JPH10263332A - Detecting device for clogging of filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a clogging of a filter disposed in a hydraulic oil tank of constructional machine and exactly detect an exchange time of a filter material in a cabin. SOLUTION: For the filter 16, a check valve 21 provided with a relief valve is provided on parallel ton the filter material 20. A switch 24 swtichable by linking with movement of a spool 22 is disposed for the check valve 21 provided with the relief valve. When the filter material 20 is clogged and a pressure an the upstream of the filter 16 rises, the spool 22 of the check valve 21 provided with the relief valve is opened and the switch 24 is switched. When switching of the switch 24 is conducted, a warning display means such as an LED is actuated to inform an aperture of clogging of the filter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting clogging of a filter, and more particularly to an apparatus for judging a time for replacing a filter material in a filter installed in a hydraulic oil tank of a construction machine. is there.

[0002]

Heretofore, the time for replacing the filter material of the filter has been determined by tests and predictions based on actual results. However, in a highly versatile hydraulic shovel, the time until the filter is clogged differs depending on the situation at the work site. Therefore, there is a case where the filter medium which can still be used is replaced or the filter medium is continuously used even after the state where replacement is already required.

[0003] Therefore, there is a technical problem to be solved in order to detect clogging of a filter installed in a hydraulic oil tank of a construction machine and accurately grasp a time for replacing a filter material in a cabin. Thus, the present invention aims to solve this problem.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been proposed to achieve the above object, and is a filter installed in a hydraulic oil tank of a construction machine. A check valve with a relief valve is provided, and a pressure switch for detecting the internal pressure of the return chamber is provided separately from the relief valve.This switches in conjunction with the movement of the spool of the check valve with a relief valve. A switch is provided, and when the spool of the check valve with a relief valve is moved by receiving the upstream pressure of the filter, the switch is switched to activate the warning display means so that the valve opening time can be accurately grasped. An object of the present invention is to provide a device for detecting clogging of a filter.

[0005]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an example of a hydraulic circuit of a construction machine.
2 is pumped up through the strainer 13. The direction and the flow rate of the hydraulic oil pumped by the hydraulic pump 11 are controlled by a direction control valve 14, and an actuator 15 such as a hydraulic cylinder or a hydraulic motor is driven. The hydraulic oil that has passed through the actuator 15
Is returned to, but the filter 16 is installed in the tank 12,
After the contamination in the hydraulic oil is removed by the filter 16, it is returned to the tank 12.

FIGS. 2 and 3 show a main part of the filter 16. An inlet 18 and an outlet 19 are provided in a case 17, and return oil from the actuator 15 flows in from the inlet 18 and passes through the filter medium 20. After the contamination in the oil has been removed, the oil is returned to the tank 12 from the outlet 19.
The filter 16 is provided with an oil passage of a check valve 21 with a relief valve in parallel with the oil passage of the filter medium 20.

The check valve 21 with a relief valve is provided with a switch 23 which is switched by the movement of the spool 22, and the movable piece 23 a of the switch 23 is urged by a spring 24 in a direction in which it contacts the fixed piece 23 b. Have been.
When the upstream pressure and the downstream pressure of the filter 16 are substantially equal,
As shown in the figure, since the spool 22 is in the position where the oil passage is closed by the pressure of the relief spring 25, the switch 2
The contact No. 3 is open, and the warning display means including the LED 26 does not operate.

Here, when a large amount of contamination in oil adheres to the filter medium 20 and causes clogging, the upstream pressure of the filter 16 becomes higher than the downstream pressure, and the upstream pressure becomes higher than the check valve with the relief valve. When the cracking pressure of the valve 21 is reached, the spool 22 moves and opens.

As shown in FIGS. 4 and 5, when the spool 22 of the check valve 21 with the relief valve moves to the open position, the movable piece 23a is pressed by the spring 24 of the switch 23 and comes into contact with the fixed piece 23b. The contact of the switch 23 becomes conductive, and the LED 26 lights up. Therefore, the operator
It is possible to recognize that the filter 16 is clogged by the lighting of 26, and it is possible to accurately grasp the replacement time of the filter medium 20 in the cabin.

Subsequently, when the upstream pressure of the filter 16 further increases and the amount of movement of the spool 22 increases, the movable piece 23a of the switch 23 separates from the spool 22.
When the spring 24 is pressed, the switch 23 maintains a state in which the contacts are conductive.

In this embodiment, the switch 23 is turned on by opening the spool 22 of the check valve 21 with a relief valve, but on the contrary, the check valve with a relief valve is turned on. The switch 23 may be turned off by opening the spool 22 of 21. Further, the warning display means should not be limited to lighting of the LED, but may sound a buzzer or a chime, or warn the operator of the filter clogging by voice.

Here, in the detection circuit shown in FIG. 3, even when the spool 22 of the check valve 21 with a relief valve is opened due to an instantaneous pressure rise, the LED 26 is temporarily turned on. May misjudge. Therefore, as shown in FIG. 6, a signal from the switch 23 may be input to the controller 30, and an output signal to the LED 26 may be controlled based on the determination of the controller 30.

Referring to FIG. 7 and FIG.
When the switch 23 becomes conductive and the switch signal becomes HI, the controller 30 determines whether or not the switch signal HI has been continued for a predetermined time. When the switch signal HI is shorter than the predetermined time n,
The output signal to the LED 26 is set to the LO state, and when the switch signal HI is continued until reaching the predetermined time n, the output signal is set to the L level.
The output signal to the ED 26 is set to the HI state.

That is, due to the instantaneous pressure rise, the switch 2
Even if the switch 3 is turned on, the LED 26 is not turned on. When the switch 23 is turned on continuously for a predetermined time, it is determined that the filter 16 is clogged, and the LED 26 is turned on.
Further, by storing the switch signal to the controller 30, the state of the filter 16 can be grasped by referring to the signal during maintenance, and can be used for investigating the cause of a circuit failure or the like. In a situation where the oil temperature is low immediately after the start of operation, the viscosity is high and the pressure tends to increase.
The state of the filter 16 can be more accurately transmitted to the operator.

The present invention can be variously modified without departing from the spirit of the present invention, and it goes without saying that the present invention extends to the modified ones.

[0016]

As described above, according to the present invention, when the filter installed in the hydraulic oil tank of the construction machine is clogged, the spool of the check valve with a relief valve moves and the switch is turned off. It is configured to be replaced. Since the warning display means is activated by the switching of the switch,
The operator can know exactly when to replace the filter material in the cabin, and the maintenance related to the replacement of the filter material is significantly improved.

[Brief description of the drawings]

 The figure shows an embodiment of the present invention.

FIG. 1 is a diagram illustrating an example of a hydraulic circuit of a construction machine.

FIG. 2 is a circuit diagram of a filter in a state where a filtering material is clean.

FIG. 3 is a cross-sectional view of the filter in a state where the filtering material is clean.

FIG. 4 is a circuit diagram of a filter in which a filter medium is dirty and clogged.

FIG. 5 is a cross-sectional view of a filter in which a filter medium is dirty and clogged.

FIG. 6 is a circuit diagram of a filter to which a controller is added.

FIG. 7 is a flowchart of control of a controller.

FIG. 8 is a timing chart of input / output signals of the controller.

[Explanation of symbols]

 12 tank 16 filter 20 filter material 21 check valve with relief valve 22 spool 23 switch 26 LED

Claims (1)

[Claims] 1. A filter installed in a hydraulic oil tank of a construction machine, wherein a check valve with a relief valve is provided in parallel with a filter material oil path, and the check valve with a relief valve is provided in the filter. A switch that switches in conjunction with the movement of the spool is provided, and when the spool of the check valve with a relief valve moves due to the upstream pressure of the filter, the switch is switched to activate the warning display means. An apparatus for detecting clogging of a filter, comprising: