Construction machine

Abstract

The invention provides a construction machine capable of prolonging the replacement interval of hydraulic oil. A hydraulic shovel comprises: an additive tank for storing an additive; an additive supply line for supplying an additive from the additive tank to the working oil tank; an on-off valve disposed in the additive supply line and switching between a closed state and an open state; an oxidation degree sensor for detecting the oxidation degree of the hydraulic oil; and a controller. When the rate of change in the degree of oxidation of the hydraulic oil is equal to or greater than a predetermined value, the controller executes control for notifying the content of switching the on-off valve to the open state or control for switching the on-off valve to the open state. The controller executes control for reporting the content of switching the on-off valve to the open state or control for switching the on-off valve to the open state when the machine operation time from the time when the hydraulic oil is replaced or the machine operation time from the time when the on-off valve is switched from the open state to the closed state is equal to or greater than a predetermined value.

Description

Technical Field

[0001] The present invention relates to engineering machinery such as hydraulic excavators and wheel loaders. Background Art

[0002] The construction machinery includes: a working oil tank storing working oil; a hydraulic pump driven by an engine or an electric motor to pressurize the working oil in the working oil tank; a hydraulic actuator for operation or travel; and a control valve for controlling the supply of working oil from the hydraulic pump to the hydraulic actuator and the discharge of working oil from the hydraulic actuator to the working oil tank. The control valve is operated, for example, according to the operation of the operating lever by the driver, and the hydraulic actuator is driven.

[0003] The working oil of construction machinery is composed of base oil and additives. Base oil is obtained by refining crude oil, and mineral oil is mainly used. Additives improve the quality of working oil and are antioxidants, etc.

[0004] However, Patent Document 1 discloses a dispensing device for dispensing additives to a fuel circulation circuit of an internal combustion engine of an automobile in order to improve the fuel quality of the internal combustion engine of the automobile. The dispensing device includes: an additive tank that stores the additive; an additive dispensing channel that distributes the additive from the additive tank to the fuel circulation circuit; and an actuator that can close the additive dispensing channel. Furthermore, the additive dispensing channel is closed, for example, when the internal combustion engine is stopped or when the viscosity of the additive becomes high and the additive dispensing channel may be clogged. In addition, for example, during the operation of the internal combustion engine, the concentration of the additive relative to the fuel is adjusted by making the opening frequency or opening time of the additive dispensing channel variable.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application No. 2014-524534 Summary of the invention

[0008] Problems to be solved by the invention

[0009] The working oil of construction machinery is increasingly degraded by oxidation due to the influence of heat generated by changes in pressure and flow. This oxidation degradation reduces the lubrication performance of the working oil due to the consumption of antioxidants and the deterioration of base oil in the working oil. In addition, the reduction in the lubrication performance of the working oil may cause damage to important internal equipment and loss of function, so the working oil needs to be replaced regularly.

[0010] As a structure for achieving a longer interval between oil changes, the inventors of the present application have considered providing an additive tank storing additives such as antioxidants, an additive supply line for supplying additives from the additive tank to the oil tank, and an on-off valve disposed on the additive supply line. By switching the on-off valve from a closed state to an open state, additives are supplied from the additive tank to the oil tank via the additive supply line. This can suppress a decrease in the concentration of additives in the oil and suppress deterioration of the oil.

[0011] If the additive supply timing is too late, the working oil deteriorates more rapidly, and if the additive supply timing is too early, the additive is consumed faster and the additive replenishment interval is shortened. Therefore, it is preferable to appropriately notify or control the additive supply timing, that is, the timing of opening the on-off valve.

[0012] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a construction machine capable of extending the replacement interval of hydraulic oil.

[0013] Means for solving problems

[0014] In order to achieve the above-mentioned purpose, the engineering machinery of the present invention comprises: a working oil tank for storing working oil; a hydraulic pump for pressurizing the working oil in the working oil tank; a hydraulic actuator; and a control valve for controlling the supply of working oil from the hydraulic pump to the hydraulic actuator and the discharge of working oil from the hydraulic actuator to the working oil tank, the engineering machinery comprises: an additive tank for storing additives; an additive supply pipeline for supplying additives from the additive tank to the working oil tank; an on-off valve, which is arranged on the additive supply pipeline and switches between a closed state and an open state, in which the supply of additives from the additive tank to the working oil tank is blocked in the closed state, and in which the supply of additives from the additive tank to the working oil tank is carried out in the open state; an oxidation degree sensor A sensor for detecting the degree of oxidation of the working oil; and a controller for calculating the rate of change of the degree of oxidation of the working oil based on the detection result of the oxidation sensor, and executing control of notifying the switching of the on-off valve to the open state or the switching of the on-off valve to the open state when the rate of change of the degree of oxidation of the working oil is above a specified value, and executing control of notifying the switching of the on-off valve to the open state or the switching of the on-off valve to the open state when the rate of change of the degree of oxidation of the working oil is below a specified value and the mechanical operating time since the working oil was replaced or the mechanical operating time since the on-off valve was switched from the open state to the closed state is above a specified value, executing control of notifying the switching of the on-off valve to the open state or the switching of the on-off valve to the open state.

[0015] Effects of the Invention

[0016] According to the present invention, it is possible to extend the replacement interval of the hydraulic oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a side view showing the structure of the hydraulic excavator in the first embodiment of the present invention.

[0018] Figure 2 This is a diagram showing the configuration of a drive device for a hydraulic excavator according to a first embodiment of the present invention together with related equipment.

[0019] Figure 3 This is a flowchart showing the processing contents of the controller in the first embodiment of the present invention.

[0020] Figure 4 This is a graph showing the relationship between the density and the total acid number of the hydraulic oil in the first embodiment of the present invention.

[0021] Figure 5 These are diagrams showing examples of additives and their effects in the first embodiment of the present invention.

[0022] Figure 6 This is a graph showing changes in the total acid value of hydraulic oil in the first embodiment of the present invention and in the prior art.

[0023] Figure 7 It is a graph showing the relationship between the added concentration of the antioxidant and the degradation suppression effect and the relationship between the added concentration of the antioxidant and the wear amount of the sliding portion in the second embodiment of the present invention.

[0024] Figure 8 It is a graph showing the relationship between the added concentration of tricresyl phosphate and the amount of wear of the sliding portion and the relationship between the added concentration of tricresyl phosphate and the amount of corrosion of the sliding portion in the second embodiment of the present invention.

[0025] Fig. 9 It is a graph showing the relationship between the addition concentration of dioleyl hydrogen phosphite and the amount of wear of the sliding part and the relationship between the addition concentration of dioleyl hydrogen phosphite and the amount of corrosion of the sliding part in the second embodiment of the present invention.

[0026] Fig.10 It is a figure which shows the Example of the additive in the 2nd Embodiment of this invention and its effect.

[0027] Fig.11 It is a figure which shows the Example of the additive in the 2nd Embodiment of this invention and its effect.

[0028] Fig.12 This is a diagram showing the configuration of a drive device for a hydraulic excavator according to a modified example of the present invention together with related equipment.

[0029] Fig.13This is a graph showing the relationship between the dielectric constant and the total acid number of the hydraulic oil in another modified example of the present invention. DETAILED DESCRIPTION

[0030] A first embodiment of the present invention will be described with reference to the drawings, taking a hydraulic excavator as an example to which the present invention is applied.

[0031] Figure 1 It is a side view showing the structure of the hydraulic excavator in this embodiment.

[0032] The hydraulic excavator of this embodiment includes a traveling body 1 that can travel, a revolving body 2 that is rotatably provided on the upper side of the traveling body 1, and a front side ( Figure 1 The vehicle body is composed of a traveling body 1 and a revolving body 2. The traveling body 1 travels by the rotation of a traveling motor 4, and the revolving body 2 revolves by the rotation of a revolving motor (not shown).

[0033] The working device 3 includes a boom 5 rotatably connected to the front side of the revolving body 2, an arm 6 rotatably connected to the front end of the boom 5, and a bucket 7 rotatably connected to the front end of the arm 6. The boom 5 is rotated by extending and retracting the boom cylinder 8, the arm 6 is rotated by extending and retracting the arm cylinder 9, and the bucket 7 is rotated by extending and retracting the bucket cylinder 10.

[0034] The revolving body 2 includes a cab 11 in which a driver can sit and a machine room 12 formed in a portion other than the cab 11. The cab 11 is provided with a plurality of operating devices (not shown) that can be operated by the driver and a monitor 13 (see the following description). Figure 2 ) The monitor 13 includes, for example, a display for displaying messages and the like and keys for inputting numerical values ​​and the like.

[0035] The hydraulic excavator of the present embodiment includes a drive device that drives a plurality of hydraulic actuators (specifically, the travel motor 4 , swing motor, boom cylinder 8 , arm cylinder 9 , and bucket cylinder 10 ) in response to operations of a plurality of operating devices. Figure 2 FIG. 1 is a diagram showing the structure of the driving device of the hydraulic excavator in this embodiment together with related equipment. Figure 2 Only the structure related to the boom cylinder 8 among the structures of the driving device is shown.

[0036] The drive device of this embodiment includes: a working oil tank 14, which stores working oil; a hydraulic pump 16, which is driven by an engine 15 to pressurize the working oil in the working oil tank 14; a control valve 17, which operates in response to the operation of the operating device and controls the supply of working oil from the hydraulic pump 16 to the boom cylinder 8 and the discharge of working oil from the boom cylinder 8 to the working oil tank 14; and an air-cooled or water-cooled cooler 19, which is arranged in a discharge line 18 that discharges working oil from the control valve 17 to the working oil tank 14, and cools the working oil. The above-mentioned equipment is arranged in the machine room 12 of the revolving body 2.

[0037] The working oil tank 14 includes: a breather 20 that takes in external air into the tank and adjusts the pressure in the tank to the external air pressure; an air filter 21 that is connected to the breather 20 and removes foreign matter from the external air; and an oil filter 22 that is connected to the hydraulic pump 16 and the cooler 19 and removes foreign matter such as sludge from the working oil. The capacity of the working oil tank 14 is, for example, 200L.

[0038] The hydraulic oil stored in the hydraulic oil tank 14 is composed of base oil and additives. The base oil is mineral oil. The viscosity grade of the hydraulic oil is, for example, VG46.

[0039] The additives contained in the working oil are, for example, antioxidants, extreme pressure agents (load-resistant additives), detergent dispersants, viscosity index improvers, defoamers and demulsifiers. As antioxidants, zinc dithiophosphates, organic sulfur compounds, hindered phenols or aromatic amines are used. As extreme pressure agents, higher fatty acids, higher alcohols, phosphates, phosphites or thiophosphates are used. As detergent dispersants, organic acid metal compounds, neutral / high alkaline metals, high alkaline metal sulfonates, high alkaline metal phenolates, high alkaline metal sulfonates, succinimide, succinates or benzylamine are used. As viscosity index improvers, polymethacrylates, olefin copolymers, styrene olefin copolymers or polyisobutylene are used. As defoamers, polymethylsiloxanes, silicates, organic fluorine compounds, metal soaps, fatty acid esters, phosphates, higher alcohols or polyalkylene glycols are used. As demulsifiers, ethylene oxide adducts, ethylene oxide / propylene oxide block polymers or quaternary ammonium salts are used.

[0040] The working oil is further degraded by oxidation due to the heat generated when pressure is applied or when pressure is released. In detail, the base oil constituting the working oil is mainly composed of hydrocarbons. Due to the thermal decomposition of hydrocarbons, hydrocarbon radicals are generated, and the hydrocarbon radicals combine with oxygen to form peroxy radicals. Then, the peroxy radicals combine with the undecomposed base oil, hydroxyl radicals, etc., and finally become carboxylic acids through alcohols and aldehydes. In addition, when the carboxylic acid increases and the total acid value of the working oil becomes higher, that is, when the oxidative degradation of the working oil is aggravated, the antioxidants contained in the working oil are consumed, and corrosion and dissolution of hydraulic equipment and piping may be caused. Therefore, it is necessary to regularly replace the working oil stored in the working oil tank 14.

[0041] As a structure for achieving a prolonged interval between working oil replacement, the hydraulic excavator of this embodiment includes: an additive tank 23, which is arranged near the working oil tank 14 and stores additives; an additive supply pipeline 24, which supplies additives from the additive tank 23 to the working oil tank 14; an on-off valve 25, which is arranged on the additive supply pipeline 24 and switches between a closed state and an open state; a flow meter 26, which is arranged on the additive supply pipeline 24 and detects and displays the flow rate of the additive; an oxidation degree sensor 27, which is arranged on the downstream side of the cooler 19 in the above-mentioned discharge pipeline 18 and detects the degree of oxidation of the working oil (oxidation degree); and a controller 28.

[0042] The on-off valve 25 is normally in an open state to block the supply of additive from the additive tank 23 to the hydraulic oil tank 14. The on-off valve 25 is electrically or manually switched to a closed state to supply additive from the additive tank 23 to the hydraulic oil tank 14.

[0043] The additive tank 23 stores additives in a manner such as dissolving additives in a base oil with a viscosity grade of VG46 at a concentration of 10% by weight. The additive is an antioxidant, such as zinc dithiophosphate, an organic sulfur compound, a hindered phenol or an aromatic amine. Diphenylamine and / or 2,6-di-tert-butyl-p-cresol are particularly preferred. The capacity of the additive tank 23 is, for example, 10 L.

[0044] Although not shown, the controller 28 includes a processor that executes processing according to a program and a memory that stores programs and data. The controller 28 controls the monitor 13 and the on-off valve 25 based on the detection result of the oxidation degree sensor 27. Figure 3 The processing contents of the controller 28 will be described. Figure 3 This is a flowchart showing the processing contents of the controller in this embodiment.

[0045] In step S1, the controller 28 calculates the rate of change of the degree of oxidation of the hydraulic oil based on the detection result of the degree of oxidation sensor 27. Specifically, the degree of oxidation sensor 27 of the present embodiment is a density sensor that detects the density of the hydraulic oil. The controller 28 calculates the difference between the current density detection value and the previous density detection value, and calculates the rate of change of the density by dividing the difference by the previous density detection value.

[0046] Here, the reason for detecting the density of the hydraulic oil and calculating its rate of change is explained. As an indicator of the degree of oxidation of the hydraulic oil, there is the total acid value of the hydraulic oil, but it is difficult to measure this value. However, it is known that when the hydraulic oil deteriorates due to oxidation, oxygen is introduced into the molecular structure, and the density increases. That is, Figure 4 As shown, the density of the hydraulic oil is proportional to the total acid number. Therefore, the density of the hydraulic oil corresponding to the total acid number of the hydraulic oil is detected and its change rate is calculated. The change rate of the hydraulic oil density refers to the change rate of the oxidation degree of the hydraulic oil.

[0047] In step S2, the controller 28 determines whether the rate of change of the oxidation degree of the hydraulic oil is equal to or greater than a predetermined value (eg, 0.05%), thereby determining whether the rate of progress of oxidation degradation of the hydraulic oil is equal to or greater than an assumed value.

[0048] If the rate of change of the degree of oxidation of the hydraulic oil is greater than or equal to the predetermined value in step S2, the process proceeds to step S3. In step S3, the controller 28 causes the monitor 13 to display a message indicating that the on-off valve 25 should be opened (i.e., switched to the open state) and a message prompting an input of whether to automatically open the on-off valve 25. Then, the process proceeds to step S4, where the controller 28 determines whether an input of automatically opening the on-off valve 25 has been made on the monitor 13.

[0049] When the input of not automatically opening the on-off valve 25 is performed on the monitor 13 in step S4, the process ends. The driver manually switches the on-off valve 25 from the closed state to the open state. Thus, the additive is supplied from the additive tank 23 to the working oil tank 14 via the additive supply line 24. The driver confirms the supply amount of the additive based on the flow rate of the additive displayed on the flow meter 26. And, if the supply amount of the additive reaches the expected value, the driver manually switches the on-off valve 25 from the open state to the closed state.

[0050] On the other hand, when the input of automatically opening the on-off valve 25 is made on the monitor 13 in step S4, the process proceeds to step S5. In step S5, the controller 28 causes the monitor 13 to display a message prompting the input of whether to change the supply amount of the additive. Then, it is determined whether the input of changing the supply amount of the additive is made on the monitor 13.

[0051] If the content of not changing the supply amount of the additive is input on the monitor 13 in step S5, the process proceeds to step S6. In step S6, the controller 28 switches the on-off valve 25 from the closed state to the open state. Thus, the additive is supplied from the additive tank 23 to the working oil tank 14 via the additive supply line 24. Then, the controller 28 calculates the supply amount of the additive based on the detection result of the flow meter 26, and switches the on-off valve 25 from the open state to the closed state if the supply amount of the additive reaches the set value.

[0052] On the other hand, when the content of changing the supply amount of the additive is input on the monitor 13 and the change value of the supply amount of the additive is input in step S5, the process proceeds to step S7. In step S7, the controller 28 switches the on-off valve 25 from the closed state to the open state. Thus, the additive is supplied from the additive tank 23 to the working oil tank 14 via the additive supply line 24. Then, the controller 28 calculates the supply amount of the additive based on the detection result of the flow meter 26, and switches the on-off valve 25 from the open state to the closed state if the supply amount of the additive reaches the change value.

[0053] When the rate of change of the degree of oxidation of the hydraulic oil is lower than the predetermined value in step S2, the process proceeds to step S8. In step S8, the controller 28 determines whether the mechanical operation time from when the hydraulic oil is replaced or the mechanical operation time from when the on-off valve 25 is switched from the open state to the closed state (in other words, the accumulated driving time of the engine 15) is greater than a predetermined value (e.g., 2000 hours).

[0054] If the machine operation time is less than the predetermined value in step S8, the process ends. On the other hand, if the machine operation time is greater than the predetermined value, the process proceeds to step S3. Then, the above-mentioned process is performed.

[0055] As described above, in this embodiment, the additive is supplied from the additive tank 23 to the hydraulic oil tank 14 via the additive supply line 24, thereby suppressing a decrease in the concentration of the additive in the hydraulic oil and suppressing hydraulic oil degradation. Therefore, the hydraulic oil replacement interval can be extended.

[0056] In addition, in this embodiment, when the rate of change of the oxidation degree of the hydraulic oil is greater than a predetermined value, the timing of supplying the additive is notified or controlled. In addition, when the rate of change of the oxidation degree of the hydraulic oil is less than a predetermined value, the timing of supplying the additive is notified or controlled when the machine operation time reaches a predetermined value. Therefore, it is possible to suppress the deterioration of the hydraulic oil and to extend the interval of supplying the additive.

[0057] use Figure 5 and Figure 6 The following describes an embodiment of the additive stored in the additive tank 23 and its effect. Figure 5As shown, Example 1 of the additive is diphenylamine, Example 2 of the additive is 2,6-di-tert-butyl-p-cresol, and Example 3 of the additive is diphenylamine and 2,6-di-tert-butyl-p-cresol. Figure 6 As shown, in the prior art (in other words, when the additive is not supplied to the working oil tank 14), if the machine operation time increases, the total acid value of the working oil increases significantly. On the other hand, in the present embodiment, even if the machine operation time increases, the increase in the total acid value of the working oil can be suppressed. Therefore, the replacement interval of the working oil can be set to 2.1 to 2.3 times compared with the prior art. It should be noted that the added concentration of the antioxidant relative to the working oil is, for example, in the range of 0.1 to 0.3 wt%.

[0058] A second embodiment of the present invention will be described. In this embodiment, the same reference numerals are used for the same parts as those in the first embodiment, and description thereof will be omitted as appropriate.

[0059] The extreme pressure agent contained in the working oil forms a film by reacting on the surface of the sliding part (metal) of the hydraulic equipment to suppress the wear of the sliding part. However, the extreme pressure agent and the like are consumed due to the long-term use of the working oil. In addition, if an antioxidant is supplied to the working oil tank 14 as in the first embodiment, the wear suppression effect of the extreme pressure agent is reduced due to the reaction with the antioxidant. Therefore, in this embodiment, the additives stored in the additive tank 23 are an antioxidant and an extreme pressure agent, and the antioxidant and the extreme pressure agent are supplied to the working oil tank 14.

[0060] As the antioxidant, for example, zinc dithiophosphate, an organic sulfur compound, a hindered phenol, or an aromatic amine is used, and diphenylamine and / or 2,6-di-tert-butyl-p-cresol are particularly preferred.

[0061] The antioxidant is preferably added at a concentration of 0.1 to 0.3 wt % relative to the working oil. Figure 7 The reason is explained. If the added concentration of the antioxidant is lower than 0.3wt%, the degradation inhibition effect increases as the added concentration of the antioxidant increases, but if the added concentration of the antioxidant is greater than 0.3wt%, the degradation inhibition effect is approximately constant regardless of whether the added concentration of the antioxidant increases or not. On the other hand, as the added concentration of the antioxidant increases, the wear inhibition effect decreases and the amount of wear of the sliding part increases. In order to increase the degradation inhibition effect to above the specified required value and suppress the amount of wear of the sliding part to below the specified required value, the added concentration of the antioxidant relative to the working oil is preferably in the range of 0.1 to 0.3wt%.

[0062] As the extreme pressure agent, for example, phosphate, phosphite or thiophosphate is used, and tricresyl phosphate and / or dioleyl hydrogen phosphite are particularly preferred.

[0063] When only tricresyl phosphate is supplied as an extreme pressure agent, the concentration of tricresyl phosphate added to the hydraulic oil is preferably in the range of 0.5 to 1.5 wt %. Figure 8 The reason is explained. If the added concentration of tricresyl phosphate is lower than 0.5wt%, the amount of wear of the sliding part decreases sharply as the added concentration of tricresyl phosphate increases, but if the added concentration of tricresyl phosphate is greater than 0.5wt%, the amount of wear of the sliding part decreases slowly as the added concentration of tricresyl phosphate increases. On the other hand, the amount of corrosion of the sliding part increases as the added concentration of tricresyl phosphate increases. In order to suppress the amount of wear of the sliding part to below the prescribed required value and suppress the amount of corrosion of the sliding part to below the prescribed required value, it is preferred that the added concentration of tricresyl phosphate relative to the working oil is in the range of 0.5 to 1.5wt%.

[0064] When only dioleyl hydrogen phosphite is supplied as an extreme pressure agent, the addition concentration of dioleyl hydrogen phosphite relative to the working oil is preferably in the range of 0.1 to 1.0 wt %. Fig. 9 The reason is explained. If the addition concentration of dioleyl hydrogen phosphite is lower than 0.1wt%, the amount of wear of the sliding part decreases sharply as the addition concentration of dioleyl hydrogen phosphite increases, but if the addition concentration of dioleyl hydrogen phosphite is 0.1wt% or more, the amount of wear of the sliding part decreases slowly as the addition concentration of dioleyl hydrogen phosphite increases. On the other hand, the amount of corrosion of the sliding part increases as the addition concentration of dioleyl hydrogen phosphite increases. In order to suppress the amount of wear of the sliding part to below the prescribed required value and suppress the amount of corrosion of the sliding part to below the prescribed required value, it is preferred that the addition concentration of dioleyl hydrogen phosphite relative to the working oil is in the range of 0.1 to 1.0wt%.

[0065] In this embodiment, as in the first embodiment, by supplying the additive from the additive tank 23 to the working oil tank 14 via the additive supply line 24, it is possible to suppress the concentration of the additive in the working oil from decreasing and suppress the deterioration of the working oil. Therefore, it is possible to extend the replacement interval of the working oil. In addition, it is possible to extend the replenishment interval of the additive.

[0066] use Fig.10 and Fig.11 The following describes an embodiment of the additive stored in the additive tank 23 and its effect. Fig.10 and Fig.11As shown, Example 4 of the additive is diphenylamine and tricresyl phosphate, Example 5 of the additive is diphenylamine, 2,6-di-tert-butyl-p-cresol and tricresyl phosphate, Example 6 of the additive is diphenylamine and dioleyl hydrogen phosphite, and Example 7 of the additive is diphenylamine, 2,6-di-tert-butyl-p-cresol and dioleyl hydrogen phosphite. Compared with the prior art, the replacement interval of the working oil can be set to 2.1 to 2.3 times. In addition, the wear and corrosion of the sliding part of the hydraulic equipment can be suppressed.

[0067] It should be noted that, in the second embodiment, the hydraulic excavator is described as having an additive tank 23 storing an antioxidant and an extreme pressure agent, but the present invention is not limited thereto. Fig.12 As shown in the modified example, the hydraulic excavator may also include an additive tank 23 storing an antioxidant and an additive tank 23A storing an extreme pressure agent. The hydraulic excavator of this modified example further includes an additive supply line 24A for supplying the extreme pressure agent from the additive tank 23A to the working oil tank 14, an on-off valve 25A disposed on the additive supply line 24A and switching between a closed state and an open state, and a flow meter 26A disposed on the additive supply line 24A and detecting and displaying the flow rate of the extreme pressure agent. The controller 28 causes the monitor 13 to display a message that the on-off valves 25 and 25A should be opened (i.e., switched to an open state) and a message prompting input whether to automatically open the on-off valves 25 and 25A. And, when the content of automatically opening the on-off valves 25 and 25A is input on the monitor 13, the on-off valves 25 and 25A are temporarily opened (i.e., switched to an open state). In this modified example, the addition concentration of the antioxidant and the addition concentration of the extreme pressure agent can be changed separately.

[0068] In the first embodiment, the second embodiment and their variations, the oxidation degree sensor 27 is described as a density sensor for detecting the density of the hydraulic oil, but the invention is not limited thereto. It is known that when the hydraulic oil deteriorates due to oxidation, oxygen is introduced into the molecular structure and the dielectric constant increases. Fig.13 As shown, the dielectric constant of the working oil is proportional to the total acid number. Therefore, the oxidation degree sensor 27 may also be a dielectric constant sensor that detects the dielectric constant of the working oil. In this case, the controller 28 may calculate the change rate of the dielectric constant of the working oil as the change rate of the oxidation degree of the working oil.

[0069] In the first embodiment, the second embodiment and the modified example thereof, the controller 28 displays a message on the monitor 13 notifying that the on-off valve should be opened (i.e., switched to the open state), but the present invention is not limited thereto. The controller 28 may output a sound notifying that the on-off valve should be opened (i.e., switched to the open state) through a speaker, for example.

[0070] In addition, in the first embodiment, the second embodiment and the modified example thereof, the controller 28 performs two kinds of control, namely, the control of notifying that the on-off valve should be opened (i.e., switched to the open state) and the control of temporarily opening the on-off valve (i.e., switched to the open state), but the present invention is not limited thereto. The controller 28 may perform only one of the control of notifying that the on-off valve should be opened (i.e., switched to the open state) and the control of temporarily opening the on-off valve (i.e., switched to the open state).

[0071] It should be noted that the above description is based on the case where the present invention is applied to a hydraulic excavator, but the invention is not limited thereto. That is, the present invention may also be applied to other construction machines (such as a wheel loader, etc.).

[0072] Description of Reference Numerals

[0073] 4 Travel motors

[0074] 8 Boom Cylinder

[0075] 9 stick cylinder

[0076] 10 Bucket Cylinder

[0077] 14 Working oil tank

[0078] 16 Hydraulic pump

[0079] 17. Control valve

[0080] 23. 23A Additive tank

[0081] 24, 24A Additive supply pipeline

[0082] 25, 25A on-off valve

[0083] 27 Oxidation sensor

[0084] 28 Controllers

Claims

1. An engineering machine, comprising: A working oil tank storing working oil; a hydraulic pump pressurizing the working oil in the working oil tank; a hydraulic actuator; and a control valve for controlling the supply of working oil from the hydraulic pump to the hydraulic actuator and the discharge of working oil from the hydraulic actuator to the working oil tank, characterized in that it includes: An additive tank for storing additives; an additive supply line that supplies additive from the additive tank to the working oil tank; an on-off valve disposed in the additive supply line and switchable between a closed state and an open state, wherein the supply of the additive from the additive tank to the working oil tank is blocked in the closed state, and the supply of the additive from the additive tank to the working oil tank is performed in the open state; an oxidation degree sensor for detecting the degree to which oxidation of the working oil has progressed; and Controller, The controller calculates a rate of change of the degree of oxidation of the working oil based on a detection result of the oxidation degree sensor, and when the rate of change of the degree of oxidation of the working oil is greater than a predetermined value, performs control of notifying that the on-off valve is switched to the open state or controls that switches the on-off valve to the open state, When the rate of change of the degree of oxidation of the working oil is lower than a specified value and the mechanical operating time since the working oil was replaced or the mechanical operating time since the on-off valve was switched from the open state to the closed state is greater than a specified value, control is performed to notify that the on-off valve is switched to the open state or control is performed to switch the on-off valve to the open state.

2. The construction machinery according to claim 1, characterized in that: The additive is an antioxidant.

3. The construction machine according to claim 1, characterized in that: The additives are antioxidants and extreme pressure agents.

4. The construction machinery according to claim 2, characterized in that: The antioxidant is diphenylamine or / and 2,6-di-tert-butyl-p-cresol, and the added concentration thereof is in the range of 0.1 to 0.3 wt %.

5. The construction machine according to claim 3, characterized in that: The antioxidant is diphenylamine or / and 2,6-di-tert-butyl-p-cresol, and the added concentration thereof is in the range of 0.1 to 0.3 wt %.

6. The construction machine according to claim 3, characterized in that: The extreme pressure agent is tricresyl phosphate, and its added concentration is in the range of 0.5-1.5wt%.

7. The construction machine according to claim 3, characterized in that: The extreme pressure agent is dioleyl hydrogen phosphite, and its added concentration is in the range of 0.1 to 1.0 wt%.

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