JP2976328B2 - Boom device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boom device, and more particularly to a boom device having an auxiliary cylinder for preventing liquid leakage.

[0002]

2. Description of the Related Art A concrete pump truck equipped with a boom device is used to perform concrete placing work over a wide range. In a concrete pump truck equipped with a boom device, there is a problem that the boom vibrates greatly due to pulsation or the like accompanying the delivery of concrete. In order to solve such a problem, a fluid transport boom device provided with a drive control means for suppressing vibration of the boom has been proposed (JP-A-7-217212).

FIG. 6 shows the structure of such a drive control means 2. When changing the position of the boom (not shown)
The stroke x of the cylinder 6 is changed by controlling the solenoid valve 4 and changing the pressure of the cylinder 6 provided on the boom. By changing the stroke x, the boom angle is set to a desired angle. When the change of the posture of the boom is completed, the solenoid valve 4 is closed.

In order to provide the cylinder 6 with a spring action and a damper action, a pressure-intensifying cylinder 8 is provided in addition to the cylinder 6. When no vibration is applied to the boom, the piston 8a of the pressure-intensifying cylinder 8 stands by at an intermediate position (neutral position) of the pressure-intensifying cylinder 8. When vibration is applied to the boom, the stroke x of the cylinder 6 changes, and accordingly, the stroke of the pressure-intensifying cylinder 8 also changes.

The CPU 12 determines a stroke x of the cylinder 6 based on the stroke of the pressure-intensifying cylinder 8 taken in through the position sensor 10, performs a predetermined calculation based on the stroke x, and obtains a target pressure of the cylinder 6. F is calculated, and the target pressure F is output to the servo amplifier 14.

[0006] The servo amplifier 14 gives an output corresponding to the difference between the target pressure and the current pressure of the cylinder 6 detected by the pressure sensor 16 to the electromagnetic servo valve 18 and changes the pressure of the cylinder 6 to the target pressure F. Control to match. That is, if the target pressure F is smaller than the pressure of the cylinder 6, the oil is discharged into the oil tank 20 and the cylinder 6
If the target pressure F is higher than the pressure, the control is performed so that oil is supplied from the oil tank 20.

[0007] By controlling the pressure of the cylinder 6 in this manner, the cylinder 6 has a spring action and a damper action, and the vibration of the boom during the concrete placing operation can be suppressed. Further, the electromagnetic servo valve 18
If an abnormality occurs in the control of the
Stay within the stroke range. That is, there is no possibility that the boom will operate abnormally over a wide range.

[0008]

However, the conventional fluid transport boom device as described above has the following problems. When the boom is retracted after the concrete placing operation is completed, no vibration is applied to the boom, so the piston 8a of the pressure-intensifying cylinder 8 is waiting at the neutral position. On the other hand, the booster cylinder 8 and the oil tank 20
Are connected via a pipe 22.

Therefore, if the pipe 22 connecting the pressure-intensifying cylinder 8 and the oil tank 20 comes off due to vibration during running or is damaged due to inadvertent contact during maintenance work, etc. 8 has a problem that oil leaks out, especially when it occurs during running, causing oil to scatter around.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of the conventional boom device such as a fluid transport boom device and to provide a boom device which does not leak from an auxiliary cylinder when the boom is stored. I do.

[0011]

According to a first aspect of the present invention, there is provided a boom device, wherein a cylinder capable of raising and lowering a boom supported on a vehicle body is connected to the cylinder and a built-in piston waits at an intermediate position when the boom is not vibrating. An auxiliary cylinder capable of moving forward and backward to change the hydraulic pressure of the cylinder during boom vibration, a tank storing working fluid used for the auxiliary cylinder, and a liquid supply connecting the auxiliary cylinder and the tank via at least one valve. A boom device provided with a pipe, wherein, based on a withdrawal command signal input automatically or manually, a withdrawal control means for withdrawing the working fluid of the auxiliary cylinder to a tank via a liquid feed pipe is provided. I do.

A boom device according to a second aspect of the present invention is the boom device according to the first aspect, wherein the boom is supported on the vehicle body by a base joint portion so as to be able to undulate, and has an intermediate joint portion that can be bent at an intermediate portion with respect to the entire length. Wherein the cylinder is provided at a base joint portion and an intermediate joint portion, and is means for vertically driving a drive point of a boom, and the auxiliary cylinder is provided at at least one of the joint portions. It is characterized by.

According to a third aspect of the present invention, there is provided the boom device according to the first or second aspect, wherein the operating fluid stored in the tank is assisted via a liquid feed pipe based on a preparation command signal input automatically or manually. A preparatory control means is provided which causes the piston to wait at an intermediate position in the auxiliary cylinder by supplying the piston to the cylinder.

[0014]

FIG. 3 shows a concrete pump truck to which a boom device according to one embodiment of the present invention is applied. The body 32 is provided with a concrete pump (not shown) for feeding concrete. Also, the car body 3
2, a boom 34 is provided via a rotatable base 60 so as to be able to be raised and lowered. That is, the base 60 is mounted so as to be able to undulate in the vertical direction α around the drive point 62 of the base indirect portion 42 which is a connection portion between the base 60 and the boom 34, and to be able to pivot in the horizontal direction β. I have. The boom 34 is driven up and down because:
The cylinder 48.

The boom 34 includes a first boom 36, a second boom 38, and a third boom 40, and is rotatably connected by intermediate joints 44 and 46. A pipe 54 is provided along each of the booms 36, 38, and 40, and the root thereof is connected to a concrete pump, and the distal end thereof is a discharge port 56.

The cylinder 4 of each joint 42, 44, 46
By controlling the expansion and contraction of 8, 50, 52, boom 3
The discharge port 56 can be set at a desired position by changing the position of the discharge port 56. Thereafter, when the concrete pump is operated, the concrete can be discharged from the discharge port 56.

FIG. 1 shows a part of the configuration of the boom device.
The boom device includes the above-described cylinder 48, a booster cylinder 66 as an auxiliary cylinder, and an oil tank 7 that stores a working oil (working fluid) used for the booster cylinder 66.
6, driven by an engine 78, a pipe 82 which is a liquid supply pipe connecting between the pressure intensifying cylinder 66 and the oil tank 76, a servo valve 74 and an unload valve 84 which are valves provided in the pipe 82. A vibration suppression hydraulic pump 80 and a controller 70 are provided.

A pressure sensor 72 is provided in a pipe 90 connecting the first liquid chamber 48a of the cylinder 48 and the second liquid chamber 66c of the pressure increasing cylinder 66. A position sensor 68 for measuring the displacement of the piston 66a is attached to the pressure-intensifying cylinder 66. An accumulator 86 and a pressure sensor 88 are provided on the pipe 82 and between the unload valve 84 and the servo valve 74.

The controller 70, the servo valve 74, the unload valve 84, the position sensor 68, and the pressure sensor 88 constitute a sampling control means. Further, the controller 70, the servo valve 74, the unload valve 8
4. The preparation sensor is constituted by the position sensor 68 and the hydraulic pump 80 for damping. FIG. 2 is an enlarged circuit diagram near the servo valve 74 and the unload valve 84.

When the posture of the boom 34 (see FIG. 3) is changed, the solenoid valve 64 is controlled to change the pressure of the cylinder 48 provided on the first boom 36 so that the cylinder 48 can be changed.
Is changed. The angle of the first boom 36 is set to a desired angle by changing the stroke x. The same applies to the second boom 38 and the third boom 40. Thus, the boom 34 can be controlled to a desired posture. When the posture change of the boom 34 is completed, the solenoid valve 64 is closed.

In this embodiment, the cylinder 48 has a spring function for applying a force proportional to the displacement x and a damper function for applying a force proportional to the displacement speed.
A pressure increasing cylinder 66 is provided in addition to the cylinder 48. When no vibration is applied to the boom 34, the piston 66a of the pressure-intensifying cylinder 66 stands by at an intermediate position (neutral position) of the pressure-increasing cylinder 66. When vibration is applied to the boom 34, the stroke x of the cylinder 48 changes, and accordingly, the stroke of the pressure-intensifying cylinder 66 also changes.

The controller 70 determines the stroke x of the cylinder 48 based on the stroke of the pressure-intensifying cylinder 66 taken in through the position sensor 68, performs a predetermined calculation based on the stroke x, Calculate the pressure F. The controller 70 includes the pressure sensor 7
An output corresponding to the difference between the current pressure of the cylinder 48 and the target pressure F detected by 2 is supplied to the servo valve 74, and the pressure of the cylinder 48 is controlled so as to match the target pressure F.

That is, if the pressure of the cylinder 48 is higher than the target pressure F, the first liquid chamber 66 of the pressure-intensifying cylinder 66
b in an oil tank 7 provided in the vehicle body 32.
When the pressure of the cylinder 48 is smaller than the target pressure F, control is performed so that oil is supplied from the oil tank 76 to the first liquid chamber 66b of the pressure-intensifying cylinder 66.
The oil in the oil tank 76 is pressurized by a vibration damping hydraulic pump 80 driven by an engine 78,
Is supplied to the first liquid chamber 66b of the pressure-intensifying cylinder 66 via the

As described above, by controlling the pressure of the cylinder 48 via the pressure-intensifying cylinder 66,
By having a spring action and a damper action, the damping operation of the boom 34 can be performed during the concrete placing operation.

Next, referring to FIG. 4 while referring to FIG. 1, the first
The operation of extracting the working oil from the liquid chamber 66b will be described. When the placing operation is completed, the boom 34 is folded and stored in a predetermined position. At this time, the controller 70 monitors the input of the boom storage completion notice signal, which is the extraction command signal (step S2). The boom storage completion notice signal is issued from a boom storage sensor (not shown) that detects that the second boom 38 has been stored immediately before the storage of the boom 34 is completed.

When the boom storage completion notice signal is input, the controller 70 turns on the extraction operation lamp (not shown) (step S4) and opens the servo valve 74 to the oil tank 76 side (shown in FIG. Step S)
6). Immediately before the storage of the boom 34 is completed, the pressure in the first liquid chamber 48a of the cylinder 48, that is, the pressure in the second liquid chamber 66c of the pressure-intensifying cylinder 66 is larger than 0 (for example, about 50 to 60 kgf / cm ^2). ). Therefore, by opening the servo valve 74 to the oil tank 76 side, the operating oil in the first liquid chamber 66b of the pressure-intensifying cylinder 66 is pushed out to the piston 66a and discharged to the oil tank 76.

The controller 70 monitors whether or not the piston 66a has reached the bottom 66d based on a signal from the position sensor 68 (step S8).
When 6a reaches the bottom 66d, the servo valve 74 is closed (position (b) shown in FIG. 2), and the unload valve 8
4 is turned OFF (position (d) shown in FIG. 2) (step S10). By turning off the unload valve 84, the operating oil in the liquid chamber 86 a of the accumulator 86 is discharged to the oil tank 76.

The controller 70 monitors whether or not all the operating oil in the liquid chamber 86a of the accumulator 86 has been discharged based on a signal from the pressure sensor 88 (step S12). When the pressure is completely discharged and the supply pressure to the servo valve 74 becomes 0, the extraction operation lamp is turned off (step S14).

After confirming that the sampling operation lamp is turned off, the operator turns off a manual main switch (not shown),
End the sampling work. By turning off the manual main switch, all power supplies except the power supply for traveling the vehicle can be turned off.

Next, a preparation operation for causing the pressure-intensifying cylinder 66 to perform the above-described vibration suppression operation will be described with reference to FIG. Before starting the concrete placing operation, the operator first turns on the manual main switch (step S20). By turning on the manual main switch, the power supply related to
N.

When the manual main switch is turned on, the controller 70 monitors a signal input of either a boom raising start signal or a pump start signal, which is a preparation command signal (step S22). The boom raising start signal is issued when a boom raising switch (not shown) for raising the boom 34 is pressed. The pump start signal is
Occurs when a pump start switch (not shown) for starting a concrete pump for delivering concrete is pressed.

When any of the above signal inputs is received,
The controller 70 turns on the unload valve 84 (the position (e) shown in FIG. 2) and opens the servo valve 74 (the position (a) shown in FIG. 2) to thereby control the hydraulic pump 80 for damping. The operating oil pressurized by the accumulator 86 and the first liquid chamber 6
6b (steps S24, S26).

The controller 70 monitors whether or not the piston 66a has reached a predetermined neutral position (substantially the center of the pressure-intensifying cylinder 66 in this embodiment) based on a signal from the position sensor 68 (step S1). S28) When the piston 66a reaches the neutral position, the servo valve 7
4 is closed (position (b) shown in FIG. 2, step S3).
0), finish the preparation work. In this way, by performing the preparatory work, it becomes possible to perform the above-described vibration control operation in the concrete pouring work that is performed subsequently.

In the above embodiment, the boom storage completion notice signal is used as the extraction command signal in the extraction control means.
When the pressure in the first liquid chamber 48a of No. 8 is larger than 0,
A signal indicating boom storage completion may be used as the extraction command signal. In addition, a dedicated manual switch for starting the sampling operation may be provided, and a pressing signal of the switch may be used as a sampling command signal.

In the above-described embodiment, with respect to the preparation command signal in the preparation control means, it is assumed that the preparation command signal is input when at least one of the boom raising signal and the pump start signal is input. However, only the boom rise signal is
Alternatively, it may be configured to use only the pump start signal. It is also possible to set so that the preparation command signal is input when both the boom raising signal and the pump start signal are input. Further, the preparation command signal is not limited to the above signal. For example, a start signal or the like of the vibration damping hydraulic pump 80 can be used. Furthermore, a dedicated manual switch for starting the preparation operation may be provided, and a signal for pressing the switch may be used as a preparation command signal.

In the above-described embodiment, the cylinder is provided in the base indirect portion 42 and the intermediate indirect portions 44 and 46. However, the cylinder is provided in a portion other than the base indirect portion 42 and the intermediate indirect portions 44 and 46. It may be provided.

In the above-described embodiment, the pressure-intensifying cylinder 66 is provided in the cylinder 48 of the base indirect portion 42. However, the present invention is not limited to this. It can be configured to be provided in at least one of the indirect portion 42 and the intermediate indirect portions 44 and 46. Further, the pressure-intensifying cylinder 66 can be provided in a portion other than the indirect portion. Also, the oil tank 76,
The installation location of the servo valve 74 and the like is not particularly limited.

In the above embodiment, when the boom is not vibrating, the piston 66a is made to stand by almost at the center of the pressure-intensifying cylinder 66.
Is not necessarily required to be substantially at the center. Further, the booster cylinder 66 is used as the auxiliary cylinder, but other cylinders may be used.

In the above embodiment, two valves, the servo valve 74 and the unload valve 84, are provided between the auxiliary cylinder and the tank. However, one valve or three or more valves are provided. May be provided.

In the above embodiment, the boom device having the intermediate joint has been described. However, the present invention is also applicable to a boom device having no intermediate joint such as a telescopic boom and a boom device having a single boom. it can.

Further, in the above-described embodiment, the case where the present invention is applied to a concrete pump truck has been described as an example. However, the present invention is also applied to a vehicle having a boom device for delivering a fluid other than concrete. be able to.
Further, the present invention can be applied to a vehicle having a boom device such as an aerial work vehicle that does not involve the delivery of fluid.

[0042]

According to the first or second aspect of the present invention, the boom device is configured to automatically or manually input a sampling command signal.
It is characterized in that the operating fluid of the auxiliary cylinder is drawn out to a tank via a liquid sending pipe.

Therefore, when storing the boom, the operating fluid can be withdrawn from the auxiliary cylinder. Therefore, even when the liquid supply pipe is detached due to vibration during traveling or is damaged due to inadvertent contact during maintenance work, the operating fluid in the auxiliary cylinder does not leak. . That is, it is possible to realize a boom device that does not leak liquid from the auxiliary cylinder when the boom is stored.

According to a third aspect of the present invention, the boom device further supplies the operating fluid stored in the tank to the auxiliary cylinder through a liquid feed pipe based on a preparation command signal input automatically or manually. It is characterized in that the piston is made to stand by at an intermediate position in the cylinder.

Therefore, by supplying the operating fluid extracted from the auxiliary cylinder during storage of the boom to the auxiliary cylinder before using the boom, auxiliary driving by the auxiliary cylinder during use of the boom can be started quickly. be able to.

[Brief description of the drawings]

FIG. 1 is a drawing showing a part of a configuration of a boom device according to an embodiment of the present invention.

FIG. 2 is an enlarged circuit diagram in the vicinity of a servo valve and an unload valve in the configuration of the boom device according to one embodiment of the present invention.

FIG. 3 is a view showing an appearance when the boom device according to one embodiment of the present invention is applied to a concrete pump truck.

FIG. 4 is a flowchart for explaining a work of extracting hydraulic oil in the boom device according to the embodiment of the present invention.

FIG. 5 is a flowchart illustrating a preparation operation for a vibration control operation in the boom device according to the embodiment of the present invention.

FIG. 6 is a drawing showing a part of the configuration of a conventional boom device.

[Explanation of symbols]

 66 ····· Pressure increasing cylinder 66a ··· Piston 66b ··· First liquid chamber 66d ··· Bottom 68 ··· Position sensor 70 ··· Controller 74 ··· · Servo valve 76 · · · · Oil tank 84 · · · · · Unload valve 86 · · · · Accumulator 86a · · Liquid chamber 88 · · · Pressure sensor

Claims (3)

(57) [Claims] 1. A cylinder connected to a cylinder and capable of raising and lowering a boom supported on a vehicle body, wherein a built-in piston stands by at an intermediate position when the boom is not vibrating, and changes a hydraulic pressure of the cylinder when the boom vibrates. A boom device including an auxiliary cylinder that can be moved forward and backward, a tank that stores a working fluid used for the auxiliary cylinder, and a liquid feed pipe that connects the auxiliary cylinder and the tank via at least one valve. A boom device, comprising: a sampling control means for extracting the operating fluid of the auxiliary cylinder to a tank via a liquid feed pipe based on a sampling command signal input by the boom device. 2. The boom device according to claim 1, wherein the boom is supported on the vehicle body by a base joint so as to be able to undulate, and has an intermediate joint that can be bent at an intermediate portion with respect to the entire length. Boom device provided at a base joint portion and an intermediate joint portion, for driving a drive point of a boom in a vertical direction, wherein the auxiliary cylinder is provided at at least one of the joint portions. . 3. The boom device according to claim 1, wherein the operating fluid stored in the tank is supplied to the auxiliary cylinder via a liquid feed pipe based on a preparation command signal input automatically or manually. A boom device comprising: a preparatory control means for waiting the piston at an intermediate position in the auxiliary cylinder.