JP5402875B2 - Construction equipment filter clogging detection device - Google Patents

Description

  The present invention relates to a filter clogging detection device that detects clogging of a filter that filters hydraulic oil in a construction machine such as a hydraulic excavator.

  Conventionally, as this type of device, as disclosed in Patent Document 1, a differential pressure before and after a filter is detected, and when this differential pressure exceeds a set value, it is determined that the device is clogged. Is known.

  In this case, since the kinematic viscosity changes depending on the temperature of the hydraulic oil and affects the differential pressure, it is desirable to manage the hydraulic oil temperature when detecting clogging in order to increase the detection accuracy.

  With regard to this hydraulic oil temperature, in the known technique described in Patent Document 1, the oil temperature is a specified temperature (a temperature suitable for clogging detection, for example, 50 ° C. or higher) according to the hydraulic oil temperature detected by the oil temperature sensor. If the temperature is lower than that, the temperature riser such as an electromagnetic relief valve is operated to heat the hydraulic oil, and the temperature rise process is performed to raise the temperature to a specified temperature.

JP 2004-337668 A

  However, according to the above known technology, the oil temperature may not rise to the specified temperature even when the temperature rise process is performed in cold weather (especially in the winter in cold regions). Misdetection tends to occur.

  Here, it is conceivable that the specified temperature is set low with reference to the time of cold, giving priority to ensuring the detection frequency. However, this deteriorates the detection accuracy under normal temperatures other than during cold weather.

  Accordingly, the present invention provides a filter clogging detection device for a construction machine that can maintain a high detection accuracy at a normal temperature while ensuring a necessary detection frequency even in cold weather.

The invention of claim 1 includes an engine, a hydraulic pump driven by the engine, a hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump, and hydraulic oil discharged from the hydraulic pump to the tank. A filter for a construction machine comprising a filter for filtering at the return line, a pressure detecting means for detecting the pressure acting on the filter, and a control means for detecting clogging based on the pressure detected by the pressure detecting means. In the clogging detection device, an oil temperature detecting means for detecting the temperature of the hydraulic oil is provided, and the control means is
(i) When the hydraulic oil temperature is equal to or higher than a specified temperature as a temperature at which filter clogging detection is to be performed, clogging detection is performed to determine whether the clogged state is present;
(ii) The specified temperature is changed so as to lower the specified temperature at a low temperature than at a high temperature in accordance with an initial oil temperature that is a hydraulic oil temperature before starting the engine.

  According to a second aspect of the present invention, in the configuration of the first aspect, when the initial oil temperature is equal to or higher than a set value, the control means detects clogging when the hydraulic oil temperature becomes equal to or higher than a first specified temperature. When the initial oil temperature is lower than the set value, the clogging is detected when the hydraulic oil temperature becomes equal to or higher than the second specified temperature lower than the first specified temperature.

  According to a third aspect of the present invention, in the configuration of the first or second aspect, the operation unit includes an operation unit that operates the hydraulic actuator, and an operation detection unit that detects whether or not the operation unit is operated. The clogging is detected when the means is not operated.

  According to a fourth aspect of the present invention, in the configuration of the third aspect, the control means is configured to interrupt the clogging detection when the operation means is operated during the clogging detection.

  According to a fifth aspect of the present invention, in the configuration according to any one of the first to fourth aspects, a variable displacement hydraulic pump whose discharge flow rate is controlled by a pump regulator is used as the hydraulic pump. It is configured to detect clogging in a state where a specified flow rate is discharged from the pump.

  A sixth aspect of the present invention is the configuration according to the fifth aspect, wherein the control means is configured to continue the state in which the hydraulic pump discharges the specified flow rate for a predetermined time.

  According to a seventh aspect of the present invention, in the configuration of the fifth or sixth aspect, the control unit includes an operation unit that operates the hydraulic actuator, and an operation detection unit that detects whether or not the operation unit is operated. The clogging detection is performed when the means is not operated, the clogging detection is interrupted when the operation means is operated, and the pump discharge amount corresponding to the operation is commanded to the pump regulator. .

  According to an eighth aspect of the present invention, in the configuration according to any one of the first to seventh aspects, the pressure detection means operates when the differential pressure before and after the filter is equal to or greater than a clogging reference value representing a clogged state. A pressure switch is used, and the control means is configured to determine that the filter is clogged when the differential pressure switch is activated.

  According to a ninth aspect of the present invention, in the configuration of the eighth aspect, the control means is configured to determine that the differential pressure switch is clogged when the operation state of the differential pressure switch continues for a predetermined time.

  According to a tenth aspect of the present invention, in the configuration according to any one of the first to ninth aspects, the control means is configured to detect clogging only once for each on-operation of a key switch for starting the engine. It is a thing.

  According to the present invention, the specified temperature set as the hydraulic oil temperature at which clogging should be detected is changed in a direction to lower than the high temperature at low temperatures according to the initial oil temperature before starting the engine. It is possible to ensure a high frequency of filter clogging detection.

  Moreover, since the specified temperature is raised when the initial oil temperature is high (normal temperature), it is possible to maintain appropriate detection accuracy under normal temperature.

  In this case, the relationship between the initial oil temperature and the specified temperature may be tabulated in advance, and the specified temperature may be continuously changed according to the initial oil temperature. For simplification, the specified temperature may be changed in two ways of the first and second specified temperatures depending on whether the initial oil temperature is equal to or higher than a set value (for example, −5 ° C.).

  According to the third and fourth aspects of the present invention, the clogging is detected when the operation means for operating the hydraulic actuator is not operated, that is, when the operation is stopped. Can do.

  In this case, according to the invention of claim 4, when the operation means is operated during the clogging detection, the clogging detection is interrupted, so that the pressure before and after the filter changes due to the influence of the operation, which may lead to erroneous detection. There is no.

  According to the fifth to seventh aspects of the present invention, since clogging is detected in a state where the specified flow rate is discharged to the hydraulic pump, the detection accuracy can be improved by setting the flow rate suitable for detection as the specified flow rate.

  In this case, according to the invention of claim 6, the specified flow rate is continuously supplied for a certain period of time, so that the detection accuracy is further improved.

  According to the seventh aspect of the present invention, when a configuration is adopted in which clogging detection is performed by flowing a specified flow rate when the operation means is not operated and clogging detection is interrupted when there is an operation, Is returned to the value corresponding to the operation, that is, the normal flow rate control, and there is no possibility that the fine operability is impaired by performing the operation while the flow rate is high.

  According to the inventions of claims 8 and 9, since the on / off type differential pressure switch is used as the pressure detecting means, the cost of the pressure detecting means can be reduced.

  According to the ninth aspect of the present invention, since it is determined that the differential pressure switch is in a clogged state when the differential pressure switch is operated for a certain period of time, the case where the differential pressure switch is temporarily activated due to a cause other than clogging. It can be excluded from the clogging determination and the detection accuracy can be improved.

  According to the invention of claim 10, since the clogging is detected only once for each on-operation of the engine key switch, the clogging is detected particularly when the operation means is not operated and the clogging is detected. Further, it is possible to prevent energy loss caused by detecting clogging more than necessary.

It is a figure which shows the circuit structure and block configuration of the filter clogging detection apparatus which concern on embodiment of this invention. It is a flowchart for demonstrating the clogging detection effect | action by the apparatus. FIG. 3 is a flowchart continued from FIG. 2.

  FIG. 1 shows a circuit configuration and a block configuration of a filter clogging detection device according to an embodiment.

  Reference numeral 1 denotes a variable displacement hydraulic pump driven by an engine 2, and hydraulic oil discharged from the hydraulic pump 1 is hydraulically supplied via a control valve 4 operated by a remote control valve 3 as operating means. The oil is supplied to an actuator (hydraulic cylinder in the illustrated example) 5, and the return oil from the hydraulic actuator 5 is returned to the tank T through the filter 6 via the control valve 4.

  The filter 6 is connected in parallel with a bypass check valve 7 for allowing oil to escape to the tank T when it is completely clogged.

  The discharge flow rate of the hydraulic pump 1 is adjusted by a pump regulator 8, and the pump regulator 8 is controlled by a controller 9 as control means.

  In this apparatus, a difference between an oil temperature sensor (oil temperature detecting means) 10 that detects the temperature of hydraulic oil passing through the filter 6 and a pressure detecting means that operates ON / OFF according to the differential pressure before and after the filter 6. A pressure switch 11 is provided, and an oil temperature signal from the oil temperature sensor 10 and an ON / OFF signal of the differential pressure switch 11 are input to the controller 9.

  The differential pressure switch 11 is turned ON when the differential pressure before and after the filter at a specified flow rate that flows through the filter 6 when clogging is detected is equal to or greater than a clogging reference value that represents the clogging state of the filter 6.

  On the other hand, display means 12 is provided for displaying the result of determination of “normal” and “abnormal” based on a signal from the controller 9 (monitor display and / or buzzer operation), and is controlled as a sensor when the remote control valve 3 is operated. Pressure sensors 13 and 14 are provided as operation detecting means for detecting a pilot pressure sent to the valve 4, and signals from the pressure sensors 13 and 14 are input to the controller 9.

  Since the remote control valve 3 is operated by a lever, hereinafter, the operation of the remote control valve 3 is referred to as a lever operation, and a signal by the lever operation is referred to as a lever signal.

  An on / off signal of an engine key switch 15 for starting / stopping the engine 2 is also input to the controller 9.

  The controller 9 controls the pump regulator 8 based on the on / off signal of the engine key switch 15, the signals from the pressure sensors 13 and 14, and the on / off signal from the differential pressure switch 11 to clog the filter 6. Perform detection.

  The operation of this point will be described with reference to the flowcharts of FIGS.

  As shown in FIG. 2, when the engine key switch 15 is turned on (engine start operation), the initial oil temperature Ti, which is the hydraulic oil temperature before starting the engine, is detected and stored in step S1.

  In step S2, it is determined whether or not the initial oil temperature Ti is equal to or higher than a set value (for example, −5 ° C.). When the initial oil temperature Ti is equal to or higher than the set value, The specified temperature Tr is set to the first specified temperature (for example, 50 ° C.), and the specified temperature Tr is set to the second specified temperature (for example, 30 ° C.) when it is less than the set value.

  In step S3, it is determined whether or not the current hydraulic oil temperature has reached the specified temperature Tr. If NO, the determination of clogging should not be performed yet, so that the determination possible flag that enables clogging determination in step S4 is possible. Is turned off.

  On the other hand, if YES, it is determined whether or not there is no lever operation in step S5. If NO (with lever operation), it is determined that clogging should not be determined during work, and step S4 (determination flag OFF). Move on.

  On the other hand, in the case of YES (no lever operation), since the clogging determination may be performed because the work is not being performed, the determination possible flag is set to ON.

  As a continuation of steps S4 and S6, as shown in FIG. 3, it is determined whether or not the determinable flag is ON in step S7, and counting of a determination timer (time for continuously detecting clogging) is started in step S8. At the same time, the pump discharge amount is set to a prescribed flow rate suitable for clogging detection (for example, the maximum pump discharge amount), and commanded to the pump regulator 8.

  In step S9, it is determined whether or not the differential pressure switch 11 is ON. If YES, counting of the time during which the ON state of the differential pressure switch 11 continues is started in step S10.

  Subsequently, in steps S11 and S12, it is determined whether or not the determination timer and the differential pressure switch ON time have passed the respective set times. If both are YES, it is determined that the filter is clogged (abnormal). .

  On the other hand, if NO in step S12 (differential pressure switch ON time has not reached the set time), it is determined in step S14 that it is not clogged (normal).

  In step S15, a “determination completed” flag is set, and the determination timer and the differential pressure switch ON time are reset.

  Next, the determination result of “normal” or “abnormal” is displayed by the display means 12 in step S16, and the filter clogging detection is completed.

  If NO in steps S7 and S11, the process returns to step S3. If NO in step S9 (differential pressure switch OFF), the process proceeds to step S11.

  In this way, since the specified temperature Tr as the hydraulic oil temperature to be detected for clogging is changed in a direction to lower than the high temperature at a low temperature according to the initial oil temperature Ti before starting the engine, a filter necessary even at a cold time is required. The clogging detection frequency can be ensured.

  In addition, when the initial oil temperature Ti is high (in the case of the normal temperature), the specified temperature is raised, so that the detection accuracy can be increased under the normal temperature.

  That is, it is possible to maintain high detection accuracy under normal temperature while ensuring the necessary detection frequency even in cold weather.

  Note that when the initial oil temperature Ti is lower than the set value, the specified temperature Tr becomes the second specified temperature lower than the first specified temperature, so the detection accuracy is lower than when the specified temperature Tr is the first specified temperature. According to the setting of 2 normal temperature = 30 ° C. exemplified in the above description, it is possible to suppress the detection error to an extent that the detection error can be actually realized while ensuring the necessary detection frequency.

  Further, according to this apparatus, the following effects can be obtained.

  (I) Since the clogging is detected when the remote control valve 3 is not operated, that is, when the operation is stopped, the clogging of the filter can be detected within a range that does not hinder the operation.

  (II) In this case, if the remote control valve 3 is operated while clogging is being detected (while NO in step S11 of FIG. 3), NO is determined in step S5 of FIG. 2, and the determination possible flag is set in step S4. Since the clogging detection is interrupted and the clogging detection is interrupted, there is no possibility that the pressure before and after the filter changes due to the operation and the erroneous detection is caused.

  (III) When the clogging detection is interrupted, the pump discharge amount returns to the value corresponding to the operation, that is, the normal flow rate control, so there is no possibility that the fine operability is impaired by performing the operation while the flow rate is high. .

  (IV) Since clogging is detected in a state in which the specified flow rate is discharged to the hydraulic pump 1 (step S8 in FIG. 3), the detection accuracy can be improved by setting the flow rate suitable for detection as the specified flow rate. .

  (V) In this case, the specified flow rate is continuously supplied for a certain time (step S11), so that the detection accuracy is further improved.

  (VI) Since the on / off type differential pressure switch 11 is used as the pressure detecting means, the cost of the pressure detecting means can be reduced.

  (VII) Since it is determined that the differential pressure switch 11 is in a clogged state when the differential pressure switch 11 is operated for a certain time (step S13), the case where the differential pressure switch 11 is temporarily activated due to a cause other than clogging is considered. It can be excluded from the clogging determination and the detection accuracy can be improved.

  (VIII) In order to set the determined flag in step S15 of FIG. 3, that is, to detect clogging only once for each ON operation of the engine key switch 15, the non-control of the remote control valve 3 is particularly performed as in the embodiment. When a configuration is adopted in which clogging detection is performed by supplying a specified flow rate during operation, energy loss due to clogging detection being performed at each non-operation time can be prevented.

Other embodiments
(1) To prevent the clogging detection frequency from becoming excessive, the elapsed time from the previous clogging detection may be measured, and clogging may be detected on the condition that a certain time has elapsed.

  (2) In the above embodiment, clogging is detected only once by one operation of the engine key switch, and it is concluded that the state is clogged when “abnormal” is judged by this one detection action. Although the configuration is adopted, it is concluded that the state is clogged only when the determination of “abnormal” is made continuously by the detection action by the engine key switch ON operation a plurality of times (for example, three times). You may take

  (3) In the above embodiment, the initial oil temperature is changed between the first and second specified temperatures in two ways of whether the initial oil temperature is equal to or higher than the set value, but the initial oil temperature is changed in three ways. The temperature range may be divided into the above temperature ranges, and the specified temperature may be changed among three or more corresponding to this temperature range.

  Alternatively, as described above, the relationship between the initial oil temperature and the specified temperature may be tabulated in advance, and the specified temperature may be continuously changed according to the initial oil temperature.

  (4) In the above embodiment, only whether or not the clogged state is determined and displayed, but the pressure sensor is used as the pressure detecting means to detect the differential pressure, and based on this differential pressure, the “clogged state The degree of clogging including “” may be determined and the degree of clogging may be displayed sequentially or at an appropriate time.

1 Hydraulic pump 2 Engine 3 Remote control valve (operating means)
4 Control valve 5 Hydraulic cylinder (hydraulic actuator)
6 Filter 8 Pump regulator 9 Controller (control means)
10 Oil temperature sensor (oil temperature detection means)
11 Differential pressure switch (pressure detection means)
12 Display means 13, 14 Pressure sensor (operation detection means)
15 Engine key switch

Claims (10)

An engine, a hydraulic pump driven by the engine, a hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump, and a filter for filtering the hydraulic oil discharged from the hydraulic pump through a return line to the tank In the filter clogging detection apparatus for a construction machine, comprising the pressure detection means for detecting the pressure acting on the filter and the control means for detecting clogging based on the pressure detected by the pressure detection means, the above operation Oil temperature detection means for detecting the temperature of the oil is provided, the control means,
(i) When the hydraulic oil temperature is equal to or higher than a specified temperature as a temperature at which filter clogging detection is to be performed, clogging detection is performed to determine whether the clogged state is present;
(ii) A construction machine configured to change the specified temperature in a direction to lower the specified temperature at a low temperature than at a high temperature according to an initial oil temperature that is a hydraulic oil temperature before starting the engine. Filter clogging detection device.   When the initial oil temperature is equal to or higher than the set value, the control means detects clogging when the hydraulic oil temperature is equal to or higher than the first specified temperature, and when the initial oil temperature is lower than the set value, the hydraulic oil temperature is detected. 2. The filter clogging detection device for a construction machine according to claim 1, wherein clogging is detected when the temperature reaches a second specified temperature lower than the first specified temperature.   An operation means for operating the hydraulic actuator and an operation detection means for detecting whether or not the operation means is operated, and the control means is configured to detect clogging when the operation means is not operated. The filter clogging detection device for construction machinery according to claim 1 or 2.   4. The filter clogging detection apparatus for a construction machine according to claim 3, wherein the control means is configured to interrupt clogging detection when the operation means is operated during clogging detection.   As the hydraulic pump, a variable displacement hydraulic pump whose discharge flow rate is controlled by a pump regulator is used, and the control means is configured to detect clogging in a state where the hydraulic pump discharges a specified flow rate. The filter clogging detection device for a construction machine according to any one of claims 1 to 4, wherein the filter clogging detection device is used.   6. The filter clogging detection device for a construction machine according to claim 5, wherein the control means is configured to continue the state in which the specified flow rate is discharged to the hydraulic pump for a predetermined time.   An operation means for operating the hydraulic actuator; and an operation detection means for detecting whether or not the operation means is operated. The control means detects clogging when the operation means is not operated. The clogging detection of a construction machine according to claim 5 or 6, characterized in that the clogging detection is interrupted when there is, and the pump discharge amount is commanded to the pump regulator according to the operation. apparatus.   As the pressure detecting means, a differential pressure switch that operates when the differential pressure before and after the filter is equal to or higher than a clogging reference value indicating a clogged state is used, and the control means performs a filter operation when the differential pressure switch is activated. The filter clogging detection device for a construction machine according to any one of claims 1 to 7, wherein the filter is determined to be in a clogged state.   9. The filter clogging detection device for a construction machine according to claim 8, wherein the control means is configured to determine that the differential pressure switch is in a clogged state when an operation state of the differential pressure switch continues for a predetermined time. .   The said control means is comprised so that clogging may be detected only once per one ON operation of the key switch which starts the said engine, The one of Claims 1-9 characterized by the above-mentioned. Filter clogging detection device for construction machinery.

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