JPH09250510A - Protecting device for hydraulic circuit in working machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively protect various hydraulic devices, provided on a hydraulic circuit, by making constitution, wherein a pressure loss detecting means, for detecting the pressure loss of hydraulic fluid by a filter, and an output lowering means, for lowering the output of an hydraulic circuit, are provided to actuate the output lowering means based on a detected pressure loss value is exceeding a preset value. SOLUTION: In a control part 35, in the cases where a filter is in a blinding condition, and timing for maintenance is judged, or the contamination of hydraulic fluid is progressed, and timing for replacement is judged; corresponding anounciators 37, 38, and 39 inform these judgements to an operator, to urge maintenance, and also an engine rotation frequency is reduced to a low rotation frequency, thereby lowering the output of a hydraulic circuit. Consequently, oil pressure output, applied to the various kind hydraulic devices such as a hydraulic actuator, or a piping and a valve etc., provided on the hydraulic circuit, can be reduced, thereby effectively protecting these hydraulic devices.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a hydraulic circuit provided in a hydraulic working machine such as a hydraulic excavator.

[0002]

2. Description of the Related Art Generally, hydraulic oil in a hydraulic circuit provided in this type of hydraulic working machine is produced by molding sand, polishing powder, dust entering from the outside during manufacturing of a hydraulic system, or dust generated during operation of the hydraulic system. It is polluted by various contaminants such as metal powder and oil deterioration, which adversely affect the performance and life of the hydraulic system. Filter is disposed in the hydraulic circuit. By the way, since the filter gradually becomes clogged with contaminants as it is used, it is necessary to properly inspect and clean it or replace the filter medium. Since the filter is clogged differently depending on factors such as the situation, it is difficult to know the exact time of inspection because the filter is already severely clogged at the time of inspection, or conversely it is almost not clogged. It was Therefore, the hydraulic circuit is provided with pressure detection means for detecting pressure loss due to the filter, and when the pressure loss value detected by the pressure detection means exceeds a preset value, it is determined that the filter is in a clogged state. Then, it is proposed to notify the operator of this, and to prompt maintenance such as cleaning and replacement of the filter.

[0003]

However, in this case, since only the clogging of the filter is notified,
The operator does not immediately stop the work and perform maintenance such as cleaning of the filter when the above notification is given, and continues the work to a good cut place before performing the maintenance or a specialized service. The work may continue until the man arrives. By the way, if the work is continued while the filter is still clogged in this way, the filter will be damaged by high pressure, or if the filter has a relief valve, it will be filtered by the filter. Instead, the hydraulic oil will flow through the relief valve, and the hydraulic operation will be carried out without removing contaminants, which adversely affects the performance and life of the hydraulic system. There was a problem to be solved by the invention. Further, when the contamination of the hydraulic oil progresses, it is necessary to replace the hydraulic oil. However, it has been proposed to detect the degree of contamination of the hydraulic oil and notify the operator of this even at the time of replacing the hydraulic oil. However, since this is also just a notification,
There was the same problem to be solved as in the case of the aforementioned filter clogging.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the circumstances as described above with the object of solving these problems, and a hydraulic actuator that operates based on the supply of hydraulic oil is provided. A work machine including a hydraulic circuit provided with the filter, a filter for removing contaminants in the hydraulic oil, a pressure loss detection means for detecting a pressure loss of the hydraulic oil by the filter, and a reduction in the output of the hydraulic circuit. For reducing the pressure loss value, the output loss reducing means is activated when the pressure loss value detected by the pressure loss detecting means exceeds a preset value. By doing so, when the filter is clogged and the pressure loss value becomes equal to or greater than the preset value, the output reduction means operates to reduce the output of the hydraulic circuit. The hydraulic pressure acting on various hydraulic devices such as hydraulic actuators, pipes and valves provided in the hydraulic circuit is reduced, and these hydraulic devices can be effectively protected.
Further, according to the present invention, in a working machine including a hydraulic circuit provided with a hydraulic actuator that operates based on the supply of hydraulic oil, pollution degree detection means for detecting the degree of pollution in hydraulic oil and output of the hydraulic circuit are reduced. The output reducing means is provided for operating the output reducing means when the contamination degree detected by the contamination degree detecting means is equal to or more than a preset value. By doing so, when the degree of contamination of the hydraulic oil exceeds a preset value, the output lowering means operates and the output of the hydraulic circuit lowers. Similarly,
You can protect the hydraulic system. Among these, as the output lowering means, one that lowers the output of the hydraulic circuit by lowering the rotation speed of the engine that drives the hydraulic pump that is the hydraulic source of the hydraulic circuit, the output of the hydraulic pump that is the hydraulic source of the hydraulic circuit One that lowers the output of the hydraulic circuit by lowering the horsepower, one that lowers the output of the hydraulic circuit by lowering the maximum flow rate of the hydraulic pump that is the hydraulic source of the hydraulic circuit,
A device that reduces the maximum pressure of the main oil passage by lowering the set pressure of the main relief valve installed in the main oil passage that extends from the hydraulic pump that is the hydraulic pressure source of the hydraulic circuit to the oil tank, and the pilot oil passage provided in the hydraulic circuit The pilot circuit relief valve installed in the hydraulic pressure circuit is set to lower the maximum pressure in the pilot oil passage to reduce the spool movement amount of the control valve installed in the hydraulic circuit to control the pressure supply of the hydraulic actuator. It is possible to employ an appropriate output reducing means such as one that reduces the output of the control valve. Further, in this construction, the work machine is provided with an informing means for informing the operator based on the detection that the output lowering means operates, whereby the operator can be prompted to perform maintenance on the filter or the hydraulic oil.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 is a hydraulic excavator, and the hydraulic excavator 1 includes a crawler type lower traveling body 2, an upper swinging body 3 swingably supported above the lower traveling body 2, and an upper swinging body 3. The front attachment 4 is attached to the front part, and the like. Further, the left and right traveling motors 5 and 6, a swing motor 7 that swings the upper swing body 4, a boom 8 and an arm 9 that configure the front attachment 4 are provided. , A boom cylinder 11 for swinging the bucket 10, an arm cylinder 12,
The basic configuration, such as the provision of various hydraulic actuators such as the bucket cylinder 13 and the like, is conventional.

The pressure oil supply to each hydraulic actuator will be described with reference to the hydraulic circuit diagram shown in FIG.
In FIG. 2, 14 is a main pump driven based on the power of the engine E, 15 is a pilot pump, 16 is an oil tank, 17, 18, 19, 20, 21, and 22 are left and right traveling motors 5 and 6, respectively, and a turn. Motor 7, arm cylinder 12, boom cylinder 11, bucket cylinder 13
Control valves for each of the control valves 17 to 2
2 is each pilot valve 23, 24, 2 which is switched according to the operation of the corresponding operation lever (not shown).
Based on the supply of pilot pressure oil from 5, 26, 27 and 28, the neutral position where pressure oil is not supplied to the corresponding hydraulic actuator is switched to the pressure oil supply position where pressure oil is supplied.

Further, 29 and 30 are first and second filters, and the first filter 29 includes the control valves 17-
It is arranged in the main tank oil passage A from the tank port T of 22 to the oil tank 16, and the second filter 30
Is from the pilot pump 15 to each pilot valve 23.
~ 28 pilot pump oil passage B to pump port P
It is located in. These first and second filters 29, 30
Is provided with relief valves 29a and 30a that open when the pressure on the upstream side of the first and second filters 29 and 30 becomes equal to or higher than the set pressures P1 and P2.
It is possible to prevent the second filters 29 and 30 from being damaged due to high pressure.

Further, 31 is a main relief valve, and the main relief valve 31 is branched from a main pump oil passage C extending from the main pump 14 to the pump ports P of the control valves 17 to 22 and is connected to the main tank oil. Although arranged in the main relief oil passage D that joins the passage A, the main relief valve 31 is configured to open when the pressure in the main pump oil passage C becomes equal to or higher than the set pressure P3. Thus, the maximum pressure of the main pump oil passage C is set to be maintained at the set pressure P3.

Reference numeral 32 is a relief valve of the pilot circuit, and the pilot circuit relief valve 32 branches from the pilot pump oil passage B to the oil tank 16 from the tank port T of each pilot valve 23-28. It is arranged in the pilot relief oil passage F which joins the pilot tank oil passage E, but the pilot circuit relief valve 32 is opened when the pressure in the pilot pump oil passage B becomes equal to or higher than the set pressure P4. Is composed of
As a result, the maximum pressure of the pilot pump oil passage B is set to be maintained at the set pressure P4.

On the other hand, 33 and 34 are pressure detection sensors for detecting the pressure loss due to the first and second filters 29 and 30, and the detection values of these pressure detection sensors 33 and 34 are the control units described later. It is configured to be output to 35.

Further, reference numeral 36 denotes a pollution degree detecting sensor for detecting the degree of contamination of the hydraulic oil, which is provided in the oil tank 16 and has a metal amount and a fine particle amount in the hydraulic oil. It is configured to detect the degree of contamination of the hydraulic oil, such as the degree of oxidation and the degree of alkalinity, and output the detected value to the control unit 35.

The control unit 35 is composed of a microcomputer, etc., and inputs signals from the pressure detection sensors 34, 35 and the contamination degree detection sensor 36 as described above, and based on the input signals. A control command is output to first and second filter alarms 37 and 38, a hydraulic oil alarm 39, and a governor actuator 40 for switching the rotation speed of the engine E, which will be described later.

That is, the control unit 35, when the pressure loss value input from each pressure detection sensor 33, 34 is equal to or more than a preset value, the corresponding first and second filters 2
It is judged that it is time to perform maintenance because 9 and 30 are in a clogged state, and a control command for issuing a notification is output to the first and second filter alarm devices 37 and 38, and
A control command is output to the governor actuator 40 to reduce the engine speed to a preset low speed.

Further, the control unit 35 includes a pollution degree detecting sensor 3
When the detected value input from 6 is equal to or greater than a preset value, it is determined that the hydraulic oil is contaminated and it is time to replace the hydraulic oil, and the hydraulic oil alarm 39 is instructed to issue a control command for issuing an alarm. And a control command to the governor actuator 40 to reduce the engine speed to a preset low speed. here,
The first and second filter annunciators 37, 38 and the hydraulic oil annunciator 39 are composed of appropriate informing means such as a monitor display, a lamp, a buzzer, etc. Has been done.

When the control unit 35 determines that it is time to perform maintenance because the first and second filters 29 and 30 are in a clogged state as described above in the configuration as described above. If it is determined that the hydraulic oil is contaminated and it is time to replace it, the corresponding alarms 37, 38, 39 notify the operator to prompt maintenance, and the engine speed is low. The rotation speed is reduced to a lower value, which reduces the output of the hydraulic circuit.

As a result, the first and second filters 29, 30
If the oil is clogged or the hydraulic oil is contaminated, the output of the hydraulic circuit will automatically decrease and various hydraulic pressures such as hydraulic actuators, pipes, valves, etc. installed in the hydraulic circuit will be reduced. The hydraulic output acting on the devices is reduced, and these hydraulic devices can be effectively protected. Moreover, since the working capacity of the hydraulic excavator 1 also decreases with the decrease in the hydraulic output, the operator can feel the necessity of maintenance and prompt action can be taken.

Of course, the present invention is not limited to the above-mentioned embodiment, and the means for reducing the output of the hydraulic circuit is to reduce the output horsepower of the main pump 14 so that the maximum flow rate of the main pump 14 is reduced. The pilot circuit relief valve 32 lowers the set pressure P3 of the main relief valve 31 to lower the maximum pressure of the main pump oil passage C.
Is set to reduce the maximum pressure of the pilot pump oil passage B, thereby reducing the spool movement amount of the control valves 17 to 22 and reducing the output of the control valves 17 to 22. It can be adopted, and even when such an output reducing means is used, the same operation and effect as those of the above-mentioned embodiment can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of a hydraulic excavator.

FIG. 2 is a hydraulic circuit diagram of a hydraulic excavator.

FIG. 3 is a block diagram showing input / output to / from a control unit.

[Explanation of symbols]

 14 main pump 17 control valve 18 control valve 19 control valve 20 control valve 21 control valve 22 control valve 29 first filter 30 second filter 31 main relief valve 32 pilot circuit relief valve 33 first filter pressure detection sensor 34 second filter pressure Detection sensor 36 Pollution degree detection sensor 37 First filter alarm 38 Second filter alarm 39 Hydraulic oil alarm 40 Governor actuator

Claims (8)

[Claims] 1. A working machine comprising a hydraulic circuit provided with a hydraulic actuator that operates based on the supply of hydraulic oil, a filter for removing contaminants in the hydraulic oil, and a pressure of the hydraulic oil by the filter. A pressure loss detection means for detecting a loss and an output reduction means for reducing the output of the hydraulic circuit are provided, and the pressure loss value detected by the pressure loss detection means is equal to or more than a preset value. A hydraulic circuit protection device in a work machine configured to operate an output reduction means based on the above. 2. A work machine comprising a hydraulic circuit provided with a hydraulic actuator that operates based on the supply of hydraulic oil, and a pollution degree detecting means for detecting the degree of pollution in hydraulic oil, and the output of the hydraulic circuit is reduced. To protect the hydraulic circuit in the working machine, which is configured to operate the output reducing means when the pollution degree detected by the pollution degree detecting means exceeds a preset value. apparatus. 3. The working machine according to claim 1, wherein the output reduction means reduces the output of the hydraulic circuit by reducing the rotational speed of the engine that drives the hydraulic pump that serves as the hydraulic source of the hydraulic circuit. Hydraulic circuit protection device. 4. The protection of a hydraulic circuit in a working machine according to claim 1 or 2, wherein the output lowering means lowers an output of the hydraulic circuit by reducing an output horsepower of a hydraulic pump serving as a hydraulic source of the hydraulic circuit. apparatus. 5. The protection of a hydraulic circuit in a working machine according to claim 1 or 2, wherein the output lowering means lowers the output of the hydraulic circuit by reducing the maximum flow rate of a hydraulic pump that is a hydraulic source of the hydraulic circuit. apparatus. 6. The main oil reducer according to claim 1, wherein the output lowering means lowers a set pressure of a main relief valve arranged in a main oil passage extending from a hydraulic pump serving as a hydraulic source of a hydraulic circuit to an oil tank. A protective device for a hydraulic circuit in a work machine that reduces the maximum pressure in the road. 7. The output reduction means according to claim 1 or 2, wherein the set pressure of a pilot circuit relief valve arranged in a pilot oil passage provided in the hydraulic circuit is lowered to lower the maximum pressure of the pilot oil passage. A protective device for a hydraulic circuit in a working machine, which reduces the spool movement amount of a control valve arranged in the hydraulic circuit to control the pressure supply of the hydraulic actuator, thereby reducing the output of the control valve. 8. The protection device for a hydraulic circuit in a working machine according to claim 1, wherein the working machine is provided with a notifying means for notifying based on a detection that the output lowering means operates.