Work machine

Abstract

To provide a work machine capable of quickly increasing a temperature of hydraulic oil supplied to an actuator.SOLUTION: A work machine includes an engine, a cooling fan, a radiator, a hydraulic oil tank, a hydraulic pump, and a hydraulic actuator. The hydraulic oil tank comprises: a storage chamber that forms a space for storing hydraulic oil; an inlet portion that allows hydraulic oil returned from the hydraulic actuator to flow into the storage chamber; an outlet portion that allows the hydraulic oil stored in the storage chamber to flow toward the hydraulic pump; and a filter that is connected to the outlet portion within the storage chamber and removes dust from the hydraulic oil flowing out through the outlet portion. There is provided a heating flow path through which coolant circulating between the engine and the radiator flows, and which is inserted into the storage chamber. The heating flow path has a heat exchange portion formed to surround the filter within the storage chamber.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a work machine. [Background technology]

[0002] Conventionally, there has been known a work machine that includes a radiator that exchanges heat between engine coolant and cooling air from a cooling fan, and a hydraulic oil tank that stores hydraulic oil that operates a hydraulic actuator (see, for example, Patent Document 1).

[0003] Here, the lower the temperature of the hydraulic oil, the higher its viscosity, which leads to poorer response of the hydraulic actuator. Therefore, when starting a work machine in cold regions, it is necessary to perform a warm-up operation to heat the hydraulic oil until the temperature of the hydraulic oil reaches an appropriate range. In other words, in cold regions, the warm-up operation takes time, which reduces the productivity of the work machine.

[0004] Therefore, Patent Document 1 discloses a technology in which when the temperature of the radiator coolant is higher than the temperature of the hydraulic oil in the hydraulic oil tank, heat is exchanged between the radiator coolant and the hydraulic oil in the hydraulic oil tank to heat the hydraulic oil. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-133175 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, because the amount of hydraulic oil in the hydraulic oil tank is significantly greater than the amount of coolant in the radiator, it is difficult to heat all of the hydraulic oil in the hydraulic oil tank in a short period of time. Furthermore, even if the temperature of some of the hydraulic oil in the hydraulic oil tank can be raised, the responsiveness of the hydraulic actuator will not improve unless the temperature of the hydraulic oil supplied to the actuator is also raised.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a work machine that is capable of quickly increasing the temperature of hydraulic oil supplied to an actuator. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a working machine comprising an engine, a cooling fan that generates cooling air, a radiator that exchanges heat between a coolant for the engine and the cooling air of the cooling fan, a hydraulic oil tank that stores hydraulic oil, a hydraulic pump that pumps out the hydraulic oil stored in the hydraulic oil tank, and a hydraulic actuator that operates with the hydraulic oil supplied from the hydraulic pump, wherein the hydraulic oil tank has a storage chamber that forms a space for storing the hydraulic oil, an inlet portion that allows the hydraulic oil returned from the hydraulic actuator to flow into the storage chamber, an outlet portion that allows the hydraulic oil stored in the storage chamber to flow toward the hydraulic pump, and a filter that is connected to the outlet portion within the storage chamber and removes dust from the hydraulic oil that flows out through the outlet portion, the working machine being characterized in that the cooling liquid circulating between the engine and the radiator flows through a heating flow path that is inserted into the storage chamber, and the heating flow path has a heat exchange portion formed to surround the filter within the storage chamber. Effect of the Invention

[0009] According to the present invention, it is possible to obtain a work machine that is capable of quickly increasing the temperature of the hydraulic oil supplied to the actuator. Note that problems, configurations, and effects other than those described above will become apparent from the description of the embodiments below. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a side view of the hydraulic excavator. [Diagram 2] FIG. 2 is a schematic diagram of a drive circuit of a hydraulic excavator. [Diagram 3] FIG. 2 is an external perspective view of a hydraulic oil tank. [Figure 4]FIG. 2 is a left-front perspective view of the hydraulic oil tank with the left side wall omitted. [Diagram 5] FIG. 2 is a left rear perspective view of the hydraulic oil tank with the left side wall omitted. [Figure 6] FIG. 4 is a left side view of the hydraulic oil tank with the left side wall omitted. [Figure 7] 4 is a schematic cross-sectional view of an outflow section, a suction filter, and a heating flow path. FIG. [Figure 8] FIG. 2 is a hardware configuration diagram of a hydraulic excavator. [Figure 9] 4 is a flowchart of a warm-up process. [Figure 10] FIG. 4 is a diagram showing the relationship between the temperature of hydraulic oil and the distribution ratio of coolant to the hydraulic oil tank side. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] An embodiment of a hydraulic excavator 1 (working machine) according to the present invention will be described with reference to the drawings. Note that specific examples of the working machine are not limited to the hydraulic excavator 1, and may be a wheel loader, a crane, a dump truck, etc. Furthermore, unless otherwise specified, the terms front, back, left, and right in this specification are based on the viewpoint of an operator who is on board and operating the hydraulic excavator 1.

[0012] [Overall configuration of hydraulic excavator 1] FIG. 1 is a side view of a hydraulic excavator 1. As shown in FIG. 1, the hydraulic excavator 1 includes a lower traveling body 2 and an upper rotating body 3 supported by the lower traveling body 2. The lower traveling body 2 and the upper rotating body 3 are an example of a vehicle body. The lower traveling body 2 includes a pair of left and right crawlers 4 which are endless tracks. The pair of left and right crawlers 4 are rotated independently by driving a traveling motor 5. As a result, the hydraulic excavator 1 travels. However, the lower traveling body 2 may be of a wheeled type instead of the crawlers 4.

[0013] The upper rotating body 3 is supported on the lower traveling body 2 so as to be rotatable by a rotating motor 6. The upper rotating body 3 mainly comprises a rotating frame 7 serving as a base, a cab (operator's seat) 8 disposed on the front left side of the rotating frame 7, a counterweight 9 disposed at the rear of the rotating frame 7, and a front work machine 10 (work device) attached to the front center of the rotating frame 7 so as to be rotatable in the vertical direction.

[0014] The cab 8 defines a space for an operator to ride in and operate the hydraulic excavator 1. Inside the cab 8, there are a seat on which the operator sits and an operating device operated by the operator seated on the seat. The operating device receives operations by the operator to operate the hydraulic excavator 1. When the operator operates the operating device, the lower traveling body 2 travels, the upper rotating body 3 rotates, and the front working implement 10 operates. Specific examples of the operating device include a lever, a steering wheel, a pedal, and a switch.

[0015] The front working implement 10 includes a boom 11 supported on the upper rotating body 3 so as to be able to rise and fall, an arm 12 supported rotatably at the end of the boom 11, a bucket 13 supported rotatably at the end of the arm 12, a boom cylinder 14 that drives the boom 11, an arm cylinder 15 that drives the arm 12, and a bucket cylinder 16 that drives the bucket 13. The counterweight 9 is used to balance the weight of the front working implement 10, and is a heavy object that has an arc shape when viewed from above.

[0016] [Configuration of driving circuit 20] Fig. 2 is a schematic diagram of a drive circuit 20 of the hydraulic excavator 1. The hydraulic excavator 1 includes the drive circuit 20 shown in Fig. 2. The drive circuit 20 is a circuit that drives hydraulic actuators (the travel motor 5, the swing motor 6, the boom cylinder 14, the arm cylinder 15, and the bucket cylinder 16).

[0017] 2, the drive circuit 20 includes an engine 21, a cooling fan 22, a radiator 23, a temperature sensor 24, a three-way valve 25, a hydraulic oil tank 26, a hydraulic pump 27, and an oil cooler 28. The drive circuit 20 also includes a cooling flow path L1, a heating flow path L2, and a hydraulic oil flow path L3. The cooling flow path L1, the heating flow path L2, and the hydraulic oil flow path L3 are configured with metal or resin piping, flexible hoses, or a combination of these.

[0018] The cooling flow path L1 is a flow path for circulating the coolant between the engine 21 and the radiator 23. In other words, the cooling flow path L1 is a flow path for the coolant that returns from the radiator 23 to the radiator 23 via the engine 21 and the three-way valve 25. More specifically, the cooling flow path L1 supplies the coolant that has been heat exchanged in the radiator 23 to the engine 21, and returns the coolant that has been heated by cooling the engine 21 to the radiator 23 via the three-way valve 25.

[0019] The heating flow path L2 is a flow path through which the coolant circulating between the engine 21 and the radiator 23 flows. The heating flow path L2 is inserted into the storage chamber 30. The heating flow path L2 is a flow path for the coolant that branches off from the cooling flow path L1 at the position of the three-way valve 25 and returns to the radiator 23 via the hydraulic oil tank 26. More specifically, the heating flow path L2 supplies the coolant that has been heated by cooling the engine 21 to the hydraulic oil tank 26 via the three-way valve 25, and returns the coolant that has heated the hydraulic oil stored in the hydraulic oil tank 26 to the radiator 23.

[0020] The hydraulic oil flow path L3 is a flow path that circulates hydraulic oil between the hydraulic oil tank 26 and the hydraulic actuators (5, 6, 14, 15, 16). In other words, the hydraulic oil flow path L3 is a flow path for hydraulic oil that returns to the hydraulic oil tank 26 from the hydraulic oil tank 26 via the hydraulic pump 27, the hydraulic actuators (5, 6, 14, 15, 16), and the oil cooler 28. More specifically, the hydraulic oil flow path L3 supplies the hydraulic oil stored in the hydraulic oil tank 26 to the hydraulic actuators (5, 6, 14, 15, 16) via the hydraulic pump 27, and returns the hydraulic oil that has operated the hydraulic actuators (5, 6, 14, 15, 16) to the hydraulic oil tank 26 via the oil cooler 28.

[0021] The engine 21 generates driving force for operating the hydraulic excavator 1 by mixing and burning fossil fuel and air. The cooling fan 22 generates cooling air toward the radiator 23 and the oil cooler 28 by rotating when the driving force of the engine 21 is transmitted to it. Note that the cooling fan 22 may be rotated by the driving force of an electric motor or a hydraulic motor instead of by the driving force of the engine 21.

[0022] The radiator 23 exchanges heat between the coolant flowing through the cooling flow path L1 and the heating flow path L2 and the cooling air generated by the cooling fan 22. More specifically, the radiator 23 maintains the temperature of the coolant within an appropriate range by exchanging heat between the coolant that has cooled the engine 21 and the coolant that has heated the hydraulic oil stored in the hydraulic oil tank 26 and the cooling air generated by the cooling fan 22. The temperature sensor 24 detects the temperature of the coolant that has been heated by cooling the engine 21 (i.e., the coolant passing through the cooling flow path L1) and outputs a temperature signal indicating the detected temperature to the controller 50 described later.

[0023] The three-way valve 25 is disposed at a branching position of the cooling flow path L1 and the heating flow path L2. The three-way valve 25 supplies the coolant heated by cooling the engine 21 to one or both of the radiator 23 and the hydraulic oil tank 26 under the control of the controller 50. More specifically, the three-way valve 25 adjusts the distribution ratio between the hydraulic oil that is returned directly to the radiator 23 and the coolant that is returned to the radiator 23 via the hydraulic oil tank 26 under the control of the controller 50.

[0024] The hydraulic oil tank 26 stores hydraulic oil for operating the hydraulic actuators (5, 6, 14, 15, 16). The hydraulic oil tank 26 also removes dust contained in the hydraulic oil stored therein. The hydraulic oil tank 26 also exchanges heat between the hydraulic oil stored therein and the cooling liquid passing through the heating flow path L2. A detailed configuration of the hydraulic oil tank 26 will be described later with reference to FIGS. 3 to 7.

[0025] The hydraulic pump 27 is connected to the output shaft of the engine 21 and rotates to pump the hydraulic oil stored in the hydraulic oil tank 26 toward the hydraulic actuators (5, 6, 14, 15, 16). The hydraulic pump 27 is a variable displacement type that can change the pump displacement per rotation under the control of the controller 50.

[0026] The hydraulic actuators (5, 6, 14, 15, 16) operate (rotate, expand and contract) using hydraulic oil supplied from a hydraulic pump 27. In addition, the hydraulic oil that has operated the hydraulic actuators is returned to the hydraulic oil tank 26 through an oil cooler 28. The oil cooler 28 exchanges heat between the hydraulic oil discharged from the hydraulic actuators (5, 6, 14, 15, 16) and the cooling air generated by a cooling fan 22, thereby maintaining the temperature of the hydraulic oil within an appropriate range.

[0027] [Configuration of hydraulic oil tank 26] Fig. 3 is an external perspective view of the hydraulic oil tank 26. Fig. 4 is a left front perspective view of the hydraulic oil tank 26 with the left side wall 36 omitted. Fig. 5 is a left rear perspective view of the hydraulic oil tank 26 with the left side wall 36 omitted. Fig. 6 is a left side view of the hydraulic oil tank 26 with the left side wall 36 omitted. Fig. 7 is a schematic cross-sectional view of the outflow portion 39, the suction filter 40, and the heating flow path L2.

[0028] As shown in Figures 3 to 6, the hydraulic oil tank 26 includes a storage chamber 30, a bottom wall 31, a top wall 32, a front wall 33, a rear wall 34, a right side wall 35, a left side wall 36, support mounts 37a, 37b, an inlet section 38, an outlet section 39, a suction filter 40 (filter), an oil temperature sensor 41, a first partition 42, and a second partition 43.

[0029] The storage chamber 30 forms a space for storing hydraulic oil. The storage chamber 30 is defined by a bottom wall 31, a top wall 32, a front wall 33, a rear wall 34, a right side wall 35, and a left side wall 36. In addition to the hydraulic oil, the storage chamber 30 also accommodates an inlet section 38, an outlet section 39, a suction filter 40, an oil temperature sensor 41, a first partition 42, a second partition 43, and a heat exchange section 44 which is a part of the heating flow path L2.

[0030] The bottom wall 31 defines the bottom surface of the storage chamber 30. The top wall 32 defines the top surface of the storage chamber 30. The front wall 33 defines the front surface of the storage chamber 30. The rear wall 34 defines the rear surface of the storage chamber 30. The right side wall 35 defines the right side surface of the storage chamber 30. The left side wall 36 defines the left side surface of the storage chamber 30. In this embodiment, the bottom wall 31, the right side wall 35, and the left side wall 36 are integrally formed by bending a flat plate, and the top wall 32, the front wall 33, and the rear wall 34 are integrally formed. In addition, the upper parts of the front wall 33 and the rear wall 34 are inclined in a direction approaching each other. However, the shape of the outer wall (31 to 36) of the hydraulic oil tank 26 that defines the storage chamber 30 is not limited to the above example.

[0031] The support mounts 37a, 37b are portions that are placed on the hydraulic excavator 1 (more specifically, the upper rotating body 3). The support mounts 37a, 37b are fixed to the lower surface of the bottom wall 31. The support mounts 37a, 37b are disposed spaced apart in the front-rear direction. The support mounts 37a, 37b are fastened to the upper rotating body 3 with bolts (not shown), thereby fixing the hydraulic oil tank 26 to the upper rotating body 3.

[0032] The bottom wall 31 according to this embodiment has a rectangular shape having a long side and a short side. The hydraulic oil tank 26 is installed on the upper rotating body 3 so that the long side of the bottom wall 31 faces the front-rear direction and the short side of the bottom wall 31 faces the left-right direction. That is, the storage chamber 30 has a flat shape whose size in the front-rear direction is longer than its size in the left-right direction. However, the orientation of the hydraulic oil tank 26 with respect to the upper rotating body 3 is not limited to the above example.

[0033] The inlet portion 38 is a portion that allows the hydraulic oil that has returned from the hydraulic actuators (5, 6, 14, 15, 16) through the hydraulic oil flow path L3 to flow into the storage chamber 30. The inlet portion 38 is a tubular (more specifically, cylindrical) member that extends downward from the lower surface of the top wall 32.

[0034] An opening 38a is formed at the lower end of the inlet 38, allowing the hydraulic oil supplied to the inlet 38 to flow into the storage chamber 30. The opening 38a is disposed above the bottom wall 31. A cap 38b for opening and closing the upper end of the inlet 38 is detachably provided on the upper surface of the top wall 32. A filter (not shown) for removing dust from the hydraulic oil that has flowed into the inlet 38 is filled inside the inlet 38. A downstream end of the hydraulic oil flow path L3 penetrating the bottom wall 31 is connected to the side surface of the inlet 38.

[0035] The outflow part 39 is a part that causes the hydraulic oil stored in the storage chamber 30 to flow out toward the hydraulic pump 27. The outflow part 39 is a tubular (more specifically, cylindrical) member that penetrates the bottom wall 31. The outflow part 39 is provided inside the storage chamber 30 and extends upward from the bottom wall 31. A suction filter 40 is attached to the upper end of the outflow part 39 (the upstream end of the hydraulic oil flow). Furthermore, the upstream end of the hydraulic oil flow path L3 in the hydraulic oil flow is connected to a part of the outflow part 39 outside the storage chamber 30 (i.e., below the bottom wall 31).

[0036] The hydraulic oil supplied to the inlet 38 through the hydraulic oil flow path L3, or the hydraulic oil replenished to the inlet 38 after removing the cap 38b, flows into the storage chamber 30 through the opening 38a after dust is removed by the filter. In addition, the hydraulic oil stored in the storage chamber 30 flows out of the hydraulic oil flow path L3 through the outlet 39 after dust is removed by the suction filter 40.

[0037] The suction filter 40 is disposed at a position spaced upward from the bottom wall 31. The suction filter 40 has, for example, a cylindrical outer shape. The suction filter is connected to the upper end of the outlet portion 39 in the storage chamber 30 with the axial direction of the cylindrical shape facing the up-down direction. The suction filter 40 removes dust from the hydraulic oil flowing out through the outlet portion 39. In other words, the hydraulic oil stored in the storage chamber 30 flows out of the hydraulic oil tank 26 through the outlet portion 39 after passing through the suction filter 40.

[0038] The oil temperature sensor 41 detects the temperature of the hydraulic oil stored in the storage chamber 30, and outputs a temperature signal indicating the detected temperature to the controller 50. The oil temperature sensor 41 is attached to the upper surface of the bottom wall 31, for example.

[0039] The inflow section 38, the outflow section 39, and the oil temperature sensor 41 are disposed at positions spaced apart in the longitudinal direction of the bottom wall 31 inside the storage chamber 30. In this embodiment, the inflow section 38 is disposed rearward of the outflow section 39, and the oil temperature sensor 41 is disposed forward of the outflow section 39. In other words, the inflow section 38 and the oil temperature sensor 41 are disposed on opposite sides of the outflow section 39 in the longitudinal direction of the bottom wall 31. In further other words, the outflow section 39 is disposed between the inflow section 38 and the oil temperature sensor 41 in the longitudinal direction of the bottom wall 31. However, the positional relationship between the inflow section 38, the outflow section 39, and the oil temperature sensor 41 is not limited to the above example.

[0040] The first partition 42 is connected to the inner surfaces of the bottom wall 31, the top wall 32, the right side wall 35, and the left side wall 36. The first partition 42 is disposed between the inlet portion 38 and the outlet portion 39 in the longitudinal direction of the bottom wall 31. That is, the first partition 42 separates the storage chamber 30 in the longitudinal direction of the bottom wall 31 between the inlet portion 38 and the outlet portion 39 (more specifically, the suction filter 40).

[0041] The first partition wall 42 has an upper opening 42a and a lower opening 42b penetrating in the thickness direction. The upper opening 42a is provided in the upper part of the first partition wall 42. More specifically, the lower end of the upper opening 42a is located above the upper end of the opening 38a and the lower end of the suction filter 40. The lower end of the upper opening 42a is located below a predetermined full position P. The full position P is, for example, an upper limit position of the oil level of the hydraulic oil determined by design, and is a position below the lower surface of the top wall 32. The lower opening 42b is provided in the lower part of the first partition wall 42. The position of the lower opening 42b may be any position below the upper opening 42a, and is typically the lower end of the first partition wall 42 that contacts the bottom wall 31. The opening area of ​​the upper opening 42a is larger than the opening area of ​​the lower opening 42b.

[0042] The second partition 43 is connected to the inner surfaces of the bottom wall 31, the top wall 32, the right side wall 35, and the left side wall 36. The second partition 43 is disposed between the outflow portion 39 and the oil temperature sensor 41 in the longitudinal direction of the bottom wall 31. That is, the second partition 43 separates the storage chamber 30 in the longitudinal direction of the bottom wall 31 between the outflow portion 39 (more specifically, the suction filter 40) and the oil temperature sensor 41.

[0043] The second partition wall 43 has an upper opening 43a and a lower opening 43b formed therethrough in the thickness direction. The upper opening 43a is provided in the upper part of the second partition wall 43. More specifically, the lower end of the upper opening 43a is located above the lower end of the suction filter 40 (more preferably, the upper end of the suction filter 40). The lower end of the upper opening 43a is located below the full-capacity position P. The lower opening 43b is provided in the lower part of the second partition wall 43. The position of the lower opening 43b may be any position below the upper opening 43a, and is typically the lower end of the second partition wall 43 that contacts the bottom wall 31. The opening area of ​​the upper opening 43a is larger than the opening area of ​​the lower opening 43b.

[0044] That is, the first partition 42 and the second partition 43 are arranged in the storage chamber 30 with a space therebetween in the front-rear direction. The first partition 42 and the second partition 43 separate the storage chamber 30 into three spaces adjacent in the front-rear direction. Hereinafter, the space in front of the second partition 43 of the storage chamber 30 is referred to as the "front space", the space between the first partition 42 and the second partition 43 is referred to as the "center space", and the space behind the first partition 42 is referred to as the "rear space". That is, the center space and the rear space are separated by the first partition 42 and communicate with each other through the upper opening 42a and the lower opening 42b. The front space and the center space are separated by the second partition 43 and communicate with each other through the upper opening 43a and the lower opening 43b.

[0045] In addition, the specific shapes of the upper openings 42a, 43a and the lower openings 42b, 43b are not particularly limited as long as they penetrate the first partition 42 and the second partition 43, and they may be in the form of a so-called "hole" or a so-called "notch".

[0046] The heating flow passage L2 is a flow passage that extends from the radiator 23 to the storage chamber 30, is disposed so as to surround the suction filter 40 inside the storage chamber 30, and returns to the radiator 23. More specifically, the heating flow passage L2 penetrates the bottom wall 31, enters the storage chamber 30, extends upward, reaches the upper end while surrounding the suction filter 40, extends downward from the upper end, penetrates the bottom wall 31, and exits the storage chamber 30. However, the wall through which the heating flow passage L2 enters and exits the storage chamber 30 is not limited to the bottom wall 31. The portion of the heating flow passage L2 formed so as to surround the suction filter 40 constitutes a heat exchanger 44 that exchanges heat between the coolant passing through the heating flow passage L2 and the hydraulic oil stored in the storage chamber 30.

[0047] The heat exchanger 44 surrounds a part of the suction filter 40. The heat exchanger 44 according to this embodiment surrounds the side surface of the suction filter 40, but does not surround the upper and lower surfaces of the suction filter 40. The heat exchanger 44 according to this embodiment is formed in a spiral shape so as to surround the suction filter 40. More specifically, the heat exchanger 44 extends upward in a spiral shape along the outer circumferential surface of the suction filter 40.

[0048] 7, the heat exchanger 44 is disposed at a position radially spaced from the outer circumferential surface of the suction filter 40. The heat exchanger 44 extends in a spiral shape at a predetermined interval in the vertical direction. That is, the hydraulic oil stored in the storage chamber 30 passes between the spiral heat exchanger 44 from the outside to the inside and reaches the suction filter 40.

[0049] Furthermore, the cross-sectional shape of the heat exchanger 44 perpendicular to the flow direction of the coolant may be a perfect circle (FIG. 7(A)) or a flat shape (FIG. 7(B)). More specifically, the cross-sectional shape of the heat exchanger 44 shown in FIG. 7(B) is a flat shape that is long in the radial direction of the suction filter 40 (in other words, the direction of the flow of the hydraulic oil passing between the spiral heat exchanger 44) and short in the axial direction of the suction filter 40 (i.e., the up-down direction).

[0050] In the hydraulic oil tank 26 configured as described above, the hydraulic oil that flows into the storage chamber 30 through the opening 39a of the outflow section 39 is diffused throughout the storage chamber 30 through the upper openings 42a, 43a and the lower openings 42b, 43b. Here, the hydraulic oil cooled by the oil cooler 28 is stored first in the rear space. The hydraulic oil in the central space is heated by the cooling liquid passing through the heat exchanger 44. Therefore, within the storage chamber 30, the temperature of the hydraulic oil in the central space is the highest, the temperature of the hydraulic oil in the rear space is the lowest, and the temperature of the hydraulic oil in the front space is intermediate between them.

[0051] Next, as the hydraulic pump 27 rotates, the hydraulic oil stored in the storage chamber 30 (more specifically, the central space) passes between the spiral heat exchanger 44, has dust removed by the suction filter 40, and flows out into the hydraulic oil flow path L3 through the outlet 39. Furthermore, the hydraulic oil that has flowed out into the hydraulic oil flow path L3 is supplied to the hydraulic actuators (5, 6, 14, 15, 16) by the hydraulic pump 2727, and after operating the hydraulic actuators (5, 6, 14, 15, 16), returns to the hydraulic oil tank 26 through the oil cooler 28.

[0052] [Controller 50 Configuration] FIG. 8 is a hardware configuration diagram of the hydraulic excavator 1. The hydraulic excavator 1 includes a controller 50. The controller 50 includes a CPU (Central Processing Unit) 51 and a memory 52. ​​The memory 52 is configured, for example, with a ROM (Read Only Memory), a RAM (Random Access Memory), a HDD (Hard Disk Drive), or a combination of these. The controller 50 realizes processing, which will be described later, by the CPU 51 reading and executing program code stored in the ROM or HDD. The RAM is used as a work area when the CPU 51 executes a program.

[0053] However, the specific configuration of the controller 50 is not limited to this, and may be realized by hardware such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA).

[0054] The controller 50 controls the overall operation of the hydraulic excavator 1. More specifically, the controller 50 acquires temperature signals from the temperature sensor 24 and the oil temperature sensor 41, and controls the operations of the engine 21, the cooling fan 22, the three-way valve 25, and the hydraulic pump 27. The controller 50 according to this embodiment adjusts the amount of coolant circulating through the heating flow path L2, particularly based on the temperature detected by the oil temperature sensor 41.

[0055] [Warm-up process] Fig. 9 is a flowchart of the warm-up process. Fig. 10 is a diagram showing the relationship between the temperature of the hydraulic oil and the distribution ratio of the coolant to the hydraulic oil tank 26. The controller 50 starts the warm-up process shown in Fig. 9, for example, when the engine 21 starts. At the start of the warm-up process, it is assumed that the engine 21 starts, the cooling fan 22 is rotating, the three-way valve 25 supplies the coolant only to the radiator 23, and the pump capacity of the hydraulic pump 27 is set to the minimum.

[0056] In this embodiment, the upper limit value of the variable n is set to 3. The distribution ratios of the three-way valve 25 to the radiator 23 side and the hydraulic oil tank 26 side are set to a first ratio=70:30, a second ratio=80:20, and a third ratio=90:10. That is, the distribution ratios to the hydraulic oil tank 26 side are first ratio>second ratio>third ratio. The first threshold value<second threshold value<third threshold value, and the lowest temperature of the hydraulic oil at which the viscosity is suitable for driving the hydraulic actuators (5, 6, 14, 15, 16) is set to the third threshold value. However, the upper limit value of the variable n, and the specific values ​​of the first ratio, the second ratio, the third ratio, the first threshold value, the second threshold value, and the third threshold value are not limited to the above-mentioned examples.

[0057] First, the controller 50 compares the temperature of the coolant detected by the temperature sensor 24 with the temperature of the hydraulic oil detected by the oil temperature sensor 41. Then, the controller 50 waits to execute the processes in step S12 and thereafter until the temperature of the coolant becomes higher than the temperature of the hydraulic oil (S11: No). As a result, the coolant circulating through the cooling flow path L1 is heated by the engine 21 and the temperature gradually increases. Meanwhile, because the pump capacity of the hydraulic pump 27 is set to the minimum, the amount of hydraulic oil circulating through the hydraulic oil flow path L3 is close to zero, and the temperature of the hydraulic oil hardly increases.

[0058] Next, when the temperature of the coolant becomes higher than the temperature of the hydraulic oil (S11: Yes), the controller 50 initializes (=1) the variable n stored in the memory 52 (S12) and sets the distribution ratio of the three-way valve 25 to the n-th ratio (S13). As a result, the coolant heated by the engine 21 circulates through the heating flow path L2 and exchanges heat with the hydraulic oil stored in the hydraulic oil tank 26 in the heat exchanger 44 (i.e., warms the hydraulic oil).

[0059] Next, the controller 50 waits to execute the processes in and after step S15 (in other words, maintains the state of step S13) until the temperature of the hydraulic oil detected by the oil temperature sensor 41 reaches the n-th threshold (S14: No). Then, when the temperature of the hydraulic oil detected by the oil temperature sensor 41 reaches the n-th threshold (S14: Yes), the controller 50 determines whether the variable n has reached an upper limit value (S15).

[0060] Next, when the controller 50 determines that the variable n has not reached the upper limit value (S15: No), it adds 1 to the variable n (S16) and executes the processes from step S13 onwards again. That is, the controller 50 repeatedly executes the processes of steps S13-S14 while incrementing the variable n until the variable n reaches the upper limit value (S15: No). Then, when the controller 50 determines that the variable n has reached the upper limit value (S15: Yes), it switches the three-way valve 25 so that the coolant is supplied only to the radiator 23 side, and ends the warm-up process. After this, the capacity of the hydraulic pump 27 changes according to the operation of the operating device by the operator. As a result, the hydraulic actuators (5, 6, 14, 15, 16) are operated by the hydraulic oil pumped by the hydraulic pump 27.

[0061] In this embodiment, the distribution ratio of the three-way valve 25 is set to a first ratio while the temperature of the hydraulic oil is below a first threshold, the distribution ratio of the three-way valve 25 is set to a second ratio while the temperature of the hydraulic oil is equal to or greater than the first threshold and less than a second threshold, and the distribution ratio of the three-way valve 25 is set to a third ratio while the temperature of the hydraulic oil is equal to or greater than the second threshold and less than a third threshold.

[0062] That is, as shown in Fig. 10, the higher the temperature of the hydraulic oil detected by the oil temperature sensor 41, the more the controller 50 controls the three-way valve 25 to reduce the amount of cooling liquid circulating through the heating flow path L2 (i.e., the distribution ratio). Note that, although the distribution ratio is set to three stages in the above embodiment, the distribution ratio may be switched more finely.

[0063] According to this embodiment, for example, the following advantageous effects are obtained.

[0064] According to the above embodiment, the temperature of the hydraulic oil in the hydraulic oil tank 26 can be quickly increased by supplying the coolant heated by the engine 21 to the heat exchanger 44 surrounding the suction filter 40 in the hydraulic oil tank 26. This shortens the warm-up time (i.e., downtime), thereby preventing a decrease in the productivity of the hydraulic excavator 1.

[0065] Furthermore, according to the above embodiment, the heat exchanger 44 is configured in a spiral shape so as to surround the suction filter 40, thereby increasing the contact area between the heat exchanger 44 and the hydraulic oil. This allows the temperature of the hydraulic oil to be increased more quickly.

[0066] Furthermore, according to the above embodiment, by providing the first partition 42 between the inlet portion 38 and the suction filter 40, it is possible to prevent the hydraulic oil around the suction filter 40 heated by the heat exchanger 44 from mixing with the low-temperature hydraulic oil flowing in from the inlet portion 38. This makes it possible to increase the temperature of the hydraulic oil even more quickly.

[0067] In addition, according to the above embodiment, by providing a second partition 43 between the suction filter 40 and the oil temperature sensor 41, it is possible to prevent the hydraulic oil around the suction filter 40 heated by the heat exchange section 44 from reaching the oil temperature sensor 41, which would cause the oil temperature sensor 41 to detect a temperature higher than the average temperature of the hydraulic oil in the storage chamber 30.

[0068] Furthermore, according to the above embodiment, by forming the upper openings 42a, 43a in the first partition 42 and the second partition 43 above the lower end of the suction filter 40 and below the full-volume position P, it is possible to circulate the hydraulic oil between the front region, the central region, and the rear region while suppressing the diffusion of heated hydraulic oil around the suction filter 40. Furthermore, by forming the lower openings 42b, 43b in the lower ends of the first partition 42 and the second partition 43, it is possible to maintain the circulation of the hydraulic oil between the front region, the central region, and the rear region even if the amount of hydraulic oil in the storage chamber 30 decreases.

[0069] Furthermore, according to the above embodiment, the cross-sectional shape of the heat exchanger 44 is flattened, thereby reducing the resistance when the hydraulic oil passes through the heat exchanger 44 and increasing the contact area between the heat exchanger 44 and the hydraulic oil. This allows the temperature of the hydraulic oil to be increased more quickly.

[0070] Furthermore, according to the above embodiment, the amount of coolant circulating through the heating flow path L2 is reduced as the temperature of the hydraulic oil increases, thereby making it possible to quickly increase the temperature of the hydraulic oil while preventing the engine 21 from overheating.

[0071] The above-described embodiments are illustrative examples of the present invention, and are not intended to limit the scope of the present invention to these embodiments. Those skilled in the art can implement the present invention in various other forms without departing from the gist of the present invention. [Explanation of symbols]

[0072] 1: Hydraulic excavator (working machine) 2: Lower running body 3: Upper rotating body 4: Crawler 5: Travel motor (hydraulic actuator) 6: Swing motor (hydraulic actuator) 7: Swivel frame 8: Cab 9: Counterweight 10: Front work machine 11: Boom 12: Arm 13: Bucket 14: Boom cylinder (hydraulic actuator) 15: Arm cylinder (hydraulic actuator) 16: Bucket cylinder (hydraulic actuator) 20: Drive circuit 21: Engine 22: Cooling fan 23: Radiator 24: Temperature sensor 25: Three-way valve 26: Hydraulic oil tank 27: Hydraulic pump 28: Oil cooler 30:Storage chamber 31: Bottom wall 32: Ceiling wall 33: Front wall 34: Back wall 35: Right side wall 36: Left side wall 37a, 37b: Support mounts 38:Inflow part 38a, 39a: opening 38b: Cap 39: Outflow section 40: Suction filter (filter) 41: Oil temperature sensor 42: 1st bulkhead 42a, 43a: Upper opening 42b, 43b: Bottom opening 43:Second bulkhead 44:Heat exchange section 50: Controller 51: CPU 52: Memory L1: Cooling channel L2:Heating channel L3: Hydraulic oil flow path

Claims

1. The engine, A cooling fan that generates cooling air; a radiator for exchanging heat between the engine coolant and the cooling air of the cooling fan; A hydraulic oil tank for storing hydraulic oil; A hydraulic pump that pumps the hydraulic oil stored in the hydraulic oil tank; a hydraulic actuator operated by hydraulic oil supplied from the hydraulic pump, The hydraulic oil tank includes: A storage chamber that forms a space for storing hydraulic oil; an inlet portion that allows hydraulic oil returned from the hydraulic actuator to flow into the storage chamber; an outflow portion that causes the hydraulic oil stored in the storage chamber to flow toward the hydraulic pump; A filter connected to the outlet port in the storage chamber and removing dust from the hydraulic oil flowing out through the outlet port. A heating flow path is provided through which the cooling liquid circulates between the engine and the radiator and is inserted into the storage chamber; A work machine, wherein the heating flow path has a heat exchange unit formed in the storage chamber so as to surround the filter.

2. 2. The work machine according to claim 1, A working machine, characterized in that the heat exchange portion of the heating flow passage is formed in a spiral shape so as to surround the filter.

3. 2. The work machine according to claim 1, A work machine, wherein the hydraulic oil tank includes a first partition wall that separates the inlet portion and the filter.

4. 4. The work machine according to claim 3, The hydraulic oil tank includes: An oil temperature sensor that is disposed on the opposite side of the inlet portion across the filter and detects the temperature of the hydraulic oil stored in the storage chamber; a second partition that separates the filter and the oil temperature sensor.

5. 5. The working machine according to claim 4, an upper opening is formed in an upper portion of the first partition wall and an upper portion of the second partition wall, the upper opening penetrating in a thickness direction; A work machine characterized in that a lower end of the upper opening is located above a lower end of the filter and below a full level of hydraulic oil.

6. 6. The working machine according to claim 5, A work machine characterized in that a lower opening penetrating in a thickness direction is formed in a lower portion of the first partition and a lower portion of the second partition.

7. 2. The work machine according to claim 1, A working machine, wherein a cross-sectional shape of the heat exchange portion of the heating flow path is flat.

8. 2. The work machine according to claim 1, an oil temperature sensor that detects the temperature of the hydraulic oil stored in the storage chamber; a controller that adjusts the amount of the cooling liquid circulating through the heating flow path based on the temperature detected by the oil temperature sensor; The working machine, wherein the controller reduces the amount of the cooling liquid circulating through the heating flow passage as the temperature detected by the oil temperature sensor increases.

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