Construction machine

Abstract

A vehicle body of a hydraulic excavator (1) comprises: a slewing frame (5) on the front side of which a work device (4) is attached; a hydraulic oil tank (10) mounted on the slewing frame (5); and an exterior cover (13) provided to the slewing frame (5) and forming a tank chamber (20) accommodating the hydraulic oil tank (10). The exterior cover (13) has an opening / closing cover (22) for openably / closably covering an opening (21) of the tank chamber (20). A pressure control valve (25) that has a solenoid part (25B) and controls the flow of hydraulic oil supplied to a hydraulic actuator is provided inside the tank chamber (20), and the solenoid part (25B) is disposed between an upper end and a lower end of the opening (21) in the vertical direction.

Description

Construction machinery

[0001] The present disclosure relates to construction machinery such as hydraulic excavators.

[0002] A hydraulic excavator, which is representative of construction machinery, includes a self-propelled lower traveling body, an upper revolving body that is rotatably provided on the lower traveling body, and a working device provided on the front side of the upper revolving body. An hydraulic pump driven by a prime mover is mounted on the upper revolving body. The hydraulic oil (pressure oil) discharged from the hydraulic pump is supplied to various hydraulic actuators mounted on the hydraulic excavator. Thereby, the hydraulic excavator travels to the work site and performs excavation work and the like using the working device while revolving the upper revolving body.

[0003] The hydraulic excavator is applied to various works by replacing the attachment attached to the tip of the working device. The attachments of the hydraulic excavator are diversified, and the pressure of the hydraulic oil supplied to the hydraulic actuator for driving the working device may need to be adjusted according to the type of attachment. For this reason, a solenoid valve for adjusting the pressure of the hydraulic oil supplied to the hydraulic actuator is provided in the hydraulic circuit for driving the working device. Here, when replacing the piping constituting the hydraulic circuit, it is necessary to perform maintenance such as bleeding air on the solenoid valve provided in the hydraulic circuit. For this reason, it is desirable to secure a large working space around the solenoid valve for maintenance.

[0004] For example, Patent Document 1 discloses a hydraulic excavator including a vehicle body frame having a bottom plate, side plates erected on the bottom plate, and a ceiling plate that can be opened and closed around a hinge, and solenoid valves are attached to the bottom plate and the ceiling plate. In this prior art, by rotating and opening the ceiling plate, a large working space can be formed around the solenoid valve attached to the bottom plate and the solenoid valve attached to the ceiling plate.

[0005] Japanese Patent Application Laid-Open No. 2002-294750

[0006] However, in the hydraulic excavator disclosed in Patent Document 1, when the ceiling panel is opened around the hinge, the solenoid valve attached to the ceiling panel moves to the inside of the vehicle body (towards the pivot point), moving away from the operator performing maintenance on the solenoid valve. As a result, it is difficult for the operator to access the solenoid valve, which is the target of maintenance, and the efficiency of maintenance work is reduced. Furthermore, when opening and closing the ceiling panel around the hinge, heavy objects such as the solenoid valve and hydraulic hoses rotate together with the ceiling panel, further reducing the efficiency of maintenance work on the solenoid valve attached to the ceiling panel.

[0007] The present invention has been made in view of the problems of the prior art described above, and the object of the present invention is to provide a construction machine that can improve the workability when performing maintenance on a control valve.

[0008] The present invention relates to a construction machine comprising a self-propelled vehicle body, a work device provided on the vehicle body, and a hydraulic actuator for operating the work device, wherein the vehicle body comprises a vehicle frame to which the work device is attached to the front, a hydraulic oil tank mounted on the vehicle frame for storing hydraulic oil supplied to the hydraulic actuator, and an exterior cover provided on the vehicle frame for forming a tank chamber that houses the hydraulic oil tank, wherein the tank chamber is provided with an opening that opens to the inside of the tank chamber, and the exterior cover has an opening / closing cover that opens and closes the opening of the tank chamber, wherein the inside of the tank chamber is provided with a maintenance section for discharging the hydraulic oil and a control valve for controlling the flow of the hydraulic oil supplied to the hydraulic actuator, and the maintenance section of the control valve is positioned vertically between the upper end and the lower end of the opening.

[0009] According to the present invention, since the maintenance section of the control valve faces the opening when the opening is open, the maintenance section of the control valve can be easily accessed through the opening, thereby improving the efficiency of maintenance work.

[0010] This is a left side view showing a hydraulic excavator according to an embodiment of the present invention. This is a perspective view of the upper rotating body from the right front with the opening / closing cover open. This is a top view of the tank interior from above with the opening / closing cover removed. This is a right side view of the upper rotating body with the opening / closing cover open, viewed from the direction indicated by arrow IV-IV in Figure 2. This is a left side view of the hydraulic oil tank, fuel tank, pressure control valve, etc., viewed from the left side with the opening / closing cover open. This is a left side view showing the hydraulic oil tank, pressure control valve, etc. This is a perspective view of the upper rotating body from the right front showing the state of performing air bleeding work on the pressure control valve. This is a hydraulic circuit diagram including the boom cylinder, pressure control valve, etc. This is a left side view of the same position as in Figure 5, showing a modified example of the mounting position of the pressure control valve.

[0011] Hereinafter, embodiments of the present invention will be described in detail, using a hydraulic excavator as an example, with reference to Figures 1 to 8. In these embodiments, the direction of travel of the hydraulic excavator will be described as the front-rear direction, and the direction perpendicular to the direction of travel will be described as the left-right direction.

[0012] A hydraulic excavator 1, a representative construction machine, is equipped with a self-propelled lower vehicle 2 and an upper rotating vehicle 3 that is rotatably mounted on the lower vehicle 2. The body of the hydraulic excavator 1 is composed of the lower vehicle 2 and the upper rotating vehicle 3. The lower vehicle 2 has left and right crawlers (tracks) and can travel stably on uneven work sites. A swing-type working device 4 is rotatably mounted on the front of the upper rotating vehicle 3, and excavation work such as soil digging is performed using the working device 4.

[0013] The swing-type work device 4 includes a swing post 4A that is pivotably mounted on the front side of the slewing frame 5 (described later) so as to swing in the left-right direction, a boom 4B that is rotatably attached to the swing post 4A, an arm 4C that is rotatably attached to the tip of the boom 4B, and a bucket 4D as an attachment that is rotatably attached to the tip of the arm 4C. In addition to the bucket 4D, other attachments that can be attached to the tip of the arm 4C include a grapple, breaker, cutter, drum cutter, etc. Furthermore, the work device 4 is equipped with hydraulic actuators such as a swing cylinder 4E (see Figure 2) for swinging the swing post 4A, a boom cylinder 4F for rotating the boom 4B, an arm cylinder 4G for rotating the arm 4C, and a bucket cylinder 4H for rotating the bucket 4D.

[0014] The upper rotating body 3 is mounted on the lower traveling body 2 via a rotating mechanism so as to be rotatable, and performs rotating movements on the lower traveling body 2. The upper rotating body 3 includes a rotating frame 5 (described later), a counterweight 6, a cab 7, an engine 8 as the prime mover, a hydraulic pump 9, a hydraulic oil tank 10, a fuel tank 11, and an exterior cover 13.

[0015] The slewing frame 5, which serves as the vehicle body frame, forms the base of the upper slewing body 3 and is rotatably mounted to the lower traveling body 2. The slewing frame 5 has a center frame (not shown) located in the center in the left-right direction, left and right vertical plates 5A erected on the center frame and extending in the front-rear direction, a left side frame 5B located on the left side of the center frame, and a right side frame 5C located on the right side of the center frame. Cylindrical support cylinders 5D are fixed to the front ends of the left and right vertical plates 5A. The swing post 4A of the work device 4 is supported on the support cylinders 5D so that it can swing from side to side. A counterweight 6 is provided at the rear end of the center frame. The counterweight 6 maintains the weight balance with the work device 4.

[0016] The cab 7 is located on the front left side of the slewing frame 5 and forms the driver's compartment from which the operator enters and exits. Inside the cab 7 are the driver's seat 7A where the operator sits, a travel lever and pedal device (not shown) operated by the operator, and an operating lever device 31 (see Figure 8), which will be described later. On the rear side of the slewing frame 5 (counterweight 6 side) are the engine 8, a hydraulic pump 9 driven by the engine 8, and a heat exchanger (not shown) for cooling the engine coolant.

[0017] On the right front side of the slewing frame 5, a hydraulic oil tank 10 and a fuel tank 11 are located, serving as oil storage tanks. As shown in Figures 3 and 6, the hydraulic oil tank 10 is formed as a box-shaped body having an upper surface 10A, a lower surface 10B, a front surface 10C, a rear surface 10D, a left side surface 10E, a right side surface 10F, and a left front inclined surface 10G. The hydraulic oil tank 10 stores the hydraulic oil supplied to the hydraulic actuators (boom cylinder 4F, etc.) mounted on the hydraulic excavator 1. The upper surface 10A of the hydraulic oil tank 10 is provided with an oil inlet 10H for supplying hydraulic oil and a return pipe 10J for returning hydraulic oil discharged from the hydraulic actuators back to the hydraulic oil tank 10.

[0018] The fuel tank 11 is positioned adjacent to the front of the hydraulic oil tank 10. The fuel tank 11 is a box having an upper surface 11A, a lower surface (not shown), and a peripheral wall surface 11B that surrounds the peripheral edges of the upper surface 11A and the lower surface and connects them. The fuel tank 11 stores the fuel supplied to the engine 8. The height of the upper surface 11A of the fuel tank 11 is lower than the height of the upper surface 10A of the hydraulic oil tank 10. As a result, a vertical step is formed between the upper surface 10A of the hydraulic oil tank 10 and the upper surface 11A of the fuel tank 11.

[0019] The partition plate 12 is positioned behind the hydraulic oil tank 10 and extends horizontally through the middle section of the upper slewing body 3 in the front-rear direction. The partition plate 12 is a rectangular flat plate extending horizontally and extends from the right side of the cab 7 to the right front side cover 17, which will be described later. The partition plate 12 separates the heat exchanger (not shown) mounted on the rear of the slewing frame 5 from the hydraulic oil tank 10.

[0020] The exterior cover 13 is located in front of the counterweight 6 and is mounted on the slewing frame 5. The exterior cover 13 is attached to a support member (not shown) positioned on the slewing frame 5. The exterior cover 13 covers the mounted equipment on the slewing frame 5, such as the engine 8, hydraulic pump 9, heat exchanger (not shown), hydraulic oil tank 10, and fuel tank 11. As shown in Figures 1 and 2, the exterior cover 13 includes a left side cover 14, a rear top cover 15, a right rear side cover 16, a right front side cover 17, a right front cover 18, a right front top cover 19, and an opening / closing cover 22.

[0021] The left side cover 14 rises upward from the left side frame 5B and is positioned between the left end of the counterweight 6 and the cab 7. The left side cover 14 covers the engine 8 and hydraulic pump 9, etc. from the left side (see Figure 1). The rear top cover 15 is positioned in front of the counterweight 6 and extends horizontally toward the rear of the cab 7. The rear top cover 15 covers the engine 8, hydraulic pump 9, heat exchanger (not shown), etc. from above. The right rear side cover 16 rises upward from the right side frame 5C and extends from the right end of the counterweight 6 to the right end of the partition plate 12. The right rear side cover 16 covers the heat exchanger, etc., located behind the partition plate 12, from the right side.

[0022] The right front side cover 17 rises upward from the right side frame 5C and extends from the front end of the right rear side cover 16 to the front end of the right side frame 5C. The right front side cover 17 has a side cover portion 17A that extends in the front-rear direction and a front cover portion 17B that bends to the left from the front end of the side cover portion 17A. The upper edge of the side cover portion 17A is inclined diagonally downward from the rear end toward the front cover portion 17B. The side cover portion 17A of the right front side cover 17 covers the hydraulic oil tank 10, fuel tank 11, etc., which are located in front of the partition plate 12, from the right side. The front cover portion 17B covers the hydraulic oil tank 10, fuel tank 11, etc., from the front.

[0023] The right front cover 18 is positioned at the corner where the side cover portion 17A and the front cover portion 17B of the right front side cover 17 intersect, and extends from the front cover portion 17B to partway along the side cover portion 17A. Together with the front cover portion 17B of the right front side cover 17, the right front cover 18 covers the hydraulic oil tank 10, fuel tank 11, etc. from the front.

[0024] The right front upper cover 19 is adjacent to the left side of the right front cover 18 and is positioned between the front cover portion 17B of the right front side cover 17 and the partition plate 12. The right front upper cover 19 constitutes the front upper cover portion that covers the tank chamber 20, which will be described later, from the front and above. The right front upper cover 19 curves in an arc shape from its rear end, which is located on the partition plate 12 side, toward the front cover portion 17B and slopes diagonally downward. The right front upper cover 19 covers the fuel tank 11, etc., from the front and above.

[0025] The tank compartment 20 is formed inside the exterior cover 13 and is located on the right front side of the upper rotating body 3. Specifically, the tank compartment 20 is formed as a space enclosed by a partition plate 12, a right front side cover 17, a right front cover 18, a right front top cover 19, and an opening / closing cover 22. The left side of the tank compartment 20 is covered by a cover (not shown) located adjacent to the right side of the cab 7. The bottom of the tank compartment 20 is covered by the bottom plate (not shown) of the rotating frame 5. The tank compartment 20 houses the hydraulic oil tank 10, a fuel tank 11, a pressure control valve 25 (described later), and the like.

[0026] The opening 21 is formed as a rectangular opening surrounded by the front edge 15A of the rear upper cover 15, the upper edge 17C of the side cover portion 17A constituting the right front side cover 17, the upper edge 18A of the right front cover 18, and the right side edge 19A of the right front upper cover 19. The front edge 15A of the rear upper cover 15 constitutes the upper end of the opening 21. The upper edge 18A of the right front cover 18 constitutes the lower end of the opening 21. The opening 21 is used to open the tank chamber 20 to the outside of the upper slewing body 3 when performing maintenance on the hydraulic oil tank 10, fuel tank 11, pressure control valve 25, etc., housed in the tank chamber 20.

[0027] The opening / closing cover 22 constitutes a part of the outer cover 13 and covers the opening 21 so that it can be opened and closed. As shown in Figures 2 and 5, the opening / closing cover 22 extends in the front-rear direction while curving in an arc along the right front upper cover 19. The opening / closing cover 22 has a rear edge 22A, a front edge 22B, a left edge 22C, and a right edge 22D. The rear edge 22A of the opening / closing cover 22 corresponds to the front edge 15A of the rear upper cover 15. The front edge 22B corresponds to the upper edge 18A of the right front cover 18. The left edge 22C corresponds to the right edge 19A of the right front upper cover 19. The right edge 22D corresponds to the upper edge 17C of the right front side cover 17 (side cover portion 17A). The rear side (rear edge 22A side) of the opening / closing cover 22 is supported by the partition plate 12 via a hinge mechanism 23. As a result, the front side (front edge 22B side) of the opening / closing cover 22 rotates vertically or in the front-back direction around the hinge mechanism 23, opening and closing the opening 21.

[0028] Therefore, when performing maintenance on the hydraulic oil tank 10, fuel tank 11, pressure control valve 25, etc., housed in the tank chamber 20, the front of the opening / closing cover 22 is lifted upward to open the opening 21 (see Figure 2). In this state, the worker can access the inside of the tank chamber 20 through the opening 21 and smoothly perform tasks such as air bleeding from the pressure control valve 25.

[0029] A bracket 24 for mounting a pressure control valve 25 is attached to the upper side of the hydraulic fluid tank 10. The bracket 24 is formed from a plate body with a bent portion 24A in the middle in the front-rear direction. The bracket 24 is fixed with bolts to screw seats protruding from the left side surface 10E and the left front inclined surface 10G of the hydraulic fluid tank 10. In this way, the bracket 24 has great strength due to the bent portion 24A and is positioned adjacent to the left side surface 10E and the left front inclined surface 10G of the hydraulic fluid tank 10.

[0030] Next, the pressure control valve 25 used in this embodiment will be described with reference to Figures 5 to 7.

[0031] The pressure control valve 25, acting as a control valve, is mounted on a bracket 24 and positioned in the tank chamber 20 adjacent to the hydraulic oil tank 10. The pressure control valve 25 adjusts the pressure of the hydraulic oil supplied to the hydraulic actuator, such as the boom cylinder 4F, mounted on the hydraulic excavator 1. The pressure control valve 25 is configured as an electromagnetic proportional relief valve, comprising a main body 25A that is rectangular in shape and fixed to the bracket 24 using bolts, etc., and a cylindrical solenoid part 25B that protrudes diagonally downward from the main body.

[0032] The solenoid section 25B of the pressure control valve 25 constitutes the maintenance section that is subject to the air bleeding operation (maintenance) described later. The solenoid section 25B is fixed in a position that is inclined downward from the main body section 25A and outward (to the right) from the vehicle body, and is inclined at an angle θ1 with respect to the vertical (see Figure 5). The lower end (protruding end) of the solenoid section 25B is positioned lower than the upper surface 10A of the hydraulic oil tank 10. This allows the air bleeding operation for the solenoid section 25B to be performed at a position lower and away from the outer cover 13.

[0033] The protruding end of the solenoid section 25B, which serves as a maintenance section, has an outlet (not shown) that allows the hydraulic fluid filled inside the solenoid section 25B to be discharged. This outlet is sealed by a sealing plug 25C. When the hydraulic piping (e.g., hydraulic hose) that constitutes the hydraulic circuit including the pressure control valve 25 is replaced, air may be mixed into the hydraulic fluid filled inside the solenoid section 25B. In this case, an air bleeding operation is performed to discharge the mixed air to the outside by circulating the hydraulic fluid inside the solenoid section 25B with the sealing plug 25C removed.

[0034] Here, as shown in Figure 2, the solenoid section 25B is positioned vertically between the upper end (front edge 15A of the rear upper cover 15) and the lower end (upper edge 18A of the right front cover 18) of the opening 21. Therefore, when the opening / closing cover 22 opens the opening 21 of the outer cover 13, the pressure control valve 25 maintains a posture in which the solenoid section 25B faces the opened opening 21. This allows the worker performing the air bleeding operation to easily access the solenoid section 25B to be maintained through the opening 21. Furthermore, as shown in Figures 2 and 3, when the opening / closing cover 22 opens the opening 21, the solenoid section 25B is positioned so that it is covered from above by the right front upper cover 19. This ensures that even if hydraulic fluid is scattered from the protruding end of the solenoid section 25B after the sealing plug 25C has been removed when performing air bleeding on the pressure control valve 25, this hydraulic fluid can be received by the right front upper cover 19.

[0035] The main body 25A of the pressure control valve 25 is fitted with an inlet fitting 26 as an inlet and an outlet fitting 27 as an outlet. These inlet fitting 26 and outlet fitting 27 are connected to an oil passage formed inside the main body 25A. A valve body for opening and closing the oil passage is also provided inside the main body 25A. By controlling the opening degree of this valve body, the flow rate of hydraulic fluid from the inlet fitting 26 to the outlet fitting 27 is controlled. Here, the inlet fitting 26 and outlet fitting 27 of the pressure control valve 25 are covered from the front and above by a right front upper cover 19 together with the solenoid section 25B. As a result, even if hydraulic fluid is ejected from the inlet fitting 26 or outlet fitting 27, this hydraulic fluid can be received by the right front upper cover 19. As shown in Figure 8, the pressure control valve 25 is connected to a pipeline that supplies hydraulic fluid to, for example, the rod-side oil chamber 4F2 of a boom cylinder 4F. The pressure control valve 25 controls the opening degree of the valve body in accordance with the signal (current) supplied to the solenoid unit 25B.

[0036] In the hydraulic circuit shown in Figure 8, the hydraulic pump 9, driven by the engine 8, together with the hydraulic oil tank 10 constitutes a hydraulic power source. The boom cylinder 4F and the hydraulic power source are connected via a main pipeline 28, and a directional control valve 29 is provided in the middle of the main pipeline 28. The main pipeline 28 has a bottom-side main pipeline 28A that connects the directional control valve 29 to the bottom-side oil chamber 4F1 of the boom cylinder 4F, and a rod-side main pipeline 28B that connects the directional control valve 29 to the rod-side oil chamber 4F2 of the boom cylinder 4F.

[0037] The directional control valve 29 has a pair of hydraulic pilot units 29A and 29B. Pilot pressure from the pilot pump 30 is supplied to the hydraulic pilot units 29A and 29B according to the operating direction and amount of the operating lever device 31 located inside the cab 7. When pilot pressure is supplied to hydraulic pilot unit 29A, hydraulic fluid is supplied to the bottom-side oil chamber 4F1 of the boom cylinder 4F, and the boom cylinder 4F extends. When pilot pressure is supplied to hydraulic pilot unit 29B, hydraulic fluid is supplied to the rod-side oil chamber 4F2 of the boom cylinder 4F, and the boom cylinder 4F retracts.

[0038] An additional pipeline 32 is connected to the main pipeline 28B on the rod side. The pressure control valve 25 is located between the main pipeline 28B on the rod side and the hydraulic oil tank 10 and is connected to the additional pipeline 32. That is, the inlet fitting 26 and outlet fitting 27 of the pressure control valve 25 are each connected to the additional pipeline 32. The solenoid section 25B of the pressure control valve 25 is electrically connected to a controller 33 mounted on the upper swivel body 3. The pressure control valve 25 controls the opening degree of the valve body in accordance with the signal supplied from the controller 33 to the solenoid section 25B.

[0039] For example, when no signal is supplied to the solenoid unit 25B, the pressure control valve 25 closes, and the hydraulic fluid flowing through the rod-side main conduit 28B is supplied to the rod-side oil chamber 4F2 of the boom cylinder 4F without relief. On the other hand, when a signal is supplied to the solenoid unit 25B, the pressure control valve 25 opens, and a portion of the hydraulic fluid flowing through the rod-side main conduit 28B is relieved to the hydraulic fluid tank 10. At this time, the valve opening of the pressure control valve 25 is controlled according to the signal supplied from the controller 33 to the solenoid unit 25B. Therefore, the relief pressure of the pressure control valve 25 can be adjusted, and the pressure of the hydraulic fluid supplied to the rod-side oil chamber 4F2 of the boom cylinder 4F through the rod-side main conduit 28B can be controlled (reduced). A bypass conduit 34 that bypasses the pressure control valve 25 is connected to the additional conduit 32, and a check valve 35 is provided in the bypass conduit 34. The check valve 35 allows the flow of hydraulic fluid from the hydraulic fluid tank 10 toward the main pipe 28B on the rod side, and prevents the flow in the reverse direction.

[0040] The hydraulic excavator 1 according to this embodiment has the configuration described above. When the hydraulic excavator 1 is in operation, the operator rides in the cab 7 and operates the travel lever / pedal device (not shown) to drive the hydraulic excavator 1 to the work site. At the work site, the operator operates the control lever device 31, etc., to rotate the upper slewing body 3 and perform excavation work, etc., using the work device 4.

[0041] When the hydraulic excavator 1 is in operation, if a signal is supplied from the controller 33 to the solenoid section 25B of the pressure control valve 25, the relief pressure of the pressure control valve 25 is adjusted according to this signal (current). As a result, the pressure of the hydraulic fluid supplied to the rod-side oil chamber 4F2 of the boom cylinder 4F through the rod-side main pipeline 28B can be appropriately controlled (reduced).

[0042] If the hydraulic piping (e.g., hydraulic hoses) constituting the hydraulic circuit, including the pressure control valve 25, is replaced, air may enter the hydraulic fluid within the hydraulic circuit. If the air mixed in the hydraulic fluid enters the solenoid section 25B of the pressure control valve 25, the smooth operation of the valve body may be hindered, potentially preventing the pressure control valve 25 from properly adjusting the pressure. In this case, it is necessary to bleed the air from the pressure control valve 25. The following describes this air bleeding procedure.

[0043] First, the worker rotates the front edge 22B of the opening / closing cover 22 that constitutes the outer cover 13 upward around the hinge mechanism 23 (see Figure 4). As a result, the opening 21 of the outer cover 13 is opened, as shown in Figure 2. At this time, the pressure control valve 25 maintains a position in which the solenoid portion 25B faces the opened opening 21. As a result, a worker located outside the upper rotating body 3 can visually inspect the solenoid portion 25B through the opening 21 and easily access the solenoid portion 25B that is subject to maintenance through the opening 21.

[0044] Next, as shown in FIG. 7, the operator removes the sealing plug 25C from the solenoid unit 25B, connects one end of the drain hose 36 to the protruding end of the solenoid unit 25B, and connects the other end of the drain hose 36 to the fuel filler port 10H of the hydraulic oil tank 10. At this time, the solenoid unit 25B of the pressure control valve 25 is disposed between the upper end and the lower end of the opening 21 in the vertical direction, and is inclined obliquely downward and outward of the vehicle body from the main body unit 25A attached to the hydraulic oil tank 10. Thereby, the solenoid unit 25B as a maintenance part can be disposed lower than the upper surface 10A of the hydraulic oil tank 10 and above the fuel tank 11 adjacent to the front side of the hydraulic oil tank 10. As a result, a large working space can be secured above the fuel tank 11, and operations such as removing the sealing plug 25C from the solenoid unit 25B and connecting the drain hose 36 to the protruding end of the solenoid unit 25B can be performed quickly and easily within the large working space. Note that it is not necessary for the entire solenoid unit 25B to be disposed between the upper end and the lower end of the opening 21 and to be inclined obliquely downward and outward of the vehicle body. It is sufficient that at least the protruding end (sealing plug 25C) of the solenoid unit 25B is disposed between the upper end and the lower end of the opening 21 and is inclined obliquely downward and outward of the vehicle body.

[0045] On the other hand, the operator operates the hydraulic pump 9 at a low speed, and introduces the hydraulic oil discharged from the hydraulic pump 9 into the solenoid unit 25B of the pressure control valve 25 through the additional pipe 32. As a result, a part of the hydraulic oil in the hydraulic circuit flows into the hydraulic oil tank 10 from the solenoid unit 25B of the pressure control valve 25 through the drain hose 36. As a result, the air mixed in the hydraulic oil can be separated from the hydraulic oil in the hydraulic oil tank 10. In this case, since the pressure control valve 25 is attached to the hydraulic oil tank 10 via the bracket 24, the distance between the protruding end of the solenoid unit 25B and the fuel filler port 10H of the hydraulic oil tank 10 can be made as small as possible. As a result, the drain hose 36 connecting the two can be shortened, and the air bleeding operation can be performed in a short time by quickly discharging the hydraulic oil mixed with air into the hydraulic oil tank 10 through the drain hose 36.

[0046] After separating the air mixed in the hydraulic fluid from the hydraulic fluid in the hydraulic fluid tank 10 in this manner, one end of the drain hose 36 is removed from the solenoid portion 25B of the pressure control valve 25, and a sealing plug 25C is attached to the protruding end of the solenoid portion 25B. The other end of the drain hose 36 is then removed from the oil inlet 10H of the hydraulic fluid tank 10, and the oil inlet 10H is covered with a lid. Finally, the front edge portion 22B of the opening / closing cover 22 is rotated downward around the hinge mechanism 23 to close the opening 21, thereby completing the air bleeding operation for the pressure control valve 25.

[0047] Thus, the hydraulic excavator 1 according to this embodiment comprises a self-propelled vehicle body, a work device 4 provided on the vehicle body, and a hydraulic actuator for operating the work device 4. The vehicle body includes a slewing frame 5 to which the work device 4 is attached to the front, a hydraulic oil tank 10 mounted on the slewing frame 5 for storing hydraulic oil supplied to the hydraulic actuator, and an exterior cover 13 provided on the slewing frame 5 that forms a tank chamber 20 housing the hydraulic oil tank 10. The tank chamber 20 is provided with an opening 21 that opens to the inside of the tank chamber 20, and the exterior cover 13 has an opening / closing cover 22 that can open and close the opening 21 of the tank chamber 20. Inside the tank chamber 20 is a pressure control valve 25 that has a solenoid section 25B capable of discharging the hydraulic oil and controls the flow of the hydraulic oil supplied to the hydraulic actuator, and the solenoid section 25B of the pressure control valve 25 is positioned between the upper and lower ends of the opening 21 in the vertical direction.

[0048] According to this configuration, an operator performing maintenance on the pressure control valve 25 can visually check the solenoid part 25B from the outside of the upper swivel body 3 through the opening 21. Therefore, the operator can easily access the solenoid part 25B to be maintained through the opening 21, improving the workability of maintenance. Moreover, since the pressure control valve 25 is attached to the hydraulic oil tank 10, the distance between the protruding end of the solenoid part 25B and the oil filling port 10H of the hydraulic oil tank 10 can be made as small as possible. As a result, the drain hose 36 used for the air bleeding operation for the pressure control valve 25 can be shortened, and the hydraulic oil mixed with air can be quickly discharged into the hydraulic oil tank 10 through the drain hose 36, so that the air bleeding operation can be carried out in a short time.

[0049] In the embodiment, the pressure control valve 25 is fixed in a posture where the solenoid part 25B is downward and inclined outward of the vehicle body, and the lower end of the solenoid part 25B is arranged at a position lower than the upper surface 10A of the hydraulic oil tank 10. According to this configuration, the operation of removing the sealing plug 25C from the protruding end (lower end) of the solenoid part 25B during the air bleeding operation can be performed at a position away from the exterior cover 13 downward, improving the workability of maintenance.

[0050] In the embodiment, a fuel tank 11 for storing fuel is provided in the tank chamber 20. The fuel tank 11 is adjacent to the front side of the hydraulic oil tank 10 and is arranged such that the height of the upper surface 11A is lower than the upper surface 10A of the hydraulic oil tank 10. The pressure control valve 25 is attached to the hydraulic oil tank 10, and the solenoid part 25B of the pressure control valve 25 is arranged above the fuel tank 11. According to this configuration, the solenoid part 25B of the pressure control valve 25, which is the object of maintenance, can be arranged above the fuel tank 11 adjacent to the front side of the hydraulic oil tank 10, and a large working space can be secured above the fuel tank 11.

[0051] In this embodiment, the outer cover 13 includes a right front side cover 17 that covers the tank chamber 20 from the side, a right front cover 18 that covers the tank chamber 20 from the front, and a right front top cover 19 that covers the tank chamber 20 from the front and above. The opening 21 is formed by being surrounded by the right front side cover 17, the right front cover 18, and the right front top cover 19. The solenoid portion 25B of the pressure control valve 25 is positioned so that it is covered from the front and above by the right front top cover 19 when the opening / closing cover 22 opens the opening 21. With this configuration, even if hydraulic fluid is scattered from the protruding end of the solenoid portion 25B after the sealing plug 25C has been removed when performing air bleeding work on the pressure control valve 25, this hydraulic fluid can be received by the right front top cover 19, preventing the hydraulic fluid from scattering outside the tank chamber 20.

[0052] In this embodiment, the pressure control valve 25 has an inlet fitting 26 and an outlet fitting 27 connected to an oil passage through which hydraulic fluid flows. The inlet fitting 26 and the outlet fitting 27, together with the solenoid section 25B, are covered from the front and above by a right front upper cover 19. With this configuration, even if hydraulic fluid is ejected from the inlet fitting 26 or the outlet fitting 27, this hydraulic fluid can be received by the right front upper cover 19.

[0053] In the above-described embodiment, the solenoid portion 25B extending downward and outward from the main body 25A of the pressure control valve 25 is shown as being inclined at an angle θ1 with respect to the vertical. However, the present invention is not limited to this, and for example, as shown in the modified example in Figure 9, the inclination of the solenoid portion 25B with respect to the vertical may be set to an angle θ2 that is larger than the angle θ1 (θ2 > θ1). With this configuration, the distance between the protruding end of the solenoid portion 25B and the upper surface 11A of the fuel tank 11 is increased, and the working space formed above the fuel tank 11 can be increased, thereby further improving the workability of maintenance.

[0054] Furthermore, in this embodiment, when performing air bleeding work on the pressure control valve 25, the hydraulic fluid discharged from the protruding end of the solenoid section 25B is returned to the hydraulic fluid tank 10 via the drain hose 36. However, the present invention is not limited to this, and for example, an oil pan or the like may be placed below the protruding end of the solenoid section 25B to separate any air mixed in when the hydraulic fluid is discharged from the solenoid section 25B to the oil pan or the like.

[0055] In this embodiment, the pressure control valve 25 is used to adjust the pressure of the hydraulic fluid supplied to the boom cylinder 4F. However, the present invention is not limited to this, and may also be used to adjust the pressure of the hydraulic fluid supplied to other hydraulic actuators, such as the arm cylinder 4G and the bucket cylinder 4H.

[0056] Furthermore, the embodiment illustrates a case where the solenoid portion 25B of the pressure control valve 25 is inclined at an angle θ1 with respect to the vertical. However, the present invention is not limited to this, and for example, the solenoid portion may be arranged to extend horizontally.

[0057] 2 Lower running body (vehicle body) 3 Upper slewing body (vehicle body) 4 Working equipment 4F Boom cylinder (hydraulic actuator) 5 Slewing frame (vehicle frame) 10 Hydraulic oil tank (oil storage tank) 10A, 11A Top view 11 Fuel tank (oil storage tank) 13 Exterior cover 17 Right front side cover (side cover) 17A Side cover section 17B Front cover section 18 Right front cover (front cover section) 19 Right front top cover (top cover section) 20 Tank compartment 21 Opening 22 Opening / closing cover 25 Pressure control valve (control valve) 25B Solenoid section (maintenance section) 26 Inlet joint (inlet) 27 Outlet joint (outlet)

Claims

1. A construction machine comprising a self-propelled vehicle body, a work device provided on the vehicle body, and a hydraulic actuator for operating the work device, wherein the vehicle body comprises a vehicle frame on which the work device is attached to the front, a hydraulic oil tank mounted on the vehicle frame for storing hydraulic oil supplied to the hydraulic actuator, and an exterior cover provided on the vehicle frame for forming a tank chamber that houses the hydraulic oil tank, wherein the tank chamber is provided with an opening that opens to the inside of the tank chamber, and the exterior cover has an opening / closing cover that opens and closes the opening of the tank chamber, wherein the inside of the tank chamber is provided with a control valve that controls the flow of hydraulic oil supplied to the hydraulic actuator and has a maintenance section for discharging the hydraulic oil, and the maintenance section of the control valve is positioned vertically between the upper end and the lower end of the opening.

2. The construction machine according to claim 1, characterized in that the control valve is fixed in a position in which the maintenance section is inclined downward and outward toward the vehicle body, and the lower end of the maintenance section is positioned lower than the upper surface of the hydraulic oil tank.

3. The construction machine according to claim 1, comprising a fuel tank provided in the tank chamber for storing fuel, wherein the fuel tank is adjacent to the front of the hydraulic oil tank and is positioned such that the height of its upper surface is lower than the height of the hydraulic oil tank, the control valve is attached to the hydraulic oil tank, and the maintenance part of the control valve is positioned above the fuel tank.

4. The exterior cover comprises a side cover portion that covers the tank chamber from the side, a front cover portion that covers the tank chamber from the front, and a front top cover portion that covers the tank chamber from the front and above, the opening is formed by being surrounded by the side cover portion, the front cover portion, and the front top cover portion, and the maintenance portion of the control valve is positioned so that it is covered from the front and above by the front top cover portion when the opening / closing cover is open, as described in claim 1.

5. The construction machine according to claim 4, wherein the control valve has an inlet and an outlet connected to an oil passage through which the hydraulic fluid flows, and the inlet and the outlet are covered from the front and above by the front upper cover together with the maintenance section.

Images