JPH1060953A - Protecting device for hydraulic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect the respective hydraulic equipment for forming a hydraulic circuit in a hydraulic actuator by quickly detecting the case where a pulsation absorbing accumulator is out of order in a hydraulic actuator in which pulsation is caused. SOLUTION: In a protecting device for hydraulic equipment, high pressure side and low pressure side oil pressure pipings 19, 20 of a braker 11 are provided with accumulators 28, the accumulator 28 of the oil pressure piping side is provided with a pressure switch 30H, and the accumulator 8 of the oil pressure side 20 is provided with a pressure switch 30L. The pressure switches 30H, 30L are respectively adapted to detect the pressure in the accumulators 28, 28, and operates a relay 31 when it exceeds a preset pressure to sound a buzzer 32 and to light an indicating lamp 33, thereby informing an operator of an failure of an accumulator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic device mounted on a hydraulic machine such as a hydraulic shovel, for example, when a hydraulic actuator generating a pulsation is operated, the pulsation damages each hydraulic device constituting a hydraulic circuit. Related to a hydraulic device protection device for preventing
In particular, the present invention relates to a hydraulic device protection device that ensures the safety of each hydraulic device constituting a circuit configuration even when an accumulator provided for absorbing pulsation is damaged.

[0002]

2. Description of the Related Art An example of a hydraulic machine is a hydraulic shovel, for example. As shown in FIG. 9, the hydraulic excavator generally has an upper revolving unit 2 rotatably mounted on a lower traveling unit 1. The driver cab 3 is installed on the upper revolving unit 2, and a front working mechanism 4 is provided. Is provided. The front working mechanism 4 includes a boom 5 provided on the frame of the upper swing body 2 so as to be capable of raising and lowering, an arm 6 connected to the tip of the boom 5 so as to be vertically rotatable, and a link mechanism 7 at the tip of the arm 6. And a front attachment connected so as to be able to perform joint movement. The boom 5 is provided by a boom cylinder 8 and the arm 6 is provided by an arm cylinder 9
Driven by The front attachment is driven by a link driving cylinder 10 generally called a bucket cylinder. here,
In a hydraulic shovel, a bucket is usually attached as a front attachment, but various attachments other than the bucket can be attached. Therefore, as an example of this attachment, FIG. 9 shows a state in which a hydraulically driven breaker 11 is mounted.

[0003] As shown in FIG.
In the breaker 11, a cylinder 13 is formed in the breaker body 12, a piston 14 is slidably mounted in the cylinder 13, and a chisel 15 is provided so as to protrude from the breaker body 12, and the piston 14 reciprocates. Thus, the chisel 15 is configured to be hit. In order to reciprocate the piston 14, a supply port 16 and a discharge port 17 and a reciprocation switching means 18 are provided in the breaker main body 12.
6, a plurality of oil passages are connected between the discharge port 17, and the supply port 16 and the discharge port 17 are respectively provided with hydraulic piping 19,
20 are connected. Therefore, the piston 14 slides in the cylinder 13 by the pressure oil supplied from the supply port 16, and during this reciprocating stroke, the reciprocating switching means 18 causes the piston rear chamber, the piston front chamber, and the supply port to move. The connection state between the discharge port 16 and the discharge port 17 is switched. The breaker 11 is used for repeatedly breaking and breaking concrete, rocks, and other lumps by the breaker body 12.
The impact is applied at a high speed, for example, several tens of times or more per minute.

[0006] FIG. 11 shows a hydraulic circuit for driving the breaker 11. In the figure, reference numeral 21 denotes a main pump, and reference numeral 22 denotes a pilot pump. Pressure oil supplied from the main pump 21 is supplied to a hydraulic pipe 19 on the high pressure side of the breaker 11 via a direction switching valve 23. The directional control valve 23 is normally held at a position where the communication between the main pump 21 and the breaker 11 is cut off. In order to control the switching of the directional control valve 23,
An operation means 24 including a pilot valve 24b operated by an operation pedal 24a or the like is provided. When the operating means 24 is operated, the pilot pressure from the pilot pump 22 is supplied to the hydraulic pilot portion 23a of the direction switching valve 23, and the direction switching valve 23 connects the main pump 21 and the breaker 11 from the neutral position. The pressure oil is supplied to the hydraulic pipe 19 connected to the supply port 16 of the breaker 11. Also, the discharge port 1 of the breaker 11
7 is connected to the filter 2 on the low pressure side.
5 and a check valve 26 to be connected to a hydraulic oil tank 27.

Since the flow path of the breaker 11 is switched at a high speed by the reciprocating movement switching means 18, pulsation occurs when the flow path is switched. In particular, the peak pressure of the pulsation on the high pressure side, that is, the hydraulic pipe 19 side becomes extremely high, and this pulsation adversely affects hydraulic equipment such as the directional switching valve 23 and the main pump 21 connected to the hydraulic pipe 19, and is extremely severe. May cause these hydraulic devices to fail. In addition, pulsation also occurs on the low pressure side, that is, on the hydraulic pipe 20 side, though not as high as the high pressure side. Since the filter 25 is provided on the hydraulic piping 20 side, the filter 25 may be damaged by pulsation.

From the above, the accumulator 28 (in the following description, in order to distinguish between the high-pressure side and the low-pressure side, the high-pressure side accumulator 28H , The accumulator on the low pressure side is denoted by 28L). As shown in FIG. 12, the accumulator 28 is provided in the middle of the pipe C, and has a configuration in which a bladder 28b made of a flexible film that partitions the interior of the pressure-resistant container 28a into two chambers is provided. Pressure-resistant container 2 partitioned by bladder 28b
One of the two chambers 8a is a gas chamber G filled with a gas of a predetermined pressure, and the other chamber is a pipe C
The working chamber W is opened to the outside. As a result, when the pressure in the pipe C changes, the pressure in the working chamber W communicating with the pipe C also becomes high, so that the gas chamber G is compressed, and the pulsation is absorbed by the expansion and contraction of the gas chamber G. be able to.

[0007]

Incidentally, in the accumulator 28, the bladder 28b for defining the gas chamber G and the working chamber W is formed of a flexible film. There is. Even if the bladder 28b is damaged to the extent that pinholes are generated, the gas in the gas chamber G flows out and the pulsation absorbing function is not exhibited. Moreover,
Even if the bladder 28b is damaged, the occurrence of such an accident often cannot be recognized by the operator, and therefore, the operation of the breaker 11 may be continued in a state where pulsation occurs. Then, eventually, each hydraulic device constituting the hydraulic circuit may be damaged.

In consideration of the above points, two accumulators 28 are connected to the hydraulic piping 1 as shown in FIG.
There is also known one configured to be provided at 9,20.
With such a configuration, even if one accumulator is damaged, the other one accumulator is still operable, so that the pulsation absorbing function is maintained. However, two accumulators 2 are provided in each hydraulic pipe 19, 20.
The arrangement of the hydraulic circuit 8 not only complicates the configuration of the hydraulic circuit but also makes it impossible to detect a failure of the accumulator. Therefore, the operation may continue with one accumulator damaged, and in this state, the other accumulator may be operated. If it is damaged, the pulsation absorbing function is lost, so that it is not necessarily perfect from the viewpoint of safety protection of hydraulic equipment.

The present invention has been made in view of the above points, and an object of the present invention is to quickly detect a failure of a pulsation absorbing accumulator in a hydraulic actuator in which pulsation occurs. By
An object of the present invention is to protect each hydraulic device constituting a hydraulic circuit in the hydraulic actuator.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an accumulator provided at least in the middle of a high pressure side pipe to a hydraulic actuator in which pulsation occurs. Or a pressure detecting means provided in a pipe connected to the accumulator, and an alarm means for generating at least an alarm when the pressure detecting means detects a pressure equal to or higher than a predetermined value. It is.

[0011] Among the pipes to the hydraulic actuator, the pipe on the high pressure side generates larger pulsation, so that at least the pipe on the high pressure side is provided with an accumulator and a pressure detecting means. Further, since hydraulic equipment such as a filter is also provided in the low-pressure pipe, it is preferable to provide the accumulator and the pressure detecting means also in the low-pressure pipe. Here, the pressure detecting means can be provided in a pipe or an accumulator, and from the viewpoint of simplification of the configuration, it is preferable to use a pressure switch that turns ON and OFF at a predetermined set pressure. preferable. Further, since there is a difference in the pressure flowing through the pipe between the high-pressure side and the low-pressure side, the peak pressure generated when the accumulator is damaged is different.
Therefore, by changing the set pressure of each pressure switch on the high pressure side and the low pressure side, damage to the accumulator can be detected more accurately.

Even when the accumulator is operating normally, pressure fluctuations may occur due to the load on the hydraulic actuator and the like. The pressure in this case shows irregular fluctuations. On the other hand, when the accumulator is damaged, the pressure fluctuation has some regularity. Therefore,
If the pressure fluctuation is simply detected by the above-described pressure detecting means, there is a possibility that an erroneous detection may be made even though the accumulator has not actually failed. Therefore, for example, by measuring the time exceeding the set pressure or detecting the number of peak values equal to or higher than the set value, it is possible to discriminate between the pressure change caused by the failure of the accumulator and the pressure change caused by other reasons. Becomes possible.

The alarm means is a means for allowing the operator to recognize that the accumulator has been damaged, and is constituted by, for example, a display lamp or an alarm buzzer, and these can be used alone or in combination. In addition, from the viewpoint of protection of the hydraulic equipment, the flow rate supplied to the hydraulic actuator is not only alarmed, but also to stop the operation of the hydraulic actuator or to suppress the pulsation to such an extent that the hydraulic equipment is not damaged. It is also possible to provide a pressure oil supply restricting means for reducing the pressure oil supply. However, as it is, the whole machine will not work. Therefore, in order to prevent such a situation, a configuration may be adopted in which, when the operation of the hydraulic actuator that causes pulsation is stopped, the restriction state by the pressure oil supply restriction unit is released. Further, the directional control valve connected to the hydraulic actuator may be forcibly returned to the neutral position.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described. First, FIGS. 1 to 3 show a first embodiment of the present invention.
The same reference numerals are given to the same or equivalent members as in the above-described related art, and the description thereof is omitted. In the following, a breaker will be described as a hydraulic actuator in which pulsation occurs. However, in addition to this breaker, a hydraulic device protection device having a similar configuration can be applied to a hydraulic actuator in which pulsation may occur. Needless to say.

In FIG. 1, reference numerals 30H and 30L denote pressure switches as pressure detecting means (when the pressure switches are collectively referred to, reference numeral 30 is used). As shown in FIG. The pressure in the pressure-resistant container 28a of the accumulator 28 is detected.
Here, the pressure switch 30 is provided on both accumulators 28 provided on the high pressure side and the low pressure side hydraulic pipes 19 and 20. The set pressure of the pressure switch 30H of the accumulator 28H on the hydraulic pipe 19 side is set on the hydraulic pipe 20 side. Is higher than the set pressure of the pressure switch 30L of the accumulator 28L.

The pressure in accumulators 28H and 28L is detected by pressure switches 30H and 30L, respectively.
When the set pressure is exceeded, the relay 31 is activated, the buzzer 32 provided in the cab 3 sounds, and the display lamp 3
3 lights up. The buzzer 32 and the display lamp 33 serve as alarm means to notify the operator that the accumulator 28 has been damaged.

As shown in FIG. 3, the accumulator 28
During normal operation of the (T _N), by the action of the accumulator 28, the peak pressure of the pulsation of the pressure oil flowing through the hydraulic pipes is lowered so that P _1. On the other hand, when the accumulator 28 fails (T _U ), if the expansion and contraction of the gas chamber G is not performed, the peak pressure of the pulsation becomes P
_It will be as high as ₂ . Therefore, the set pressure of the pressure switch 30 is set to SP. As a result, when the accumulator 28 is operating normally, when the breaker 11 as a hydraulic actuator causing pulsation is operated, pulsation occurs due to the repetitive switching of the reciprocating drive switching means 18 in the breaker 11. also, the absorption of the pulsation accumulator 28 is performed, the peak pressure is suppressed in a range of P _1. Therefore, the pressure switch 30 does not turn on.

However, when the pulsation absorbing function is impaired due to the failure of the accumulator 28, that is, the damage of the bladder 28b, the peak pressure of the pulsation becomes P _2.
And higher. Since the set pressure of the pressure switch 30 is set between the P ₁ and P _2, when the peak pressure P ₂ is generated, the pressure switch 30 will be turned ON. As a result, the relay 31 is activated, the buzzer 32 sounds, and the display lamp 33 is turned on, so that the operator who operates the excavator can recognize the failure of the accumulator 28 both audibly and visually. Therefore, when the accumulator 28 fails, the breaker 1
By stopping the work by the operation of the first operation, each hydraulic device provided in the hydraulic circuit for operating the breaker 11, for example, the main pump 21, the direction switching valve 23 (high-pressure side hydraulic device), the filter 26, and the check valve 27 (Low-pressure-side hydraulic equipment) and the like are protected.

As described above, when the accumulator 28 fails, the operator can immediately recognize the failure, so that the occurrence of the failure of the accumulator 28 which cannot be recognized in a normal state can be immediately recognized, and the operator can recognize the hydraulic equipment. Appropriate and prompt measures can be taken to protect

In addition to the buzzer 32 and the indicator lamp 33, as shown in FIG. 4, the electromagnetic switching valve 3 is provided in the middle of the pipe between the operating means 24 and the hydraulic pilot portion of the direction switching valve 23.
4 can also be provided. Then, the accumulators 28H or 28L are operated by the pressure switches 30H and 30L.
Is detected, the buzzer 32 sounds,
The display lamp 33 is turned on, and the electromagnetic switching valve 34 is switched. As a result, the direction switching valve 23 returns to the neutral position, and the breaker 11 is not supplied with pressure oil.

Accordingly, even if the operator operates the operating means 24 to ignore the warning by the warning means and continues the operation of the breaker 11, even if the operating means 24 is operated, the direction switching valve 23 is not operated.
Is locked in the neutral position, so that no pressure oil is supplied to the breaker 11. Therefore, when the accumulator 28 breaks down, it is possible to more reliably prevent the hydraulic equipment from being damaged due to pulsation.

By the way, even if the accumulator 28 is not out of order, the possibility that the pressure in the hydraulic circuits 19 and 20 exceeds the set value SP for some reason cannot be denied. In this case, if an alarm is given by the alarm means or if the operation of the breaker 11 is stopped, the work will be hindered. Therefore, it is preferable that only when the accumulator 28 breaks down is detected and an alarm is issued by the alarm means, or the breaker 11 is stopped as necessary.

As shown in FIG. 5 (a), when the accumulator 28 is not provided or when the accumulator 28 is damaged, the pressure fluctuation caused by the pulsation generated when the breaker 11 is operated is low. There are a frequency component and a high frequency component, and in the low frequency component, the low pressure state and the high pressure state are almost regularly repeated. On the other hand, as shown in FIG.
Even when the accumulator 28 is operating, momentarily high peak pressures can occur. That is, when the accumulator 28 is not operated, the extremely high pressure state exceeding the set pressure value SP continues for at least the time Δt. On the other hand, as long as the accumulator 28 is operating, even if the peak pressure exceeds the set pressure value SP, it is instantaneous and immediately drops below the set pressure value SP. The pressure switch 30 is turned on when a pressure state higher than the set pressure SP is detected, and as long as the pressure equal to or higher than the set pressure SP continues.

From the above, as shown in FIG. 6, a microcomputer 35 is provided to turn on and off the relay 31.
The high-voltage state is maintained for a predetermined time Δt after receiving the OFF signal, that is, the relay 31 is turned ON for the time Δt.
When the state is continued, it is determined that the accumulator 28 is damaged, and the buzzer 32 which is the alarm means and the display lamp 33 are turned on. As a result, it is possible to prevent erroneous detection of a pressure fluctuation caused by a cause other than the pulsation occurring in the hydraulic pipings 19 and 20 as damage to the accumulator 28.

By the way, pulsation at the time of failure of the accumulator 28 occurs only when the breaker 11 is operating. Whether or not the breaker 11 is operating can be detected from the operating means 24 based on whether or not the pressure oil of the pilot pump 22 is supplied to the hydraulic pilot portion of the direction switching valve 23. Therefore, the pipe 36 between the operating means 24 and the hydraulic pilot portion of the direction switching valve 23
Pressure switch 37 is provided. Thus, when the breaker 11 is not operated, for example, the breaker 11
While operating the boom 5 and the arm 6, etc. to aim at the lump to break the chisel 15 of
Even if the chisel 15 collides with the lump and the pressure in the hydraulic pipes 19 and 20 changes due to the impact, it is possible to prevent the pressure from being determined as a failure of the accumulator 28.

Since the microcomputer 35 detects whether or not the breaker 11 is operating with the second pressure switch 37, the buzzer 32 which constitutes alarm means only when the breaker 11 is operating. And the display lamp 33 is turned on.

When the operating means 24 is operated in spite of the alarm means being operated, the breaker 11
It is necessary to prevent the operation of the pump regulator 38.
May be configured to be controlled. That is, the discharge flow rate of the main pump 21 is controlled by the pump regulator 38. When the pump regulator 38 is set to the minimum discharge flow state, even if the directional control valve 23 is switched, it is necessary to operate the breaker 11. Unable to supply pressure oil at the flow rate. Therefore, an electromagnetic switching valve 40 is provided in a pipe 39 leading from the pump regulator 38 to the hydraulic oil tank 27, and the electromagnetic switching valve 40 is normally kept closed in the flow path, and based on a signal from the microcomputer 35, The electromagnetic switching valve 40 is opened so that the pump regulator 38 communicates with the hydraulic oil tank 27.

With the above arrangement, even after the accumulator 28 is detected to be out of order, the main pump 21 is kept at the minimum discharge flow rate even if the operating means 24 is operated. The breaker 11 is kept stopped, and no large pulsation occurs. Moreover,
When the operation of the operation means 24 is stopped, the electromagnetic switching valve 40
As a result, the communication between the pump regulator 38 and the hydraulic oil tank 27 is interrupted, so that there is no hindrance to operating other hydraulic actuators.

When the breaker 11 is operated, the main pump 21 is normally operated at the maximum discharge flow rate.
In addition, the engine is set to the maximum rotation state, and the high-pressure oil is supplied to the breaker 11, so that the lump is efficiently destroyed. Under such conditions, the accumulator 28
Is inoperable, an extremely high-impact pulsation that causes damage to the hydraulic equipment occurs. However, if the pressure oil supplied to the breaker 11 is in a lower pressure state, even if the accumulator 28 is inoperable, an accident such as breakage of the hydraulic equipment does not occur. Of course, if this is done, the efficiency of work such as destruction of lump will decrease, but even in such a low pressure state,
Work is never impossible.

As described above, when the accumulator 28 becomes inoperable during the operation of the breaker 11, the operation of the breaker 11 is continued in a pressure state which does not adversely affect each hydraulic device constituting the hydraulic circuit. It is preferred that For this purpose, based on a signal from the microcomputer 35, the discharge flow rate of the main pump 21 by the pump regulator 38 is limited as shown in FIG.
(And the pilot pump 22)
When the governor 42 is controlled by the motor 43, the rotation speed of the engine 41 can be controlled based on a signal from the microcomputer 35. In this way, even if the accumulator 28 is inoperable, the microcomputer 35 stores in advance the control data on the pump discharge flow rate or the engine speed that does not cause the hydraulic device to be damaged, so that the Can perform the destruction work of the lump.

[0031]

As described above, according to the present invention, when an accumulator provided in a pipe from a hydraulic actuator in which pulsation occurs fails, the accumulator is detected by a pressure detecting means, and the operator is recognized by an alarm means. With this configuration, when the accumulator fails, it is possible to quickly detect the failure, thereby providing an effect such as protection of each hydraulic device constituting a hydraulic circuit in this hydraulic actuator.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram for driving a hydraulic actuator including a hydraulic device protection device according to an embodiment of the present invention.

FIG. 2 is a sectional view of an accumulator incorporating a pressure switch.

FIG. 3 shows a state in which the accumulator is operating normally;
It is a pressure waveform diagram which shows the pressure fluctuation | variation of the pressure oil which flows through a hydraulic piping in the inoperable state of an accumulator.

FIG. 4 is a hydraulic circuit diagram for driving a hydraulic actuator including a hydraulic device protection device according to another embodiment of the present invention.

FIG. 5 is a hydraulic circuit diagram for driving a hydraulic actuator including a hydraulic device protection device according to another embodiment of the present invention.

FIG. 6 is a pressure waveform diagram showing a comparison between pulsation due to inability to operate the accumulator and pressure fluctuations of other pressure oil.

FIG. 7 is a hydraulic circuit diagram for driving a hydraulic actuator including a hydraulic device protection device according to still another embodiment of the present invention.

FIG. 8 is a hydraulic circuit diagram for driving a hydraulic actuator including a hydraulic device protection device according to still another embodiment of the present invention.

FIG. 9 is an external view of a hydraulic shovel as an example of a hydraulic machine.

FIG. 10 is a configuration explanatory view of a breaker as a hydraulic actuator in which pulsation occurs.

FIG. 11 is a hydraulic circuit diagram for driving a breaker according to the related art.

FIG. 12 is a hydraulic circuit diagram for driving a breaker having a hydraulic device protection mechanism according to the related art.

FIG. 13 is a circuit diagram showing a main part of a hydraulic circuit for driving a breaker according to another conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Breaker 19, 20 Hydraulic piping 21 Main pump 22 Pilot pump 23 Direction switching valve 24 Operation means 25 Filter 26 Check valve 27 Hydraulic oil tank 28, 28H, 28L Accumulator 30, 30H, 30L Pressure switch 31 Relay 32 Buzzer 33 Indicator lamp 34 , 40 Solenoid switching valve 35 Microcomputer 37 Second pressure switch 38 Pump regulator 41 Engine

Claims (9)

[Claims] 1. A hydraulic circuit comprising: a hydraulic pump; a hydraulic actuator driven by pressure oil supplied from the hydraulic pump; and a direction switching valve for switching between the hydraulic pump and the hydraulic actuator. Among the hydraulic actuators, an accumulator provided at least in the middle of the high pressure side pipe to the hydraulic actuator where pulsation occurs, pressure detection means for detecting the pressure in the high pressure side pipe, and a predetermined value or more by the pressure detection means And a warning means for generating at least a warning when the pressure is detected. 2. An accumulator and a pressure detecting means are provided in a high pressure side and a low pressure side pipe connected to the hydraulic actuator in which the pulsation occurs, and when both of these pressure detecting means detect a pressure equal to or more than a predetermined value, 2. The hydraulic equipment protection device according to claim 1, wherein an alarm is generated by an alarm unit. 3. The hydraulic equipment protection device according to claim 2, wherein said pressure detecting means comprises a pressure switch, and is configured to change a set pressure of a pressure switch between a high pressure side and a low pressure side. 4. The hydraulic pressure according to claim 1, wherein said pressure detecting means includes an identification means for distinguishing between a pressure fluctuation caused by breakage of said accumulator and other pressure fluctuations. Equipment protection device. 5. The hydraulic device according to claim 1, further comprising a pressure oil supply restricting unit that stops or restricts the supply of the pressure oil to the hydraulic actuator in which the pulsation occurs, together with the alarm unit. Protective equipment. 6. The hydraulic equipment protection device according to claim 5, wherein the pressure oil supply restricting means restricts the number of revolutions of the engine. 7. The hydraulic pump according to claim 5, wherein said hydraulic pump is a variable displacement hydraulic pump, and said pressure oil supply restricting means restricts a discharge flow rate of said hydraulic pump.
The described hydraulic equipment protection device. 8. The hydraulic device protection device according to claim 5, wherein when the operation of the hydraulic actuator is stopped, the restriction by the pressure oil supply restricting means is released. 9. The hydraulic equipment protection device according to claim 5, wherein said pressure oil supply restricting means comprises a switching means for switching a direction switching valve connected to a hydraulic actuator in which said pulsation occurs to a neutral position. .