JP2020133320A - Construction machine - Google Patents

Abstract

To accurately detect properties of hydraulic oil by an oil sensor, and improve durability and reliability.SOLUTION: A construction machine is provided with a hydraulic motor 2A of a lower travel body 2 as a hydraulic actuator, a hydraulic motor 3A of a swing device 3, and a main return conduit 17 which returns hydraulic oil discharged from a boom cylinder 5D, an arm cylinder 5E and a bucket cylinder 5F of a front device 5 into a hydraulic oil tank 14 through an oil cooler 13. On a downstream return conduit part 17B of the main return conduit 17, an oil sensor 18 that detects properties of the hydraulic oil is provided.SELECTED DRAWING: Figure 7

Description

The present invention relates to, for example, a construction machine such as a hydraulic excavator having a configuration in which hydraulic oil is circulated between a hydraulic oil tank and a hydraulic actuator.

In general, a hydraulic excavator as a construction machine has a self-propelled lower traveling body, an upper rotating body provided on the lower traveling body so as to be swivel via a swivel device, and an operation of elevation on the front part of the upper swivel body. It is composed of a front device provided so as to be capable of. Further, various hydraulic actuators are provided on the lower traveling body, the turning device, and the front device.

The upper swing body includes a hydraulic pump driven by a prime mover such as an engine to supply hydraulic oil to a hydraulic actuator, an oil cooler for cooling the hydraulic oil, and a hydraulic oil tank for storing the hydraulic oil. Further, the upper swing body is discharged from the hydraulic actuator, the supply pipeline connecting the hydraulic oil tank, the hydraulic pump, and each hydraulic actuator in order to supply the hydraulic oil in the hydraulic oil tank to each hydraulic actuator. There is a return pipeline that returns the hydraulic oil to the hydraulic oil tank via the oil cooler.

Further, in order to grasp the operating state of the hydraulic excavator, the hydraulic excavator is provided with an operating sensor that detects operating data including engine exhaust temperature, exhaust pressure, lubricating oil temperature, hydraulic oil temperature, pressure, and the like. (See, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2000-259729

Here, it is important to grasp the properties of the hydraulic oil in the hydraulic excavator, and if the hydraulic oil deteriorates or foreign matter is mixed in the hydraulic oil, the performance of each hydraulic actuator and hydraulic pump deteriorates. There is a risk of In this case, in order to accurately grasp the properties of the hydraulic oil, the point of detecting the properties of the hydraulic oil is important. However, in the invention of Patent Document 1, since the detection point of the hydraulic oil by the operation sensor is not determined, there is a possibility that the properties of the hydraulic oil cannot be accurately detected.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a construction machine capable of accurately detecting the properties of hydraulic oil by an oil sensor and improving durability and reliability. To do.

The present invention includes a main body provided with a front device, a hydraulic actuator provided on the main body and the front device, a hydraulic pump for supplying hydraulic oil to the hydraulic actuator, and an oil provided on the main body to cool the hydraulic oil. Between the cooler, the hydraulic oil tank provided in the main body and storing the hydraulic oil, and the hydraulic oil tank, the hydraulic pump, and the hydraulic actuator in order to supply the hydraulic oil in the hydraulic oil tank to the hydraulic actuator. In a construction machine configured to include a supply pipeline connected to the hydraulic actuator and a return pipeline for returning the hydraulic oil discharged from the hydraulic actuator to the hydraulic oil tank via the oil cooler, the return pipeline An oil sensor for detecting the properties of the hydraulic oil is provided in the downstream return pipeline portion connected between the oil cooler and the hydraulic oil tank.

According to the present invention, the properties of hydraulic oil can be accurately detected by the oil sensor, and durability and reliability can be improved.

It is a front view which shows the hydraulic excavator which concerns on 1st Embodiment of this invention. It is a top view which shows the upper swing body enlarged together with a part of a front device. It is a perspective view which shows the posterior part of the upper swing body enlarged. It is an enlarged perspective view of the main part which shows the state which exposed the oil sensor and the oil sampling port provided in the return pipe from the maintenance opening of the exterior cover. It is a perspective view which shows an oil cooler, a hydraulic oil tank, a control valve, a supply line, a return line, an oil sensor, and an oil sampling port. It is a block diagram which shows typically the flow path of hydraulic oil. It is a perspective view which looked at the return line by 2nd Embodiment of this invention from the same position as FIG. 5 together with an oil cooler, a hydraulic oil tank, a control valve, a supply line, an oil sensor, and an oil sampling port. ..

Hereinafter, a crawler type hydraulic excavator will be taken as an example as a typical example of the construction machine according to the embodiment of the present invention, and will be described in detail with reference to the accompanying drawings.

1 to 6 show the first embodiment of the present invention. The hydraulic excavator 1 includes a crawler-type lower traveling body 2 capable of self-propelling in the front and rear directions, an upper swivel body 4 mounted on the lower traveling body 2 so as to be swivelable via a swivel device 3, and an upper swivel body. It is composed of a front device 5 which is provided in the front part in the front and rear directions of the 4 so as to be able to move up and down and excavates earth and sand. The lower traveling body 2 and the upper rotating body 4 constitute a main body. Further, the lower traveling body 2 has a traveling hydraulic motor 2A (shown in FIG. 6), and the turning device 3 has a turning hydraulic motor 3A (shown in FIG. 6). These hydraulic motors 2A and 3A constitute a hydraulic actuator.

The front device 5 is provided at the front portion of the swivel frame 6, which will be described later. The front device 5 is rotatably attached to a boom 5A in which the foot portion on the base end side is attached to the front portion of each of the vertical plates 6B and 6C of the swivel frame 6 so as to be able to move up and down, and to the tip portion of the boom 5A. It is composed of an arm 5B, a bucket 5C rotatably attached to the tip of the arm 5B, and a boom cylinder 5D, an arm cylinder 5E, and a bucket cylinder 5F as hydraulic actuators for driving these. The front device 5 can be replaced with the bucket 5C, and other working tools such as a grapple, a cutter, and a breaker (none of which are shown) can be attached. When other work tools are attached, hydraulic actuators may be added depending on the work tools to be attached.

As shown in FIG. 2, the swivel frame 6 constituting the upper swivel body 4 is erected at the bottom plate 6A and the bottom plate 6A at left and right directions toward the center, and is placed on the bottom plate 6A in the front and rear directions. It is provided with an extended left vertical plate 6B and a right vertical plate 6C. The foot portions of the boom 5A of the front device 5 are attached to the left and right vertical plates 6B and 6C in front of the vertical plates 6B and 6C so that they can move up and down.

The counterweight 7 is attached to the rear portion of the swivel frame 6 in order to balance the weight with the front device 5. The cab 8 is provided on the left front portion of the swivel frame 6, and is provided with a driver's seat, an operation lever for traveling, an operation lever for work, and the like (none of which are shown).

The engine 9 is located in front of the counterweight 7 and is mounted on the turning frame 6 in a horizontal position extending in the left and right directions (shown by a dotted line in FIG. 2). The engine 9 is supported on the swivel frame 6 in a vibration-proof state. On the left side of the engine 9, a cooling fan 9A for supplying cooling air to the heat exchange device 12 described later is provided. On the other hand, a hydraulic pump 11 is provided on the right side of the engine 9. Further, the engine 9 is provided with an exhaust gas treatment device 10 connected to treat the exhaust gas discharged from the engine 9.

The hydraulic pump 11 is provided on the right side of the engine 9. The hydraulic pump 11 is driven by the engine 9 to use the hydraulic oil supplied from the hydraulic oil tank 14, which will be described later, as the hydraulic oil, and the hydraulic oil is used as the pressure oil via the control valve 15 to the hydraulic motor 2A of the lower traveling body 2. It is supplied to the cylinders 5D, 5E, 5F, etc. of 3A and the front device 5.

The heat exchange device 12 is located on the left side of the engine 9 and is provided so as to face the cooling fan 9A. The heat exchange device 12 has a rectangular frame body 12A mounted on the swivel frame 6 of the upper swivel body 4 constituting the main body, and the oil cooler 13 (see FIG. 5) and the radiator are contained in the frame body 12A. , Intercooler (none of them are shown), etc.

The oil cooler 13 is provided on the frame body 12A alongside the radiator, the intercooler, and the like. The oil cooler 13 cools the hydraulic oil returned to the hydraulic oil tank 14. The oil cooler 13 has an inflow pipe 13A at an upper position in the upper and lower directions and an outflow pipe 13B at a lower position. An upstream return pipe portion 17A of the main return pipe 17, which will be described later, is connected to the inflow pipe 13A. On the other hand, the downstream return pipeline portion 17B is connected to the outflow pipe 13B.

The hydraulic oil tank 14 is located on the front side of the hydraulic pump 11 and is provided on the right side of the swivel frame 6. The hydraulic oil tank 14 is composed of a cylindrical body portion 14A, an upper lid portion 14B that closes the upper side of the body portion 14A, and a lower lid portion 14C that closes the lower side of the body portion 14A. The hydraulic oil tank 14 stores hydraulic oil inside. The hydraulic oil tank 14A is located on the upper side and has a built-in filter 14D (shown by a dotted line in FIG. 6). This filter 14D removes foreign matter such as wear particles when hydraulic oil flows through the hydraulic pump 11, control valve 15, each hydraulic motor 2A, 3A, and each cylinder 5D, 5E, 5F. .. The filter 14D is arranged at the most downstream portion of the hydraulic oil flow path including the supply line 16 and the main return line 17.

The control valve 15 is located, for example, on the front side of the engine 9 and is provided on the swivel frame 6. The control valve 15 supplies pressure oil to various hydraulic actuators such as the hydraulic motor 2A of the lower traveling body 2, the hydraulic motor 3A of the swivel device 3, the boom cylinder 5D of the front device 5, the arm cylinder 5E, and the bucket cylinder 5F. It is configured as an assembly of a plurality of directional control valves that control exhaust.

Here, the control valve 15 bypasses the inflow port where the pressure oil supplied from the hydraulic pump 11 flows in, the main outflow port where the hydraulic oil flows out toward the oil cooler 13, and the oil cooler 13 to the hydraulic oil tank 14. It is provided with a sub-outflow port through which hydraulic oil flows toward, and a supply / discharge port through which pressure oil flows out and flows between the hydraulic motors 2A, 3A, cylinders 5D, 5E, 5F, and the like.

The supply pipeline 16 supplies the hydraulic oil in the hydraulic oil tank 14 to the hydraulic motors 2A, 3A, cylinders 5D, 5E, 5F, etc. as hydraulic actuators, so that the hydraulic oil tank 14, the hydraulic pump 11, and the hydraulic motor 2A , 3A, cylinders 5D, 5E, 5F are connected to each other. The supply line 16 includes an upstream supply line 16A connecting the hydraulic oil tank 14 and the hydraulic pump 11, a downstream supply line 16B connecting the hydraulic pump 11 and the control valve 15, and the control valve 15 and hydraulic pressure. It is composed of a plurality of sets of supply / discharge pipe passage portions 16C, which are provided by connecting the motors 2A and 3A and the cylinders 5D, 5E and 5F to form a set of two.

The supply / discharge pipe passage portion 16C switches between supply and discharge according to the rotation directions of the hydraulic motors 2A and 3A and the expansion / contraction operations of the cylinders 5D, 5E and 5F. That is, each supply / discharge line portion 16C constitutes both a part of the downstream supply line part 16B of the supply line 16 and a part of the upstream return line part 17A of the main return line 17 described later. ing.

The main return line 17 constitutes a return line for returning the hydraulic oil discharged from the hydraulic motors 2A and 3A and the cylinders 5D, 5E and 5F into the hydraulic oil tank 14 via the oil cooler 13. The main return line 17 is composed of an upstream return line 17A connecting the control valve 15 and the oil cooler 13 and a downstream return line 17B connecting the oil cooler 13 and the hydraulic oil tank 14. It is configured. As described above, a part of the upstream return line section 17A includes each supply / discharge line section 16C of the supply line 16.

In the upstream return pipeline portion 17A, the upstream side in the hydraulic oil flow direction is connected to the main outflow port of the control valve 15. On the other hand, the downstream side is connected to the inflow pipe 13A of the oil cooler 13.

The upstream side of the downstream return pipeline portion 17B in the flow direction of the hydraulic oil is connected to the outflow pipe 13B of the oil cooler 13. On the other hand, the downstream side is connected to the filter 14D by the hydraulic oil tank 14. Here, the downstream return pipeline portion 17B is divided into an upstream portion 17B1 on the oil cooler 13 side, a downstream portion 17B2 on the hydraulic oil tank 14 side, and an intermediate portion 17B3 between the upstream portion 17B1 and the downstream portion 17B2. be able to. In this case, since the upstream portion 17B1 is connected to the outflow pipe 13B located below the oil cooler 13, it is arranged at a low position in the exterior cover 21 described later. Further, the position near the oil cooler 13 in which the upstream portion 17B1 is arranged is a position that can be reached from the outside on the left side of the upper swivel body 4 by opening the left opening / closing cover portion 22 of the exterior cover 21 described later. ..

Since the downstream portion 17B2 is connected to the filter 14D located on the upper side of the hydraulic oil tank 14, it is arranged at a high position. The high position in the exterior cover 21 on which the downstream portion 17B2 is arranged faces the maintenance opening 24A provided in the upper surface cover portion 24 of the exterior cover 21. That is, the downstream portion 17B2 is in a position where an operator who gets on the upper surface cover portion 24 can easily reach the opening 24A for maintenance by inserting his / her hand.

Further, the downstream portion 17B2 is provided with a sensor connection port 17C and a port connection port 17D. The sensor connection port 17C and the port connection port 17D are, for example, formed of a tubular body having a female screw formed on the inner peripheral side, and are located on the outer peripheral side of the downstream portion 17B2 so as to communicate with the oil passage in the main return pipe 17. It is stuck. An oil sensor 18 described later is connected to the sensor connection port 17C, and an oil sampling port 19 described later is connected to the port connection port 17D.

The oil sensor 18 is provided in the downstream return line portion 17B of the main return line 17 that connects the oil cooler 13 and the hydraulic oil tank 14. The oil sensor 18 detects the properties of the hydraulic oil. For example, it detects the viscosity, concentration, non-conductivity, temperature, etc. of the hydraulic oil and outputs it to a controller (not shown). The oil sensor 18 is attached to the sensor connection port 17C of the downstream return pipeline portion 17B. Further, the oil sensor 18 is arranged so as to project forward from the downstream portion 17B2, whereby inspection work and replacement work can be easily performed through the opening 24A for maintenance.

The oil sampling port 19 is provided in the downstream return pipeline portion 17B together with the oil sensor 18. The oil sampling port 19 constitutes an extraction port for extracting the actual hydraulic oil in order to investigate the properties of the hydraulic oil in more detail. The oil sampling port 19 has a built-in check valve, for example, and the hydraulic oil can be taken out by forcibly opening the check valve. The extracted hydraulic oil is sent to an inspection agency for inspection. Further, the oil sampling port 19 is provided at the same position as the oil sensor 18 in the flow direction of the hydraulic oil. As a result, the hydraulic oil detected by the oil sensor 18 can be extracted as an inspection target. Further, the oil sampling port 19 is attached so as to project downward from the port connection port 17D of the downstream return pipeline portion 17B.

In this way, in the configuration in which the oil sampling port 19 is provided together with the oil sensor 18, it is possible to compare the detection result of the hydraulic oil by the oil sensor 18 with the inspection result of the actual hydraulic oil extracted from the oil sampling port 19. it can. As a result, it is possible to find defects in the equipment related to the property detection of the hydraulic oil including the oil sensor 18 as the difference between the results.

Here, the downstream portion 17B2 of the downstream return pipeline portion 17B to which the oil sensor 18 and the oil sampling port 19 are attached is the most downstream portion of the hydraulic oil flow path including the supply pipeline 16 and the main return pipeline 17. It is in the vicinity of the filter 14D. Therefore, the hydraulic oil that has passed through equipment such as the hydraulic pump 11, the control valve 15, the hydraulic motors 2A and 3A, and the cylinders 5D, 5E and 5F flows through the downstream portion 17B2. From this, when foreign matter such as wear particles is generated in each device, the amount of foreign matter mixed in the hydraulic oil is maximized in the downstream portion 17B2. As a result, the oil sensor 18 can detect the properties of the hydraulic oil having the worst properties at present, and the oil sampling port 19 can extract the properties of the hydraulic oil having the worst properties at present.

The sub return line 20 connects the control valve 15 and the hydraulic oil tank 14. In the sub return line 20, the upstream side in the hydraulic oil flow direction is connected to the sub outflow port of the control valve 15, and the downstream side is connected to the filter 14D of the hydraulic oil tank 14. The sub return line 20 returns the hydraulic oil directly from the control valve 15 to the hydraulic oil tank 14.

The exterior cover 21 is located between the cab 8 and the counterweight 7 and is provided on the swivel frame 6. The exterior cover 21 covers the engine 9, the hydraulic pump 11, the heat exchange device 12 including the oil cooler 13, the supply line 16 and the return lines 17, 20. The exterior cover 21 includes a left opening / closing cover portion 22, a right opening / closing cover portion 23, and an upper surface cover portion 24.

The left opening / closing cover portion 22 is provided between the cab 8 and the counterweight 7 so as to cover the left side of the heat exchange device 12. Further, the left opening / closing cover portion 22 is provided, for example, so as to be rotatable (openable / closable) in the horizontal direction, and when the door is opened, maintenance of the heat exchange device 12 and the like can be performed.

The right opening / closing cover portion 23 is provided between the hydraulic oil tank 14 and the counterweight 7 so as to cover the right side of the hydraulic pump 11. Further, the right opening / closing cover portion 23 is provided, for example, so as to be rotatable (openable / closable) in the horizontal direction, and when the door is opened, maintenance of the hydraulic pump 11 and the like can be performed.

The upper surface cover portion 24 is provided between the cab 8 and the counter weight 7 so as to cover the engine 9, the hydraulic pump 11, the heat exchange device 12, the supply pipeline 16 and the return pipelines 17 and 20 from above. The upper surface cover portion 24 is provided with an opening 24A (see FIG. 4) for maintenance extending in the left and right directions on the left side of the hydraulic oil tank 14 on the front side of the engine cover portion 24C (engine 9). The opening 24A opens at an upper position facing the oil sensor 18 and the oil sampling port 19. Further, the upper surface cover portion 24 is provided with a closing plate 24B that can cover the opening 24A so as to be removable (openable and closable).

A maintenance opening (not shown) is provided on the rear side of the upper surface cover portion 24 by opening the upper side of the engine 9, the hydraulic pump 11, and the heat exchange device 12. Further, the upper surface cover portion 24 is provided with an engine cover portion 24C that covers the maintenance opening so as to be openable and closable.

The fuel tank 25 is located on the front side of the hydraulic oil tank 14 and is provided on the swivel frame 6. The fuel tank 25 stores fuel to be supplied to the engine 9, and is formed as a rectangular parallelepiped container.

The hydraulic excavator 1 according to the present embodiment has the above-described configuration, and its operation will be described next.

First, the operator gets on the cab 8 and operates the engine 9. Then, the operator can drive the hydraulic excavator 1 by operating the traveling operation lever (not shown) arranged in the cab 8, and operate the operating operating lever (not shown). By doing so, the swivel device 3 and the front device 5 can be operated to perform the earth and sand excavation work.

Here, when the engine 9 is operated, the hydraulic oil in the hydraulic oil tank 14 is used as pressure oil by the hydraulic pump 11 to the control valve 15 through the upstream supply line 16A and the downstream supply line 16B of the supply line 16. Will be supplied. In this state, when the operator in the cab 8 operates each operation lever, the pressure oil is supplied to the hydraulic motor 2A of the lower traveling body 2, the hydraulic motor 3A of the swivel device 3, and the front device 5 via the supply / discharge pipe passage portions 16C. Is supplied and discharged between the boom cylinder 5D, the arm cylinder 5E, and the bucket cylinder 5F. As a result, each hydraulic actuator including the hydraulic motors 2A and 3A and the cylinders 5D, 5E and 5F can be operated.

On the other hand, the pressure oil discharged from the hydraulic motors 2A and 3A and the cylinders 5D, 5E and 5F is returned to the control valve 15 through the supply and discharge pipe lines 16C. The pressure oil returned to the control valve 15 is supplied to the oil cooler 13 through the upstream return line portion 17A of the main return line 17. The oil cooler 13 cools the supplied pressure oil. Then, the pressure oil cooled by the oil cooler 13 is returned to the hydraulic oil tank 14 through the downstream return pipeline portion 17B. At this time, in the hydraulic oil tank 14, foreign matter such as wear particles mixed in the pressure oil is removed by the filter 14D, and the pressure oil (hydraulic oil) is cleaned. When the temperature of the pressure oil (hydraulic oil) is low and it is not necessary to cool the pressure oil, the pressure oil is returned to the hydraulic oil tank 14 through the sub return pipe 20.

In this way, when the pressure oil is circulated in the supply pipes 16 and the return pipes 17 and 20, the hydraulic pump 11, the control valve 15, the hydraulic motors 2A and 3A, and the cylinders 5D, 5E and 5F have worn particles and the like. Foreign matter may be generated and the hydraulic oil may be mixed with foreign matter. When the amount of foreign matter mixed in the hydraulic oil increases, damage or deterioration of the hydraulic pump 11, control valve 15, hydraulic motors 2A, 3A, cylinders 5D, 5E, 5F, etc. is suspected. Therefore, the hydraulic excavator 1 inspects the properties of the hydraulic oil.

The property inspection of the hydraulic oil in the hydraulic excavator 1 will be described. First, the oil sensor 18 detects the viscosity, concentration, non-conductivity, temperature, etc. of the hydraulic oil flowing through the main return pipe 17, and outputs the oil sensor 18 to the controller. As a result, the controller inspects the properties of the hydraulic oil based on the detection result, and informs the replacement time and the like.

Further, in the sampling operation using the oil sampling port 19, the operator gets on the upper surface cover portion 24 of the exterior cover 21 and removes the closing plate 24B. As a result, the oil sampling port 19 is exposed through the opening 24A. Therefore, the operator inserts a hand through the opening 24A to extract the hydraulic oil flowing through the main return pipe 17 from the oil sampling port 19. can do. The extracted hydraulic oil is sent to an inspection agency for detailed inspection. As a result, the properties of the hydraulic oil, the replacement time, etc. are communicated based on the inspection results.

Thus, in the present embodiment, the downstream return pipe portion 17B of the main return pipe 17 is provided with an oil sensor 18 for detecting the properties of the hydraulic oil. Here, the downstream portion 17B2 of the downstream return pipeline portion 17B to which the oil sensor 18 is attached is the most downstream portion of the hydraulic oil flow path including the supply pipeline 16 and the main return pipeline 17. Therefore, by detecting the properties of the hydraulic oil with the oil sensor 18 provided in the downstream portion 17B2 of the downstream return pipeline portion 17B, the worst properties of the hydraulic oil at present can be detected.

As a result, the oil sensor 18 can accurately detect the properties of the hydraulic oil, and can take measures based on the detection result. As a result, not only the hydraulic oil but also the durability and reliability of the hydraulic pump 11, the control valve 15, the hydraulic motors 2A and 3A, the cylinders 5D, 5E, 5F and the like can be improved.

An oil sampling port 19 for taking out a sample of hydraulic oil is provided in the downstream portion 17B2 of the downstream return pipeline portion 17B of the main return pipeline 17. The inspection result of the hydraulic oil extracted from the oil sampling port 19 can grasp the properties of the hydraulic oil with high accuracy. On the other hand, in the configuration in which the oil sensor 18 and the oil sampling port 19 are provided at the same position in the flow direction of the hydraulic oil, the detection result of the hydraulic oil by the oil sensor 18 and the inspection of the actual hydraulic oil extracted from the oil sampling port 19 are performed. The results can be compared. That is, it is possible to find a defect in the equipment related to the property detection of the hydraulic oil including the oil sensor 18 as a difference between the two results, and promptly issue an instruction for repair, replacement, etc. of the oil sensor 18. ..

The upper swivel body 4 is provided with an exterior cover 21 that covers the hydraulic pump 11, the oil cooler 13, the supply pipe line 16, and the return pipe lines 17, 20. On this, the upper surface cover portion 24 of the exterior cover 21 is provided with an opening 24A for maintenance at a position facing the oil sensor 18 and the oil sampling port 19. As a result, the operator riding on the upper surface cover portion 24 of the exterior cover 21 can reach from the opening 24A toward the oil sensor 18 and the oil sampling port 19. As a result, the oil sensor 18 can be easily repaired, replaced, and sampled by the oil sampling port 19.

Next, FIG. 7 shows a second embodiment of the present invention. The feature of this embodiment is that the oil sensor and the oil sampling port are provided near the oil cooler side of the downstream return pipeline portion of the return pipeline. In this embodiment, the same components as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 7, the main return pipe 31 according to the second embodiment constitutes a return pipe in substantially the same manner as the main return pipe 17 according to the first embodiment, and the upstream return pipe portion 31A and the downstream It includes a return pipeline portion 31B, a sensor connection port 31C, and a port connection port 31D. Further, the downstream return pipeline portion 31B can be divided into an upstream portion 31B1, a downstream portion 31B2 and an intermediate portion 31B3.

However, the main return line 31 according to the second embodiment is provided with a sensor connection port 31C and a port connection port 31D at the upstream portion 31B1 of the downstream return line portion 31B, according to the first embodiment. It is different from the main return line 17 by. As a result, the sensor connection port 31C and the port connection port 31D are arranged in the vicinity of the outflow pipe 13B of the oil cooler 13. An oil sensor 18 is attached to the sensor connection port 31C, and an oil sampling port 19 is attached to the port connection port 31D.

Thus, even in the second embodiment configured as described above, the same actions and effects as those in the first embodiment described above can be obtained. In particular, in the second embodiment, the oil sensor 18 and the oil sampling port 19 are arranged in the vicinity of the outflow pipe 13B of the oil cooler 13. Therefore, by opening the left opening / closing cover portion 22 of the exterior cover 21, the oil sensor 18 and the oil sampling port 19 can be reached from the outside on the left side of the upper swing body 4. As a result, the operator can perform the repair work, the replacement work, and the sampling work by the oil sampling port 19 of the oil sensor 18 without climbing on the exterior cover 21.

In the first embodiment, the case where the oil sensor 18 and the oil sampling port 19 are provided in the downstream return pipe portion 17B of the main return pipe 17 will be described as an example. However, the present invention is not limited to this, and a configuration in which only the oil sensor 18 is provided in the downstream return pipeline portion 17B may be provided. This configuration can be similarly applied to the second embodiment.

Further, in each embodiment, the hydraulic excavator 1 provided with the crawler type lower traveling body 2 has been described as an example of the construction machine. However, the present invention is not limited to this, and may be applied to, for example, a hydraulic excavator provided with a wheel-type lower traveling body. Besides that, it can be widely applied to other construction machines such as wheel loaders and hydraulic cranes.

1 Hydraulic excavator (construction machinery)
2 Lower running body (main body)
2A, 3A hydraulic motor (hydraulic actuator)
3 Swivel device 4 Upper swivel body (main body)
5 Front device 5D boom cylinder (hydraulic actuator)
5E arm cylinder (hydraulic actuator)
5F bucket cylinder (hydraulic actuator)
11 Hydraulic pump 13 Oil cooler 14 Hydraulic oil tank 15 Control valve 16 Supply line 17,31 Main return line (return line)
17A, 31A Upstream return line 17B, 31B Downstream return line 18 Oil sensor 19 Oil sampling port 21 Exterior cover 24 Top cover 24A Opening

Claims (3)

The main body with the front device and
Hydraulic actuators provided on the main body and the front device,
A hydraulic pump that supplies hydraulic oil to the hydraulic actuator,
An oil cooler provided on the main body to cool the hydraulic oil,
A hydraulic oil tank provided in the main body and storing hydraulic oil,
A supply pipeline connecting the hydraulic oil tank, the hydraulic pump, and the hydraulic actuator in order to supply the hydraulic oil in the hydraulic oil tank to the hydraulic actuator.
In a construction machine configured to include a return pipe for returning the hydraulic oil discharged from the hydraulic actuator to the hydraulic oil tank via the oil cooler.
A construction machine characterized in that an oil sensor for detecting the properties of hydraulic oil is provided in a downstream return pipeline portion of the return pipeline connecting between the oil cooler and the hydraulic oil tank. The construction machine according to claim 1, wherein the downstream return pipeline portion is provided with an oil sampling port for taking out a sample of hydraulic oil. The main body is provided with an exterior cover that covers the hydraulic pump, the oil cooler, the supply line, and the return line.
The construction machine according to claim 2, wherein the exterior cover is provided with an opening for maintenance at a position facing the oil sensor and the oil sampling port.

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