane among self-propelled cranes, and numeral 1 in the figure is the running body of the wheel crane. This traveling vehicle body 1 includes front wheels 2, 2 and rear wheels 3, 3, and the rear wheels 3, 3 are rotationally driven by an engine 5 in an engine room 4. In addition, a boom 7 is mounted on the swivel base 6 on the traveling vehicle body 1.
A crane device 8 and a dual-purpose driver's seat 9 are provided, and the dual-purpose driver's seat 9 operates the crane device 8 and also steers the traveling vehicle body 1.

The steering of the traveling vehicle body 1 is performed by a hydraulic circuit 10 shown in FIG. This hydraulic circuit 10 includes front wheel steering cylinders 11, 11 and rear wheel steering cylinders 12, 12 for steering the front wheels 2, 2 and rear wheels 3, 3, and a hydraulic tank 1 as a pressure oil source.
3. A hydraulic pump 14 is provided, and this hydraulic tank 13
and each of the above-mentioned steering cylinders 11, 11, 12, 12 through steering hydraulic pressure pipes 15a, 15b, 15c, 15.
between steering hydraulic pipes 15d, 15f and 15g, 15h, which are connected by d, 15e, 15f, 15g, 15h, and connect between front wheel steering cylinders 11, 11 and rear wheel steering cylinders 12, 12; An electromagnetic steering switching valve 16 is provided in the steering wheel.
Further, 17 is a steering unit, and 18 is a steering handle arranged in the dual-purpose driver's seat 9 and used to operate the steering unit 17. Note that 19 is a rotary joint provided between the traveling vehicle body 1 and the dual-purpose driver's seat 9.

20 is a hydraulic circuit for a rear wheel locking mechanism 21 shown in FIGS. 3 and 4 that locks and disables steering of the rear wheels 3, 3. This hydraulic circuit 20
is equipped with a double-rod type lock cylinder 22 that locks the steering of the rear wheels 3, and a hydraulic pipe line 23a, 23 that locks the lock cylinder 22 and the hydraulic tank 13.
b, 23c, and 23d, lock hydraulic line 2
An electromagnetic rear wheel lock switching valve 24 is provided between 3a, 23b and 23c, 23d.

The rear wheel lock mechanism 21 provided with the lock cylinder 22 will now be described with reference to FIGS. 3 and 4. For example, a lock arm 25 is disposed near the rear wheel steering cylinder 12 shown in FIG.
One end is rotatably supported via a pivot 26 in the same way as the rod tip of the rear wheel steering cylinder 12, and the other end is connected to the rear wheel steering cylinder within a bracket 28 attached to the rear axle 27. 12 is configured to be slidable as it expands and contracts. The lock cylinder 22 is attached to the bracket 2.
It is arranged vertically on 8. A lock pin 2 is attached to the tip of the lower rod 22a of this lock cylinder 22.
9 is provided, and this lock pin 29 fits into a fitting hole 30 formed in the lock arm 25 and prevents the lock arm 25 from sliding, thereby locking and disabling the steering of the rear wheel 3. It's becoming like that. Note that 31, 31 are guide rollers that guide the sliding movement of the lock arm 25.

The steering switching valve 16 and the rear wheel lock switching valve 24 of the hydraulic circuits 10 and 20 are connected to a second
They are controlled by operating electrical circuits 32 and lock path circuits 33, respectively, shown in the figure. First, the operation electric circuit 32 connects the power source A and the steering switching valve 16 through a steering electrical circuit 34, and the steering electrical circuit 34 is provided with a steering wheel selection switch 35 that controls the supply of electricity to the steering switching valve 16. It is composed of Further, a steering direction changeover switch 36 is provided between the steering wheel selection switch 35 and the steering changeover valve 16 to change over the steering direction of the rear wheels 3, 3. This steering direction changeover switch 36 is composed of a bipolar contact switch, and therefore, the contact c of the steering direction changeover switch 36 and the solenoid 16 of one of the steering direction changeover valves 16
c refers to the branch circuit 34c that constitutes the steering circuit 34.
and the contact g and the other solenoid 1
6g is connected by a branch circuit 34g that also constitutes the steering circuit 34. Further, the lock energizing circuit 33 connects the power supply A and the rear wheel lock switching valve 24 through a lock electric line 37.
A rear wheel lock changeover switch 38 is provided at the rear wheel lock switch 38. This lock line 37 is branched from the steering line 34 between the power source A and the steering wheel selection switch 35. Further, the lock circuit 37 is provided with a bipolar contact relay 39. Therefore, the lock line 37 is connected to the coil 39a of the relay 39, and the contact p of the relay 39 is directly connected to the power source A side through the relay line 37p. The contact q of the relay 39 is connected to one solenoid 24q of the rear wheel lock switching valve 24 through a branch circuit 37q that constitutes the lock circuit 37, and the contact r is connected to the other solenoid 24r. It is connected by an electric line 37r. Also,
A steering wheel selection switch 35, a rear wheel lock switching switch 38, and a steering direction switching switch 36 are arranged in the dual-purpose driver's seat 9. In addition, the distribution line 37
q and 37r are provided with limit switches 40 and 41, respectively, for checking the operating state of the lock pin 29 of the lock cylinder 22, and
A limit switch 42 is provided to confirm alignment between the lock pin 29 and the fitting hole 30. The limit switches 40, 41 are, for example, normally closed switches, and as specifically shown in FIG. 4, a contact piece 44 attached to the upper rod 22b of the lock cylinder 22
When the two come into contact with each other, the opening becomes "open." The limit switch 42 is a normally open switch, and for example, the limit switch 42 is mounted on the bracket 28 side and a contact is provided on the lock arm 25 side.
When the lock pin 29 and the fitting hole 30 are aligned, these contacts come into contact with the limit switch 42, and the limit switch 42 is closed.

A confirmation relay 45 is provided between the steering wheel selection switch 35, the rear wheel lock changeover switch 38, and the steering direction changeover switch 36. That is, the coil 45 of this confirmation relay 45
A is connected to the lock circuit 37 between the rear wheel lock changeover switch 38 and the relay 39 through a control circuit 46, and the confirmation relay 45 is activated only when the rear wheel lock changeover switch 38 is closed.
The steering electric circuit 34 is closed by closing the contact s of the rear wheel lock switch 38, and the steering electric circuit 34 is opened when the rear wheel lock changeover switch 38 is opened.
Note that 47 is a rotary brush provided between the traveling vehicle body 1 and the dual-purpose driver's seat 9.

Next, the operation of an embodiment with such a configuration will be explained. First, normal steering using only the front wheels 2, 2 will be explained. In this case, the steering wheel selection switch 35 and the rear wheel locking switch 38 are in the "open" position.
The steering control valve 16 is in the neutral position. Therefore, oil is supplied from the hydraulic tank 13 only to the front wheel steering cylinders 11, 11, and the steering unit 1 is operated by operating the steering handle 18.
The front wheels 11, 11 can be steered by switching the oil supply to either one of the steering hydraulic pressure lines 15c, 15d at step 7. When steering is performed using only the front wheels 11, 11, the solenoid 24g of the rear wheel lock switching valve 24 is energized from the power source A via the relay circuit 37p and the relay 39 branch circuit 37q. can be switched. Therefore, oil is sent from the hydraulic tank 13 to the lock cylinder 22 through the lock hydraulic pipes 23a and 23d, and the lower rod 2 of this lock cylinder 22 is supplied with oil.
2a is extended, the lock pin 29 is fitted into the fitting hole 30 of the lock arm 25, and the steering of the rear wheels 3, 3 is locked. Then, when the steering of the rear wheels 3, 3 is locked, the contact piece 44 of the lock cylinder 22
comes into contact with one (lower) limit switch 40 and this limit switch 40 becomes "open", thus opening the current distribution path 37q and stopping the power supply to the rear wheel lock switching valve 24. Therefore, the rear wheel lock switching valve 24 returns to the neutral state, oil supply to the lock cylinder 22 is stopped, and the lock pin 29 is held in the fitting hole 30.

When switching from such steering of only the front wheels 2, 2 to simultaneous steering of the front wheels 2, 2 and rear wheels 3, 3, the rear wheel lock changeover switch 38 is turned on and set to "closed". . This energizes the coil 39a of the relay 39, switching the relay 39 from the contact q to the contact r, and energizes the solenoid 24r of the rear wheel lock switching valve 24 from the power supply A through the distribution path 37r, and thus the rear wheel The lock switching valve 24 is switched. Therefore, the oil is sent from the hydraulic tank 13 to the lock cylinder 22 via the lock oil pressure pipes 23a and 23c, and the lower rod 22a of the lock cylinder 22 is contracted to pull out the lock pin 29 from the fitting hole 30, thereby locking the lock arm 25. This enables sliding of the rear wheels 3, 3, or steering of the rear wheels 3, 3. Then, when the lock pin 29 is pulled out from the fitting hole 30, the contact piece 44 comes into contact with the other (upper) limit switch 41, and this limit switch 41
is "open", and the branch circuit 37r is therefore opened, and the energization to the rear wheel lock valve 24 is stopped. Therefore, this rear wheel lock switching valve 24
returns to the neutral state, oil supply to the lock cylinder 22 is stopped, and the lock pin 29 is held in a state where it is pulled out from the fitting hole 30. Then, the steering wheel selection switch 35 is turned on to "close". At this time, since the rear wheel lock changeover switch 38 is in the "closed" state, the coil 4 of the confirmation relay 45
5a is energized, and the contact s of this confirmation relay 45
is closed, and the steering electric circuit 34 and the branch circuit 34c (or the distribution circuit 34g) are closed. Therefore, power source A
The solenoid of the steering switching valve 16 is energized to switch the steering switching valve 16, and the oil sent from the hydraulic tank 13 is transferred to the front wheel steering cylinders 11, 11.
Only the front wheel steering cylinders 11, 11 and the rear wheel steering cylinders 12, 12 are operated, and the front wheels 2, 2 as well as the rear wheels 3, 3 are steered. When the contact point c of the steering direction changeover switch 36 is closed, the solenoid 16c of the steering changeover valve 16 is energized, so that when steering is performed via the steering unit 17, the front wheel steering Cylinder 11, 11
In other words, the direction of expansion and contraction of the rear wheel steering cylinders 12, 12 is reversed, that is, the steering of the front wheels 2, 2 and the rear wheels 3, 3 is reversed, resulting in so-called counter running. g is closed, the solenoid 16g of the steering switching valve 16 is energized, so the front wheel steering cylinders 11, 1
1 and the rear wheel cylinders 12, 12 are in the same direction of expansion and contraction, that is, the front wheels 2, 2 and the rear wheels 3, 3 are in the same steering direction, resulting in so-called grab running.

Therefore, according to such an embodiment, when the rear wheel lock changeover switch 38 is in the "open" position, that is, when the steering of the rear wheels 3, 3 is locked, the confirmation relay is activated. 45 coils 45a
Since the power is not supplied to the steering electric line 34 (branch electric lines 34c, 3
4g) has been developed. For this reason, even if the steering wheel selection switch 35 is turned on and "closed" to switch the steering wheels from only the front wheels 2, 2 to the front wheels 2, 2 and the rear wheels 3, 3, the steering wheel selection switch 35 is closed. is not energized, and the steering switching valve 16 is not switched. Therefore, when the steering of the rear wheels 3, 3 is locked, the rear wheel steering cylinders 12, 1
As a result, the rear wheel steering cylinders 12, 12, the lock cylinder 22, etc., and the rear wheel locking mechanism 21 are not damaged. Further, according to this embodiment, the lock cylinder 22 is provided with limit switches 40 and 41 for checking the operating state of the lock pin 29.
These confirmation limit switches 40 and 41 can automatically control switching of the rear wheel lock switching valve 24. Additionally, a limit switch 42 is provided to check the alignment between the lock pin 29 and the lock arm 25 fitting hole 30, so if these alignments are not made, the rear wheel lock switching valve 24 will not switch, and the rear wheel This allows the reliability of the lock mechanism 21 to be further improved. Further, since the rear wheel locking mechanism 21 can be operated from within the dual-purpose driver's seat 9, it is possible to easily change the steering wheel of the wheel crane.

Note that the present invention is not limited to the above embodiment. For example, the electric circuit indicated by C in FIG. 2 is not necessarily limited to the above configuration, but may be an electric circuit B having the configuration shown in FIG. 5. This electric circuit B is provided with a steering direction changeover switch 50 which is a bipolar contact switch with a neutral point and serves as both a steering wheel selection switch and a steering direction changeover switch, and this steering direction changeover switch 50 selects the steering wheel. This makes it possible to switch the steering direction of the rear wheels. Further, in this case, the confirmation relay 45 is provided between the steering direction changeover switch 50 and the rear wheel lock changeover switch 38.

Note that the lock cylinder of the present invention is not limited to a hydraulic type, but may be a pneumatic type, so the pressure source may be a compressor or the like, and the pipe line may be a pneumatic line. good.

As explained above, the present invention prevents the steering electric circuit connecting the steering direction changeover switch and the steering direction changeover valve from being closed until after the steering lock of the rear wheels is released. It is characterized by making it impossible to select the steering wheel using the direction changeover switch.
Therefore, when the rear wheel steering is locked, the rear wheel steering cylinder does not operate, so the rear wheel steering cylinder and the lock cylinder are not damaged. The effect is great.

[Brief explanation of drawings]

1 to 4 show an embodiment of the present invention, in which FIG. 1 is a side view of a wheel crane, FIG. 2 is a circuit diagram showing a hydraulic circuit and an electric circuit for steering the wheel crane, and FIG. 4 is a sectional view taken along the line -- in FIG. 3, and FIG. 5 is an electric circuit diagram for steering a wheel crane showing another embodiment. 11, 12... Steering cylinder (front wheel, rear wheel),
22... Lock cylinder, 16... Steering switching valve, 24... Rear wheel lock switching valve, 35... Steering wheel selection switch, 36, 50... Steering direction switching switch, 38... Rear wheel lock switching Switch.

Claims (1)

[Claims] 1 A system installed in each steering cylinder that steers the front wheels and rear wheels, and in a steering hydraulic line connecting these steering cylinders and a pressure oil source to switch the oil supply from this pressure oil source to each steering cylinder. An electromagnetic steering switching valve that controls the steering of only the front wheels or both the front and rear wheels, and an operating electric circuit that connects this steering switching valve and a power source to control the energization of the steering switching valve. A steering direction changeover switch that selects the steering wheel by switching between only the front wheels and both the front and rear wheels; a lock cylinder that locks the steering of the rear wheels when steering only with the front wheels; An electromagnetic rear wheel lock switching valve is installed in a lock hydraulic line connecting the cylinder and a pressure oil source, and controls the operation of the lock cylinder by switching the oil supply from the pressure oil source to the lock cylinder. A rear wheel lock changeover switch is provided in the lock energization circuit connecting the lock changeover valve and the power supply and controls the energization to the rear wheel lock changeover valve.The rear wheel lock changeover switch is operated to lock the rear wheels. When the rear wheels are locked, the operating electric circuit is closed and the steering wheel can be selected using the steering direction changeover switch. Conversely, when the rear wheels are locked, the operating electric circuit is opened and the steering direction switch is unlocked. A self-propelled crane characterized in that steering wheels cannot be selected using a steering direction switch.