JP7460423B2 - excavator - Google Patents

Description

This disclosure relates to an excavator.

Conventionally, a warm-up operation has been known in which hydraulic oil discharged by a hydraulic pump mounted on an excavator flows out of a relief valve, and the hydraulic oil is warmed by friction when the hydraulic oil passes through the relief valve (Patent Document 1). reference.).

Japanese Patent Application Laid-Open No. 11-117914

However, in the warm-up procedure described above, the hydraulic oil circulates only through a limited portion of the oil passages formed within the valve housing that constitutes the control valve unit, and is therefore unable to warm up other parts of the valve housing.

It would therefore be desirable to provide a shovel that would heat a larger portion of the valve housing during the warm-up procedure.

An excavator according to an embodiment of the present invention includes a lower traveling body, an upper rotating body rotatably mounted on the lower traveling body, a hydraulic pump mounted on the upper rotating body, a hydraulic oil tank mounted on the upper rotating body, a relief valve mounted on the upper rotating body, a control valve unit mounted on the upper rotating body, a first oil passage formed in a valve housing constituting the control valve unit and connecting the hydraulic pump and the hydraulic oil tank, a second oil passage connecting the hydraulic pump and the hydraulic oil tank via the relief valve, a bleed valve for controlling a flow of hydraulic oil in the first oil passage, and a control device for controlling the bleed valve, wherein the control device controls the bleed valve so that the hydraulic oil passes through the bleed valve when the hydraulic oil passes through the relief valve during warm-up, and the hydraulic oil passing through the bleed valve during warm-up is hydraulic oil that leaves the hydraulic pump, passes through the first oil passage, and passes between a plurality of control valves arranged in the valve housing, and is hydraulic oil that leaves the hydraulic pump and does not pass through the relief valve .

The above-mentioned measures provide a shovel that heats a larger portion of the valve housing during warm-up operations.

FIG. 1 is a side view of a shovel according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of the configuration of a drive system mounted on the excavator shown in FIG. 1. FIG. FIG. 2 is a diagram showing an example of the configuration of a hydraulic system installed in the excavator shown in FIG. 1. FIG. It is a flowchart of opening area adjustment processing.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In each drawing, the same components are given the same reference numerals, and redundant explanations may be omitted.

First, the overall configuration of a shovel 100 according to an embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is a side view of the shovel 100.

As shown in FIG. 1, an upper rotating body 3 is rotatably mounted on a lower traveling body 1 of an excavator 100 via a rotating mechanism 2. A boom 4 is attached to the upper rotating body 3. An arm 5 is attached to the tip of the boom 4, and a bucket 6 is attached to the tip of the arm 5 as an end attachment. The boom 4, arm 5, and bucket 6 constitute an excavation attachment as an example of an attachment. The boom 4 is driven by a boom cylinder 7, the arm 5 is driven by an arm cylinder 8, and the bucket 6 is driven by a bucket cylinder 9. A cabin 10 serving as a driver's room is provided on the upper rotating body 3, and a power source such as an engine 11 is mounted on the upper rotating body 3.

A controller 30 is installed inside the cabin 10. The controller 30 functions as a main control unit that controls the drive of the excavator 100. In this embodiment, the controller 30 is configured as a computer including a CPU, RAM, ROM, etc. The various functions of the controller 30 are realized, for example, by the CPU executing a program stored in the ROM.

Next, an example of the configuration of the drive system of the shovel 100 will be described with reference to FIG. 2. FIG. 2 is a block diagram showing an example of the configuration of the drive system of the shovel 100. In FIG. 2, mechanical power transmission lines, hydraulic oil lines, pilot lines, and electrical control lines are indicated by double lines, solid lines, dashed lines, and dashed dotted lines, respectively.

As shown in FIG. 2, the drive system of the excavator 100 mainly includes an engine 11, a regulator 13, a main pump 14, a pilot pump 15, a control valve unit 17, an operating device 26, a discharge pressure sensor 28, an operating pressure sensor 29, a controller 30, a proportional valve 31, and an oil temperature sensor S1.

The engine 11 is the driving source of the excavator 100. In this embodiment, the engine 11 is, for example, a diesel engine that operates to maintain a predetermined rotation speed. In addition, the output shaft of the engine 11 is connected to the input shafts of the main pump 14 and the pilot pump 15.

The main pump 14 is configured to supply hydraulic oil to the control valve unit 17 via a hydraulic oil line. In this embodiment, the main pump 14 is a swash plate type variable displacement hydraulic pump.

The regulator 13 is configured to control the discharge volume of the main pump 14. In this embodiment, the regulator 13 controls the discharge volume (displacement volume) of the main pump 14 by adjusting the swash plate tilt angle of the main pump 14 in response to a control command from the controller 30.

The pilot pump 15 is configured to supply hydraulic oil to various hydraulic control devices such as the operating device 26 and the proportional valve 31 via a pilot line. In this embodiment, the pilot pump 15 is a fixed displacement hydraulic pump. However, the pilot pump 15 may be omitted. In this case, the function of the pilot pump 15 may be realized by the main pump 14. That is, the main pump 14 may have a function of supplying hydraulic oil to the operating device 26 etc. after reducing the pressure of the hydraulic oil to an appropriate level by throttling or the like, in addition to the function of supplying hydraulic oil to the control valve unit 17.

The control valve unit 17 is configured to selectively supply hydraulic oil received from the main pump 14 to one or more hydraulic actuators. In this embodiment, the control valve unit 17 includes a valve housing 17H, and control valves 171-176 and a bleed valve 177 slidably arranged in the valve housing 17H. The control valve unit 17 can selectively supply hydraulic oil discharged by the main pump 14 to one or more hydraulic actuators through the control valves 171-176. The control valves 171-176 are configured to control the flow rate of hydraulic oil flowing from the main pump 14 to the hydraulic actuators, and the flow rate of hydraulic oil flowing from the hydraulic actuators to the hydraulic oil tank TK. The hydraulic actuators include a traveling hydraulic motor 1M, a swing hydraulic motor 2A, a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9. The traveling hydraulic motor 1M includes a left traveling hydraulic motor 1ML and a right traveling hydraulic motor 1MR.

The bleed valve 177 controls the flow rate (hereinafter referred to as "bleed flow rate") of the hydraulic oil that flows into the hydraulic oil tank TK without passing through the hydraulic actuator, out of the hydraulic oil discharged by the main pump 14. The bleed valve 177 may be installed outside the control valve unit 17.

The operating device 26 is a device used by an operator to operate the hydraulic actuators. In this embodiment, the operating device 26 supplies hydraulic oil discharged by the pilot pump 15 to the pilot ports of the control valves corresponding to each hydraulic actuator via a pilot line. The pressure of the hydraulic oil supplied to each pilot port (pilot pressure) is a pressure that corresponds to the operation direction and operation amount of the operating device 26 corresponding to each hydraulic actuator.

However, instead of the hydraulic operation system having such a hydraulic pilot circuit, an electric operation system including an electric operation lever having an electric pilot circuit may be employed. In this case, the lever operation amount of the electric operation lever is input to the controller 30 as an electric signal. Further, a solenoid valve is arranged between the pilot pump 15 and the pilot port of each control valve. The solenoid valve is configured to operate in response to an electrical signal from the controller 30. With this configuration, when manual operation using the electric operation lever is performed, the controller 30 controls the solenoid valves using an electric signal corresponding to the lever operation amount to increase or decrease the pilot pressure, thereby controlling each control valve as a control valve. It can be moved within the unit 17. Incidentally, each control valve may be constituted by an electromagnetic spool valve. In this case, the electromagnetic spool valve operates in response to an electric signal from the controller 30 corresponding to the amount of lever operation of the electric operation lever.

A solenoid valve (not shown) is arranged in a pilot line connecting the pilot pump 15 and each pilot port. The controller 30 can increase or decrease the pilot pressure by controlling the electromagnetic valve according to the operating direction and operating amount of the operating device 26.

The discharge pressure sensor 28 is configured to detect the discharge pressure of the main pump 14. In this embodiment, the discharge pressure sensor 28 outputs the detected value to the controller 30.

The operating pressure sensor 29 is configured to detect the content of the operation of the operating device 26 by the operator. In this embodiment, the operating pressure sensor 29 detects the operating direction and operating amount of the operating device 26 corresponding to each of the hydraulic actuators in the form of pressure (operating pressure), and outputs the detected value to the controller 30. . The operation content of the operating device 26 may be detected using a sensor other than the operating pressure sensor, such as an angle sensor that detects the inclination angle of the operating lever.

The proportional valve 31 is configured to operate according to a control command output by the controller 30. In this embodiment, the proportional valve 31 is a solenoid valve that adjusts the secondary pressure introduced from the pilot pump 15 into the pilot port of the bleed valve 177 in the control valve unit 17 in accordance with the current command output by the controller 30. . The proportional valve 31 operates, for example, so that the larger the supplied current, the larger the secondary pressure introduced into the pilot port of the bleed valve 177.

The oil temperature sensor S1 is configured to be able to detect the temperature of hydraulic oil. In the example shown in FIG. 2, the oil temperature sensor S1 is attached to the oil passage 41, which is a suction oil passage for the main pump 14, and is configured to be able to detect the temperature of the hydraulic oil that the main pump 14 sucks from the hydraulic oil tank TK. ing. The oil temperature sensor S1 is configured to output the detected value to the controller 30. However, the oil temperature sensor S1 may be attached to another oil passage.

Next, referring to FIG. 3, an example of the configuration of a hydraulic system mounted on the excavator 100 will be described. FIG. 3 is a schematic diagram showing an example of the configuration of a hydraulic system mounted on the excavator 100. In FIG. 3, similar to FIG. 2, mechanical power transmission lines, hydraulic oil lines, pilot lines, and electrical control lines are shown by double lines, solid lines, dashed lines, and dashed dotted lines, respectively.

The hydraulic system shown in FIG. 3 circulates hydraulic oil from the main pump 14 driven by the engine 11 to the hydraulic oil tank TK via oil passages 40, 45, and 46, or via oil passages 40, 42, 45, and 46, or via oil passages 40, 43, 44, 45, and 46. The main pump 14 includes a left main pump 14L and a right main pump 14R.

The oil passage 40 includes a left oil passage 40L and a right oil passage 40R. The left oil passage 40L is a hydraulic oil line connecting each of the control valves 171, 173, 175L, and 176L arranged in the control valve unit 17 to the left main pump 14L. The right oil passage 40R is a hydraulic oil line connecting each of the control valves 172, 174, 175R, and 176R arranged in the control valve unit 17 to the right main pump 14R. In FIG. 3, for clarity, the oil passage 40 is shown not to overlap with each of the control valves 171 to 176, but in reality, the oil passage 40 is configured so that the hydraulic oil flowing through the oil passage 40 contacts the center of each of the control valves 171 to 176. In other words, the oil passage 40 is configured to intersect with the spool holes in which each of the control valves 171 to 176 is housed. The oil passage 40 is configured so that the flow of hydraulic oil through the oil passage 40 is not restricted by the spool portions when the spool portions of the control valves 171-176 are in the neutral valve position and when at least one of the spool portions has moved from the neutral valve position. However, the oil passage 40 may be configured so that the hydraulic oil flowing through the oil passage 40 does not come into contact with each of the control valves 171-176, that is, to bypass each of the control valves 171-176 as shown in FIG. 3.

Specifically, the left oil passage 40L is a hydraulic oil line that connects the control valves 171, 173, 175L, and 176L arranged in the control valve unit 17 in parallel between the left main pump 14L and the hydraulic oil tank TK. The right oil passage 40R is a hydraulic oil line that connects the control valves 172, 174, 175R, and 176R arranged in the control valve unit 17 in parallel between the right main pump 14R and the hydraulic oil tank TK.

The oil passage 41 is a suction oil passage for the main pump 14, and includes a left oil passage 41L that is a suction oil passage for the left main pump 14L, and a right oil passage 41R that is a suction oil passage for the right main pump 14R. In the example shown in FIG. 3, the oil temperature sensor S1 is attached to the right oil passage 41R. However, the oil temperature sensor S1 may be attached to the left oil passage 41L, or may be attached to both the left oil passage 41L and the right oil passage 41R. In addition, the oil temperature sensor S1 is not connected to the oil passage 41 located upstream of the main pump 14, but is located other than the oil passage 41 located downstream of the main pump 14, such as the oil passage 40, the oil passage 42, or the oil passage 43. may be attached to another oil passage. Further, the oil temperature sensor S1 may be attached to a hydraulic oil tank.

The oil passage 42 is a return oil passage for returning hydraulic oil flowing out from the hydraulic actuator to the hydraulic oil tank TK, and includes a left oil passage 42L and a right oil passage 42R. The left oil passage 42L is a hydraulic oil line that connects the CT ports of the control valves 171, 175L, and 176L to the oil passage 45. The right oil passage 42R is a hydraulic oil line that connects the CT ports of the control valves 172, 174, 175R, and 176R to the oil passage 45.

The oil passage 43 includes a central oil passage 43C, a left oil passage 43L, and a right oil passage 43R. The left oil passage 43L is a hydraulic oil line that connects the left oil passage 42L and the central oil passage 43C, and the right oil passage 43R is a hydraulic oil line that connects the right oil passage 42R and the central oil passage 43C. A relief valve 50 is arranged in the central oil passage 43C.

Oil passage 44 is a hydraulic oil line that connects central oil passage 43C and oil passage 45, and includes left oil passage 44L and right oil passage 44R. Hydraulic oil that passes through relief valve 50 arranged in central oil passage 43C flows into both left oil passage 44L and right oil passage 44R.

The oil passage 45 is a hydraulic oil line that connects the oil passage 46 with each of the oil passage 40 , the oil passage 42 , and the oil passage 44 . With this configuration, the hydraulic oil flowing through the oil passage 40 flows into the oil passage 46 through the oil passage 45 . The same applies to the oil passage 42 and the oil passage 44.

The oil passage 46 is a hydraulic oil line connecting the oil passage 45 and the hydraulic oil tank TK, and includes a left oil passage 46L and a right oil passage 46R. A left check valve 52L and an oil cooler 53 are arranged in the left oil passage 46L, and a right check valve 52R is arranged in the right oil passage 46R. The left check valve 52L and the right check valve 52R are spring-type check valves configured to stop the flow (backflow) of hydraulic oil from the hydraulic oil tank TK to the oil passage 45. In addition, the left check valve 52L and the right check valve 52R are configured so that the back pressure generated by the left check valve 52L is smaller than the back pressure generated by the right check valve 52R. Therefore, the hydraulic oil flowing through the oil passage 45 basically flows into the left oil passage 46L, and flows into the right oil passage 46R when the pressure of the hydraulic oil in the left oil passage 46L exceeds a predetermined value.

The oil cooler 53 is a device for cooling the hydraulic oil flowing through the left oil passage 46L. In the example shown in FIG. 3, the oil cooler 53 is an air-cooled oil cooler, and the hydraulic oil flowing through a part of the left oil passage 46L formed in the oil cooler 53 is cooled by a fan driven by the engine 11. be done. However, the oil passage 46 may be configured so that the hydraulic oil flowing through the oil passage 45 does not pass through the oil cooler 53 when warm-up work is being performed.

The control valve 171 supplies hydraulic oil discharged by the left main pump 14L to the left travel hydraulic motor 1ML, and discharges the hydraulic oil discharged by the left travel hydraulic motor 1ML to the hydraulic oil tank TK. This is a spool valve that switches the flow of water.

The control valve 172 supplies hydraulic oil discharged by the right main pump 14R to the right hydraulic motor 1MR, and discharges hydraulic oil discharged by the right hydraulic motor 1MR to the hydraulic oil tank TK. This is a spool valve that switches the flow of water.

The control valve 173 controls the flow of hydraulic oil in order to supply the hydraulic oil discharged by the left main pump 14L to the swing hydraulic motor 2A, and to discharge the hydraulic oil discharged by the swing hydraulic motor 2A to the hydraulic oil tank TK. It is a spool valve that switches the

The control valve 174 is a spool valve that supplies the hydraulic oil discharged by the right main pump 14R to the bucket cylinder 9 and discharges the hydraulic oil in the bucket cylinder 9 to the hydraulic oil tank TK.

The control valve 175 is a spool valve that switches the flow of hydraulic oil in order to supply the hydraulic oil discharged by the main pump 14 to the boom cylinder 7 and to discharge the hydraulic oil in the boom cylinder 7 to the hydraulic oil tank TK. . In the example shown in FIG. 3, the control valve 175 includes a control valve 175L and a control valve 175R. The control valve 175L is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the left main pump 14L to the bottom side oil chamber of the boom cylinder 7. The control valve 175R is a spool valve that switches the flow of hydraulic oil in order to supply the hydraulic oil discharged by the right main pump 14R to the boom cylinder 7 and to discharge the hydraulic oil in the boom cylinder 7 to the hydraulic oil tank TK. be.

The control valve 176 is a spool valve that switches the flow of hydraulic oil in order to supply the hydraulic oil discharged by the main pump 14 to the arm cylinder 8 and to discharge the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank TK. . In the example shown in FIG. 3, the control valve 176 includes a control valve 176L and a control valve 176R. The control valve 176L is a spool valve that switches the flow of hydraulic oil in order to supply the hydraulic oil discharged by the left main pump 14L to the arm cylinder 8 and to discharge the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank TK. be. The control valve 176R is a spool valve that switches the flow of hydraulic oil in order to supply the hydraulic oil discharged by the right main pump 14R to the arm cylinder 8 and to discharge the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank TK. be.

The bleed valve 177 is a spool valve that controls the bleed flow rate of the hydraulic fluid discharged by the main pump 14. In the example shown in FIG. 3, the bleed valve 177 includes a left bleed valve 177L and a right bleed valve 177R. The left bleed valve 177L is a spool valve that controls the bleed flow rate of the hydraulic oil discharged by the left main pump 14L. The right bleed valve 177R is a spool valve that controls the bleed flow rate of the hydraulic oil discharged by the right main pump 14R.

The bleed valve 177 is configured to be movable, for example, between a first valve position with a minimum opening area (0% opening) and a second valve position with a maximum opening area (100% opening). In the example shown in FIG. 3, the bleed valve 177 is configured to be able to move steplessly between the first valve position and the second valve position.

Figure 3 shows the extent of the valve housing 17H that constitutes the control valve unit 17 with a dotted line. That is, Figure 3 shows that the control valves 171-176, oil passage 40, oil passage 42-oil passage 45, and relief valve 50 are arranged within the valve housing 17H. However, the extent of the valve housing 17H shown in Figure 3 does not represent the actual shape of the valve housing 17H. The valve housing 17H is typically a casting having a substantially rectangular parallelepiped shape. In the example shown in Figure 3, the valve housing 17H is a one-piece casting. Furthermore, the oil passages within the valve housing 17H shown in Figure 3 only represent the connection relationships and do not represent the actual route of the oil passages.

The regulator 13 is configured to control the discharge volume (displacement volume) of the main pump 14 by adjusting the swash plate tilt angle of the main pump 14. In the example shown in FIG. 3, the regulator 13 includes a left regulator 13L and a right regulator 13R. For example, the controller 30 adjusts the swash plate tilt angle of the left main pump 14L with the left regulator 13L in response to an increase in the discharge pressure of the left main pump 14L to reduce the discharge volume of the left main pump 14L. The same is true for the discharge volume of the right main pump. This is to prevent the absorption power (absorption horsepower) of the main pump 14, which is expressed as the product of the discharge pressure and the discharge volume, from exceeding the output power (output horsepower) of the engine 11.

The left operating lever 26L is one of the operating devices 26, and is used to operate the swing hydraulic motor 2A and the arm cylinder 8. Specifically, the operator can extend and retract the arm cylinder 8 by operating the left operating lever 26L in the forward and backward directions, and can rotate the swing hydraulic motor 2A by operating the left operating lever 26L in the left and right directions.

When the left operating lever 26L is operated in the front-rear direction, the pilot pressure applied to the pilot port of the control valve 176 is applied to the pilot port of the control valve 176 using hydraulic oil discharged by the pilot pump 15. Specifically, when the left operating lever 26L is operated in the arm closing direction (rearward), hydraulic oil is introduced into the right pilot port of the control valve 176L, and hydraulic oil is introduced into the left pilot port of the control valve 176R. be introduced. Furthermore, when the left operating lever 26L is operated in the arm opening direction (forward), hydraulic oil is introduced into the left pilot port of the control valve 176L, and hydraulic oil is introduced into the right pilot port of the control valve 176R. let The same applies to the case where the left operating lever 26L is operated in the left-right direction to rotate the turning hydraulic motor 2A.

The right operating lever 26R is one of the operating devices 26, and is used to operate the boom cylinder 7 and the bucket cylinder 9. Specifically, the operator can extend and retract the boom cylinder 7 by operating the right operating lever 26R in the forward and backward directions, and can extend and retract the bucket cylinder 9 by operating the right operating lever 26R in the left and right directions.

When the right operating lever 26R is operated in the front-rear direction, the pilot pressure applied to the pilot port of the control valve 175 is applied to the pilot port of the control valve 175 using hydraulic oil discharged by the pilot pump 15. Specifically, when the right operating lever 26R is operated in the boom raising direction (rearward), hydraulic oil is introduced into the right pilot port of the control valve 175L, and hydraulic oil is introduced into the left pilot port of the control valve 175R. be introduced. Further, when the right operating lever 26R is operated in the boom lowering direction (forward), hydraulic oil is introduced into the right pilot port of the control valve 175R. The same applies when the right operating lever 26R is operated in the left-right direction to extend or contract the bucket cylinder 9.

The discharge pressure sensor 28 detects the discharge pressure of the main pump 14 and outputs the detected value to the controller 30. In the example shown in FIG. 3, the discharge pressure sensor 28 includes a left discharge pressure sensor 28L and a right discharge pressure sensor 28R. The left discharge pressure sensor 28L detects the discharge pressure of the left main pump 14L and outputs the detected value to the controller 30. The right discharge pressure sensor 28R detects the discharge pressure of the right main pump 14R and outputs the detected value to the controller 30.

The operating pressure sensor 29 detects the operation of the operator on the operating device 26 in the form of pressure, and outputs the detected value to the controller 30. In the example shown in FIG. 3, the operating pressure sensor 29 includes a left operating pressure sensor 29L and a right operating pressure sensor 29R. The left operating pressure sensor 29L detects the operation of the operator on the left operating lever 26L in the form of pressure, and outputs the detected value to the controller 30. The right operating pressure sensor 29R detects the operation of the operator on the right operating lever 26R in the form of pressure, and outputs the detected value to the controller 30. The operation content is, for example, the lever operation direction and lever operation amount (lever operation angle), etc.

The traveling operating device (not shown) is an operating device for causing the lower traveling body 1 to travel. The travel operating device typically includes a left travel lever, a right travel lever, a left travel pedal, and a right travel pedal. Similar to the left operating lever 26L and the right operating lever 26R, the traveling operating device uses hydraulic oil discharged by the pilot pump 15 to apply pilot pressure to the traveling hydraulic motor 1M according to the amount of lever operation or pedal operation. act on either the left or right pilot port of the control valve. The content of the operator's operation on the travel operating device is detected in the form of pressure by the corresponding operating pressure sensor, and the detected value is output to the controller 30.

The controller 30 is configured to receive outputs from the control pressure sensor 19, the discharge pressure sensor 28, the operating pressure sensor 29, etc., and output a control command to the regulator 13 as necessary to change the discharge volume of the main pump 14. The controller 30 is also configured to output a current command to the proportional valve 31 as necessary to change the opening area of the bleed valve 177.

The proportional valve 31 is configured to adjust the secondary pressure introduced from the pilot pump 15 to the pilot port of the bleed valve 177 in accordance with the current command output by the controller 30. In the example shown in FIG. 3, the proportional valve 31 includes a left proportional valve 31L and a right proportional valve 31R. The left proportional valve 31L can adjust the secondary pressure so that the left bleed valve 177L can be stopped at any position between the first valve position and the second valve position. The right proportional valve 31R can adjust the secondary pressure so that the right bleed valve 177R can be stopped at any position between the first valve position and the second valve position.

Next, negative control control employed in the hydraulic system shown in FIG. 3 will be explained. In the oil passage 40, a throttle 18 is arranged between a bleed valve 177, which is the most downstream spool valve, and a hydraulic oil tank TK. The flow of hydraulic oil passing through the bleed valve 177 and reaching the hydraulic oil tank TK is restricted by the throttle 18. The throttle 18 generates a control pressure for controlling the regulator 13, that is, a control pressure for controlling the discharge amount of the main pump 14. The control pressure sensor 19 is a sensor for detecting control pressure, and outputs the detected value to the controller 30.

In the example shown in FIG. 3, the orifices 18 are fixed orifices whose opening area does not change, and include a left orifice 18L arranged between the left bleed valve 177L and the hydraulic oil tank TK in the left oil passage 40L, and a right orifice 18R arranged between the right bleed valve 177R and the hydraulic oil tank TK in the right oil passage 40R. The control pressure sensor 19 includes a left control pressure sensor 19L that detects the control pressure generated by the left orifice 18L to control the left regulator 13L, and a right control pressure sensor 19R that detects the control pressure generated by the right orifice 18R to control the right regulator 13R.

The controller 30 controls the discharge amount (displaced volume) of the main pump 14 by adjusting the swash plate tilt angle of the main pump 14 according to the control pressure. Hereinafter, the relationship between the control pressure and the discharge amount of the main pump 14 will be referred to as a "negative control characteristic." Control of the ejection amount based on the negative control characteristic may be realized, for example, by using a reference table stored in a ROM or the like, or by executing predetermined calculations in real time. In the example shown in FIG. 3, the controller 30 refers to a reference table representing predetermined negative control characteristics, and decreases the discharge amount of the main pump 14 as the control pressure increases, and decreases the discharge amount of the main pump 14 as the control pressure decreases. increase.

Specifically, as shown in FIG. 3, when none of the operating devices 26 are operated and no hydraulic actuators are operating, that is, when the hydraulic system is in a standby state, the left main pump 14L is activated. The discharged hydraulic oil passes through the left bleed valve 177L and reaches the left throttle 18L. If the flow rate of the hydraulic oil reaching the left throttle 18L is equal to or higher than a predetermined flow rate, the control pressure generated upstream of the left throttle 18L reaches the predetermined pressure. When the control pressure reaches a predetermined pressure, the controller 30 reduces the discharge amount of the left main pump 14L to a predetermined allowable minimum discharge amount, and reduces the pressure loss (pumping) when the discharged hydraulic oil passes through the left oil passage 40L. loss). This predetermined minimum allowable discharge amount in the standby state is referred to as the "standby flow rate." The controller 30 similarly controls the discharge amount of the right main pump 14R.

On the other hand, when any of the hydraulic actuators is operated, the hydraulic oil discharged by the left main pump 14L flows into the hydraulic actuator to be operated through the control valve corresponding to the hydraulic actuator to be operated. Then, the controller 30 outputs a control command to the left proportional valve 31L, and reduces the opening area of the left bleed valve 177L according to the amount of movement of the control valve corresponding to the hydraulic actuator to be operated. The amount of movement of the control valve corresponds to the control pressure acting on the pilot port of the control valve. When a plurality of control valves are moved simultaneously, the controller 30 reduces the opening area of the left bleed valve 177L according to the total movement amount of the plurality of control valves. The controller 30 is typically configured to make the opening area of the left bleed valve 177L smaller as the total amount of movement of the control valves becomes larger. In this case, the flow rate of the hydraulic oil passing through the left bleed valve 177L and reaching the left throttle 18L decreases, and the control pressure generated upstream of the left throttle 18L decreases. As a result, the controller 30 increases the discharge amount of the left main pump 14L, supplies sufficient hydraulic oil to the hydraulic actuator to be operated, and ensures the drive of the hydraulic actuator to be operated. The controller 30 similarly controls the discharge amount of the right main pump 14R. Note that, hereinafter, the flow rate of hydraulic oil flowing into the hydraulic actuator will be referred to as "actuator flow rate." In this case, the flow rate of the hydraulic oil discharged by the left main pump 14L corresponds to the sum of the actuator flow rate for the left oil passage 40L and the bleed flow rate for the left oil passage 40L. The same applies to the flow rate of hydraulic oil discharged by the right main pump 14R.

With the above-mentioned configuration, the hydraulic system shown in FIG. 3 can reliably supply sufficient hydraulic oil from the main pump 14 to the hydraulic actuator to be operated when the hydraulic actuator is operated. Furthermore, in the standby state, the hydraulic system shown in FIG. 3 can suppress the wasteful consumption of hydraulic energy. This is because the bleed flow rate can be reduced to the standby flow rate.

The relief valve 50 is configured to release hydraulic oil into the hydraulic oil tank TK when the pressure of the hydraulic oil in the oil passage 40 exceeds a predetermined relief pressure. This is because an excessive increase in the pressure of the hydraulic oil in the oil passage 40 may cause damage to hydraulic equipment or structures constituting the hydraulic system. In the example shown in FIG. 3, the relief valve 50 is arranged in the oil passage 43. The oil passage 43 is a hydraulic oil line that connects the oil passage 40 and the hydraulic oil tank TK via oil passages 44 to 46. Further, a check valve 51 is arranged in the oil passage 43. In the example shown in FIG. 3, the relief valve 50 has a fixed relief pressure set in a fixed manner, but may be a variable relief valve whose relief pressure is variable.

The check valve 51 is configured to stop the flow (backflow) of hydraulic oil from the hydraulic oil tank TK (central oil passage 43C) to the oil passage 40. In the example shown in FIG. 3, the check valve 51 includes a left check valve 51L that stops the flow (reverse flow) of hydraulic oil from the hydraulic oil tank TK (center oil passage 43C) to the left oil passage 40L, and a left check valve 51L that stops the flow (backflow) of hydraulic oil from the hydraulic oil tank TK (center oil passage 43C) to the left oil passage 40L; It includes a right check valve 51R that stops the flow (reverse flow) of hydraulic oil from the oil passage 43C) to the right oil passage 40R.

In the example shown in FIG. 3, the relief valve 50 is arranged in the central oil passage 43C, the left check valve 51L is arranged in the left oil passage 43L, and the right check valve 51R is arranged in the right oil passage 43R.

In this way, the hydraulic system shown in FIG. 3 is configured so that the hydraulic oil in each of the left oil passage 40L and the right oil passage 40R can be released to the hydraulic oil tank TK with one relief valve 50. However, the hydraulic system shown in FIG. 3 may also have a left relief valve for releasing the hydraulic oil in the left oil passage 40L to the hydraulic oil tank TK and a right relief valve for releasing the hydraulic oil in the right oil passage 40R to the hydraulic oil tank TK separately. In this case, the left relief valve is disposed in the oil passage connecting the left oil passage 40L and the hydraulic oil tank TK, and the right relief valve is disposed in the oil passage connecting the right oil passage 40R and the hydraulic oil tank TK.

Next, a warm-up work performed on the excavator 100 will be described. The warm-up operation is an operation for increasing the temperature of the hydraulic oil circulating in the control valve unit 17. Typically, the operator of excavator 100 performs this warm-up work when starting excavator 100 in a cold region. The temperature of the hydraulic oil is increased, for example, by releasing the hydraulic oil from the relief valve 50. Typically, the operator closes the bucket 6 by completely tilting the right operating lever 26R to the left, and then continues to fully tilt the right operating lever 26R to the left even after the bucket 6 is completely closed. . That is, the operator continues to supply hydraulic oil to the bottom side oil chamber of the bucket cylinder 9 even after the bucket cylinder 9 is extended to the maximum extent. In this case, the hydraulic oil discharged by the right main pump 14R flows into the bottom oil chamber of the bucket cylinder 9 via the control valve 174 until the bucket 6 is completely closed. Then, the hydraulic oil cannot flow into the bottom side oil chamber of the bucket cylinder 9, and the pressure of the hydraulic oil in the right oil passage 40R increases. Note that when the right operating lever 26R is completely tilted to the left, the right bleed valve 177R is positioned at the first valve position with the minimum opening area (opening degree 0%). When the pressure of the hydraulic oil in the right oil passage 40R exceeds the relief pressure of the relief valve 50, the relief valve 50 opens, and the hydraulic oil discharged by the right main pump 14R is transferred to the right oil passage 43R, the right check valve 51R, and the relief valve 50. It is discharged into the hydraulic oil tank TK through the valve 50, the central oil passage 43C, the oil passage 44, the oil passage 45, and the oil passage 46. As a result, the hydraulic oil discharged by the right main pump 14R is heated by friction when passing through the relief valve 50. If this discharge continues, the temperature of the hydraulic oil in the hydraulic oil tank TK increases. In the example shown in FIG. 3, when the relief valve 50 is opened after the warm-up operation is performed, the controller 30 makes the discharge amount of the left main pump 14L almost zero. This is to allow more low-temperature hydraulic oil to pass through the relief valve 50. However, the controller 30 may maintain the discharge amount of the left main pump 14L at the minimum allowable discharge amount even if the relief valve 50 is opened due to warm-up work.

The operator can judge whether the temperature of the hydraulic oil has reached a desired temperature while viewing information regarding the temperature of the hydraulic oil displayed on a display device installed in the cabin 10. The controller 30 is configured to display information regarding the temperature of the hydraulic oil acquired from the oil temperature sensor S1 on a display device. When the operator determines that the temperature of the hydraulic oil has reached the desired temperature, the operator returns the right operating lever 26R to the neutral position and stops releasing the hydraulic oil through the relief valve 50, thereby completing the warm-up work. .

In the above example, the operator performs the warm-up operation by continuing the operation of closing the bucket 6, but the operator may also perform the warm-up operation by continuing the operation of opening the bucket 6, or by continuing the operation of raising the boom 4. Alternatively, the operator may perform the warm-up operation by continuing the operation of lowering the boom 4, or by continuing the operation of opening the arm 5, or by continuing the operation of closing the arm 5.

In a configuration in which all of the hydraulic oil that has passed through the relief valve 50 during warm-up work is discharged into the hydraulic oil tank TK through the oil passages 44 to 46, the high-temperature oil that has passed through the relief valve 50 is The hydraulic oil is discharged into the hydraulic oil tank TK while locally heating a portion of the valve housing 17H of the control valve unit 17. This is because the oil passage 44 is formed at a corner of the valve housing 17H having a substantially rectangular parallelepiped shape. In this case, when the temperature of the hydraulic oil in the hydraulic oil tank TK rises to the desired temperature, the portion of the control valve unit 17 close to the oil passage 44 is warmed, but the portion far from the oil passage 44 remains cold. There is even.

If the control valve unit 17 is in such a state and the normal operation of the excavator 100 is started even though the hydraulic oil has sufficiently warmed up, the movement of the excavator 100 may become unstable. For example, when the operator tilts the right control lever 26R backward in order to raise the boom 4, the spool portion that constitutes the control valve 175 sticks to the spool hole formed in the valve housing 17H of the control valve unit 17. There is a risk that it will happen. This is because the spool part and spool hole do not thermally expand because they are not in contact with hydraulic oil during warm-up work, and the spool part that comes into contact with high-temperature hydraulic oil immediately after normal operation starts. This is because the spool hole thermally expands faster than the spool hole that is in contact with high-temperature hydraulic oil. In this case, even if the right operating lever 26R is returned to the neutral position, the boom 4 may continue to rise because the spool portion does not return to the neutral valve position.

This problem is thought to be caused by the difference between the heat capacity of the spool portion and the heat capacity of the valve housing 17H. That is, this problem is considered to be caused by the thermal expansion of the spool portion proceeding faster than the thermal expansion of the spool hole because the thermal capacity of the spool portion is significantly smaller than that of the valve housing 17H.

Therefore, the excavator 100 according to the embodiment of the present invention prevents the control valve from being locally heated during warm-up work, and also warms a wider portion of the control valve unit 17. It is configured so that it can be done. In other words, the shovel 100 is configured to prevent the occurrence of problems such as unstable movement of the shovel 100. Specifically, the shovel 100 prevents only a portion of the spool from being locally heated during warm-up work, and also prevents the entire spool hole from being heated evenly. By doing so, it is possible to suppress the occurrence of problems such as unstable movement of the shovel 100.

If only a portion of the valve housing 17H is locally heated, only a portion of the valve housing 17H may locally expand thermally, causing distortion in the spool hole formed in the valve housing 17H. This is because there is. Additionally, if only a portion of the control valve is locally heated, only that portion of the control valve will locally expand thermally, causing distortion in the spool that forms part of the control valve. This is because there is a risk. If distortion occurs in at least one of the spool hole and the spool portion, the spool hole and the spool portion will come into contact and smooth movement of the spool portion within the spool hole will be hindered.

More specifically, when the warm-up operation is being performed, the controller 30 causes hydraulic oil to flow into the oil passage 40 so that a wider portion of the valve housing 17H is warmed up. With this configuration, the controller 30 can prevent the spool hole from coming into contact with the spool portion, which would hinder smooth movement of the spool portion within the spool hole.

Here, with reference to FIG. 4, a process in which the controller 30 adjusts the opening area of the bleed valve 177 in order to cause hydraulic oil to flow into the oil passage 40 (hereinafter referred to as "opening area adjustment process") will be described. . FIG. 4 is a flowchart of the opening area adjustment process. When the controller 30 determines that the warm-up work is being performed, the controller 30 repeatedly executes this opening area adjustment process at a predetermined control cycle. In this embodiment, the controller 30 determines whether or not warm-up work is being performed based on the outputs of the operating pressure sensor 29, oil temperature sensor S1, and the like. Specifically, when the controller 30 detects that the right operating lever 26R is continuously operated in the bucket closing direction for a predetermined period of time, and also detects that the temperature of the hydraulic oil is below the predetermined temperature. It is determined that warm-up work is being performed. Note that the controller 30 can detect whether the right operating lever 26R is operated in the bucket closing direction based on the output of the operating pressure sensor 29. When an electric operation lever is adopted, the controller 30 can determine whether the right operation lever 26R is operated in the bucket closing direction based on the electric signal output by the operation device 26, and can therefore determine whether or not the right operation lever 26R is operated in the bucket closing direction. It can be determined whether machine work is being performed or not.

First, the controller 30 determines whether the temperature of the hydraulic oil is below a predetermined temperature Tth (step ST1). That is, the controller 30 determines whether a warm-up operation is necessary based on the temperature of the hydraulic oil. In this embodiment, the controller 30 derives the current temperature of the hydraulic oil from the value output by the oil temperature sensor S1 and compares this temperature with the predetermined temperature Tth.

If it is determined that the temperature of the hydraulic oil is equal to or higher than the predetermined temperature Tth (NO in step ST1), the controller 30 ends the current opening area adjustment process. This is because the controller 30 can determine that the valve housing 17H is not in a cold state and there is no need to warm the valve housing 17H.

On the other hand, when it is determined that the temperature of the hydraulic oil is below the predetermined temperature Tth (YES in step ST1), the controller 30 determines whether or not the hydraulic oil is passing through the relief valve 50 (step ST2). In this embodiment, the operator of the excavator 100 continues to close the bucket 6 to perform warm-up work. Therefore, the controller 30 determines whether or not the discharge pressure of the right main pump 14R is equal to or higher than the relief pressure of the relief valve 50. The discharge pressure of the right main pump 14R is derived from the output of the right discharge pressure sensor 28R. Then, when the controller 30 determines that the discharge pressure of the right main pump 14R is equal to or higher than the relief pressure of the relief valve 50, it determines that the hydraulic oil is passing through the relief valve 50, and when the controller 30 determines that the discharge pressure of the right main pump 14R is lower than the relief pressure of the relief valve 50, it determines that the hydraulic oil is not passing through the relief valve 50. Instead of determining whether the discharge pressure of the right main pump 14R is equal to or greater than the relief pressure of the relief valve 50, the controller 30 may determine whether the discharge pressure of the right main pump 14R is equal to or greater than the cracking pressure of the relief valve 50.

If it is determined that the hydraulic oil has not passed through the relief valve 50 (NO in step ST2), the controller 30 ends the current opening area adjustment process. This is because the controller 30 can determine that the hydraulic oil has not yet passed through the relief valve 50 and is not yet warm.

On the other hand, if it is determined that the hydraulic oil is passing through the relief valve 50 (YES in step ST2), the controller 30 starts adjusting the opening area of the bleed valve 177 (step ST3). If adjustment of the opening area of the bleed valve 177 has already started, the controller 30 continues the adjustment. In this embodiment, the operator of the excavator 100 performs the warming-up work by continuing the operation of closing the bucket 6. The right bleed valve 177R is positioned at the first valve position with the minimum opening area (opening degree 0%). Therefore, the controller 30 moves the right bleed valve 177R to the second valve position. The hydraulic oil in the right oil passage 40R passes through the right bleed valve 177R and is discharged to the hydraulic oil tank TK, so that the hydraulic oil discharged by the right main pump 14R flows through the right oil passage 40R. This is to do so. At this time, the controller 30 adjusts the opening area of the right bleed valve 177R so that the discharge pressure of the right main pump 14R does not fall below a predetermined pressure. The predetermined pressure is, for example, a relief pressure or a cracking pressure. Specifically, the controller 30 reduces the opening area of the right bleed valve 177R as the discharge pressure of the right main pump 14R approaches a predetermined pressure. This is to maintain a state in which hydraulic oil passes through the relief valve 50.

The controller 30 may also increase the discharge amount of the left main pump 14L to a predetermined value (for example, the minimum allowable discharge amount) when the temperature of the hydraulic oil reaches a predetermined value (a temperature lower than a desired temperature). good. Note that the left bleed valve 177L is positioned at the second valve position with the maximum opening area (100% opening).

The controller 30 continues to adjust the opening area of the bleed valve 177 while determining that the warm-up work is being performed, and adjusts the opening area of the bleed valve 177 when determining that the warm-up work is not being performed. The adjustment of the area is stopped and the bleed valve 177 is returned to the second valve position with the maximum opening area (opening degree 100%). In this embodiment, the controller 30 continues to adjust the opening area of the right bleed valve 177R while it is determined that the warm-up work is being performed, and when it is determined that the warm-up work is not being performed. , the adjustment of the opening area of the right bleed valve 177R is stopped and the right bleed valve 177R is returned to the second valve position of the maximum opening area (opening degree 100%).

Through this opening area adjustment process, the controller 30 causes the hydraulic oil that has been heated by passing through the relief valve 50 and returned to the hydraulic oil tank TK to flow into the oil passage 40 while the warm-up work is being performed. be able to. Note that the hydraulic oil heated by passing through the relief valve 50 and returned to the hydraulic oil tank TK mixes with the unheated hydraulic oil in the hydraulic oil tank TK when it returns to the hydraulic oil tank TK. to warm up the unheated hydraulic oil. The right main pump 14R sucks the hydraulic oil in the hydraulic oil tank TK heated in this way and discharges it toward the oil path 40. Therefore, the controller 30 can warm the portion of the valve housing 17H that includes the oil passage 40 using the thus-warmed hydraulic oil. That is, the controller 30 can warm a wider portion of the valve housing 17H than when the hydraulic oil is not allowed to flow into the oil passage 40 during the warm-up operation. As a result, the controller 30 can prevent the spool portion forming the control valve from sticking to the spool hole formed in the valve housing 17H when normal operation is started after the warm-up work.

As described above, the excavator 100 according to an embodiment of the present invention has a lower running body 1, an upper rotating body 3 rotatably mounted on the lower running body 1, a main pump 14 as a hydraulic pump mounted on the upper rotating body 3, a hydraulic oil tank TK mounted on the upper rotating body 3, a relief valve 50 mounted on the upper rotating body 3, a control valve unit 17 mounted on the upper rotating body 3, an oil passage 40 as a first oil passage formed within a valve housing 17H constituting the control valve unit 17 and connecting the main pump 14 and the hydraulic oil tank TK, an oil passage 43 as a second oil passage connecting the main pump 14 and the hydraulic oil tank TK via the relief valve 50, a bleed valve 177 that controls the flow of hydraulic oil in the oil passage 40, and a controller 30 as a control device that controls the bleed valve 177. The controller 30 is configured to control the bleed valve 177 so that hydraulic oil passes through the bleed valve 177 when hydraulic oil passes through the relief valve 50 during warm-up. With this configuration, the excavator 100 can warm a wider portion of the valve housing 17H when warm-up work is being performed.

In the example shown in FIG. 3, the excavator 100 allows the hydraulic oil to be heated through an oil passage 40 formed to intersect with the spool hole so that the spool portion and the spool hole are in contact with the hydraulic oil to be heated. By flowing the hydraulic oil, a wide portion of the valve housing 17H can be warmed. However, the excavator 100 can increase the temperature of the valve housing 17H by flowing the hydraulic oil to be heated through the oil passages 40 formed near the spool portion and the spool hole (formed so as not to intersect with the spool hole). It may be configured to be able to heat a wide area. In addition, since the valve housing 17H is typically a metal casting, it has good thermal conductivity. Therefore, regardless of whether or not the oil passage 40 intersects with the spool hole, the heated hydraulic oil can appropriately warm the control valves 171 to 176 and their surroundings.

The excavator 100 desirably includes an oil passage 41 as a suction oil passage arranged on the suction side of the main pump 14 and an oil temperature sensor S1 attached to the oil passage 41. In this case, the controller 30 closes the bleed valve 177 to the hydraulic oil when the value output by the oil temperature sensor S1 is below a predetermined value, and when the hydraulic oil is passing through the relief valve 50 during warm-up. The bleed valve 177 is controlled so that the The controller 30 starts an opening area adjustment process for adjusting the opening area of the bleed valve 177, for example. This is because the controller 30 can determine that the valve housing 17H is cold when the value output by the oil temperature sensor S1 is less than or equal to a predetermined value when the excavator 100 is started. However, the controller 30 operates the bleed valve when the value output by the temperature sensor attached to the valve housing 17H is below a predetermined value, and when hydraulic oil is passing through the relief valve 50 during warm-up. The opening area adjustment process may be started so that hydraulic oil passes through 177. In this case, the oil temperature sensor S1 may be omitted. This configuration allows the controller 30 to heat the valve housing 17H only when it is necessary to heat the valve housing 17H. That is, if the temperature of the valve housing 17H is sufficiently high, the controller 30 does not control the bleed valve 177 even when the hydraulic oil is passing through the relief valve 50. Therefore, the controller 30 can prevent the opening area of the bleed valve 177 from being adjusted when there is no need to warm the valve housing 17H.

Excavator 100 desirably includes a discharge pressure sensor 28 that detects the discharge pressure of main pump 14 . In this case, when the value output by the discharge pressure sensor 28 is greater than or equal to a predetermined value, the controller 30 determines that the hydraulic oil is passing through the relief valve 50 and controls the bleed valve so that the hydraulic oil passes through the bleed valve 177. 177. With this configuration, the controller 30 can adjust the opening area of the bleed valve 177 while confirming that the hydraulic oil is passing through the relief valve 50. That is, the controller 30 can cause the heated hydraulic oil to flow into the oil passage 40 (via the hydraulic oil tank TK) while continuing to heat the hydraulic oil by passing the hydraulic oil through the relief valve 50. . Therefore, the controller 30 can prevent the hydraulic oil from being discharged into the hydraulic oil tank TK through the bleed valve 177 in a state where the heating of the hydraulic oil due to the hydraulic oil passing through the relief valve 50 is interrupted. However, the controller 30 may cause the bleed valve 177 to function as a relief valve. In this case, the hydraulic oil discharged by the main pump 14 is discharged into the hydraulic oil tank TK through the bleed valve 177 at a pressure lower than the relief pressure of the relief valve 50. The hydraulic oil is heated by friction as it passes through the bleed valve 177.

Excavator 100 is preferably configured such that hydraulic oil passes through bleed valve 177 at the same time as hydraulic oil passes through relief valve 50 . With this configuration, the excavator 100 can cause hydraulic oil to flow into the oil passage 40 at the time when discharge of the hydraulic oil through the relief valve 50 is started. Therefore, the time during which the heated hydraulic oil passes through the oil passage 40 can be lengthened while the warm-up work is being performed.

The excavator 100 is preferably configured to open the bleed valve 177 during warm-up to allow each of the control valves 171-176 arranged in the oil passage 40 to come into contact with hydraulic oil. Specifically, the oil passage 40 is configured to communicate with each of the multiple spool holes formed in the valve housing 17H. With this configuration, the controller 30 can warm not only the valve housing 17H but also the spool portions of the control valves 171-176 during warm-up by executing an opening area adjustment process as shown in FIG. 4. Therefore, the excavator 100 can prevent the spool portions constituting each of the control valves 171-176 from sticking to the spool holes formed in the valve housing 17H of the control valve unit 17 during normal operation after warm-up.

The preferred embodiments of the present invention have been described above in detail. However, the invention is not limited to the embodiments described above. Various modifications or substitutions may be made to the embodiments described above without departing from the scope of the present invention. Further, features described separately can be combined as long as no technical contradiction occurs.

For example, in the above embodiment, the bleed flow rate is controlled by the bleed valve 177, but may be controlled by each of the control valves 171 to 176. That is, each of the control valves 171 to 176 may be configured to function as a bleed valve. Specifically, each of the control valves 171 to 176 may be configured to reduce the bleed flow rate as the amount of movement from the neutral valve position increases. In this case, the bleed valve 177 is omitted. The opening area adjustment process is then executed to adjust the opening area of each of the control valves 171 to 176, rather than the opening area of the bleed valve 177. For example, when warm-up work is being performed by continuing the operation of closing the bucket 6, the controller 30 may control the bleed flow rate passing through the control valve 174 by moving the control valve 174 regardless of the operation of the right operating lever 26R by the operator.

In the above embodiment, the warm-up operation is performed by continuing the operation of moving the boom 4, the arm 5, the bucket 6, etc., but it may be performed by simply switching the bleed valve 177 to the first valve position with the minimum opening area (0% opening). In this case, the controller 30 may increase the discharge amount of the main pump 14 to a predetermined amount and then switch the bleed valve 177 to the first valve position when, for example, a specific switch, which is an example of an input device installed in the cabin 10, is operated. In this configuration, the operator of the excavator 100 does not need to continuously operate the operating device 26 for the warm-up operation. The predetermined amount is, for example, the amount discharged by the right main pump 14R when the bucket closing operation is continued after the bucket 6 is completely closed. This is to allow the discharge pressure of the main pump 14 to reach the relief pressure early and to allow the hydraulic oil to be warmed up early. However, the controller 30 does not need to increase the discharge amount of the main pump 14.

In the above-described embodiment, the oil passage portion of the oil passage 40 where the throttle 18, the control pressure sensor 19, and the bleed valve 177 are arranged (hereinafter referred to as the “bleed oil passage portion”) is shown in FIG. As shown in the figure, it is arranged so as to extend from the branch point B1 and connect to the oil passage 45. However, the bleed oil passage portion may be arranged so as to extend from the upstream side of the branch point B1, may be arranged so as to extend from the upstream side of the branch point B2, and may be arranged so as to extend from the upstream side of the branch point B3. It may be arranged so as to extend from the side. Branch point B1 is a point where the oil passage portion connecting oil passage 40 and control valve 176 branches from oil passage 40, and includes branch point B1L and branch point B1R. Branch point B2 is a point where the oil passage portion connecting oil passage 40 and control valve 175 branches from oil passage 40, and includes branch point B2L and branch point B2R. Branch point B3 is a point where the oil passage portion connecting oil passage 40 and control valve 173 or control valve 174 branches from oil passage 40, and includes branch point B3L and branch point B3R.

For example, the bleed oil passage portion may be arranged to extend from a branch point (not shown) between branch point B1 and branch point B2 to oil passage 45, or may extend from branch point B1 and branch point B2 to branch point B3. The oil passage 45 may be arranged to extend from a branch point (not shown) between the oil passage and the oil passage 45.

Even if the bleed oil passage portion is arranged to extend from the upstream side of branch point B1 as described above, the hydraulic oil flowing through oil passage 40 can adequately warm the control valves 171-176 and their vicinity. This is because the valve housing 17H is a metal casting, which has good thermal conductivity and allows heat to be efficiently transferred from the portion close to the oil passage 40 to the portion far from it.

1: Lower traveling body 1M: Travel hydraulic motor 1ML: Left traveling hydraulic motor 1MR: Right traveling hydraulic motor 2: Swing mechanism 2A: Swing hydraulic motor 3: Upper rotating body 4: Boom 5: Arm 6: Bucket 7: Boom cylinder 8: Arm cylinder 9: Bucket cylinder 10: Cabin 11: Engine 13: Regulator 13L: Left regulator 13R: Right regulator 14: Main pump 14L: Left main pump 14R: Right main pump 15: Pilot pump 17: Control valve unit 17H: Valve housing 18: Throttle 18L: Left throttle 18R: Right throttle 19: Control pressure sensor 19L: Left control pressure sensor 19R: Right control pressure sensor 26: Operation device 26L: Left operating lever 26R: Right operating lever 28: Discharge pressure sensor 28L: Left discharge pressure sensor 28R: Right discharge pressure sensor 29: Operating pressure sensor 29L: Left operating pressure sensor 29R: Right operating pressure sensor 30: Controller 31: Proportional valve 31L: Left proportional valve 31R: Right proportional valve 40-46: Oil passage 40L-44L, 46L: Left oil passage 40R-44R, 46R: Right oil passage 43C: Center oil passage 50: Relief valve 51, 52: Check valve 51L, 52L: Left check valve 51R, 52R: Right check valve 53: Oil cooler 100: Shovel 171-176: Control valve 177: Bleed valve 177L: Left bleed valve 177R: Right bleed valve

Claims (7)

a lower running body;
an upper rotating body rotatably mounted on the lower traveling body;
a hydraulic pump mounted on the upper revolving body;
a hydraulic oil tank mounted on the upper revolving body;
a relief valve mounted on the upper revolving body;
a control valve unit mounted on the upper revolving body;
a first oil passage formed in a valve housing constituting the control valve unit and connecting the hydraulic pump and the hydraulic oil tank;
a second oil passage connecting the hydraulic pump and the hydraulic oil tank via the relief valve;
a bleed valve that controls the flow of hydraulic oil in the first oil passage;
a control device that controls the bleed valve;
The control device controls the bleed valve so that the hydraulic oil passes through the bleed valve when the hydraulic oil is passing through the relief valve during warm-up,
During warm-up, the hydraulic oil passing through the bleed valve is hydraulic oil that comes out of the hydraulic pump, passes through the first oil passage, and passes between a plurality of control valves arranged in the valve housing. and is hydraulic oil that exits the hydraulic pump and does not pass through the relief valve .
shovel. a suction oil passage arranged on the suction side of the hydraulic pump;
an oil temperature sensor attached to the suction oil passage,
The control device causes hydraulic oil to pass through the bleed valve when the value output by the oil temperature sensor is below a predetermined value and when the hydraulic oil is passing through the relief valve during warm-up. controlling the bleed valve to
The excavator according to claim 1. It has a discharge pressure sensor that detects the discharge pressure of the hydraulic pump,
The control device determines that hydraulic oil is passing through the relief valve when the value output by the discharge pressure sensor is equal to or higher than a predetermined value, and controls the bleed valve so that the hydraulic oil passes through the bleed valve. Control,
The excavator according to claim 1 or 2. The hydraulic oil passes through the relief valve and the bleed valve at the same time.
A shovel according to any one of claims 1 to 3. By opening the bleed valve during warm-up, the plurality of control valves disposed in the first oil passage are brought into contact with hydraulic oil;
A shovel according to any one of claims 1 to 4. The first oil passage is connected to the first oil passage regardless of whether the spool portions of the plurality of control valves are in the neutral valve position or when at least one of the spool portions has moved from the neutral valve position. 1, the flow of hydraulic oil flowing through the oil passage is not restricted by the spool portion;
A shovel according to any one of claims 1 to 5. A throttle is disposed between the bleed valve and the hydraulic oil tank,
The control device, during normal operation after a warm-up operation, reduces the discharge amount of the hydraulic pump as the control pressure generated by the throttle increases, and increases the discharge amount of the hydraulic pump as the control pressure decreases.
A shovel according to any one of claims 1 to 6.

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