JP6618495B2 - Hydraulic drive - Google Patents

Description

  The present invention relates to a hydraulic drive device used in a construction machine such as a hydraulic excavator provided with a hydraulic motor, for example.

  In general, a hydraulic excavator as a representative example of a construction machine is a self-propelled lower traveling body, an upper revolving body that is turnably mounted on the lower traveling body, and work provided on the front side of the upper revolving body. And the device. The lower traveling body includes, for example, an endless crawler belt and a travel drive device that includes a hydraulic motor for driving the crawler belt around.

  Here, if the hydraulic excavator is stopped for a long time in an environment where the temperature is low, such as in a cold region, the temperature of the entire hydraulic excavator including the engine, hydraulic equipment, engine oil, hydraulic oil, etc. decreases to the same level as the outside temperature. . On the other hand, engine and hydraulic equipment have poor starting performance at low temperatures. For this reason, in cold regions, for example, a heater is provided in the engine, the engine is warmed up by the heater, and the operating oil is circulated by the main hydraulic pump to raise the temperature of the operating oil in the operating oil tank. Is done.

  However, at this time, unless the hydraulic excavator is caused to travel, the hydraulic oil whose temperature has increased due to circulation on the upper swing body side is not supplied to the travel drive device on the lower travel body side. For this reason, in this case, even when time elapses from the start of the engine, the driving device for driving and the hydraulic oil inside thereof remain in a low temperature state. And if driving | running | working operation | movement is performed from this state, the hydraulic fluid which became high temperature (for example, about 40 degreeC-50 degreeC) by the circulation by the upper turning body side will be low temperature (for example, about -10 degreeC-0 degreeC). There is a possibility of flowing into the driving device for traveling in the state. As a result, a heat shock occurs, and there is a possibility that problems such as galling due to thermal expansion of sliding parts of the hydraulic motor may occur. Moreover, since the hydraulic oil in the driving device for driving is at a low temperature at the start of running, a response delay due to the high viscosity of the hydraulic oil occurs, which may cause the operator to feel uncomfortable.

  In order to prevent such a heat shock and response delay, even when the driving device for traveling is stopped, the traveling oil is supplied to the driving device for traveling by raising the operating oil whose temperature has risen above (upper revolving body side). It is conceivable to warm up the driving device for the vehicle. For example, in Patent Document 1, the hydraulic oil for traveling is supplied by supplying the pressure oil from the pilot pump to one of the two drain ports of the traveling hydraulic motor and discharging it from the other drain port. A technique for warming up the motor is described. According to this technique, the hydraulic oil can be warmed up by circulating the pressure oil from the pilot pump in the case of the hydraulic motor.

JP 2002-276618 A (Patent No. 3898456)

  According to the prior art, the traveling hydraulic motor is a fixed displacement hydraulic motor. On the other hand, the variable displacement hydraulic motor requires a control valve (shift pilot pressure control valve) and a pipe line (shift pilot line) for shifting. For this reason, in addition to adopting a variable displacement hydraulic motor as a traveling hydraulic motor, adding a new control valve and pipe for warming up as in Patent Document 1 makes the structure complicated. Cost may increase.

  On the other hand, it is conceivable to warm up the variable displacement hydraulic motor with the following configuration. That is, between the “shift pilot line for supplying a shift pilot pressure to the variable displacement hydraulic motor” and the “drain line for discharging the drain of the variable displacement hydraulic motor to the hydraulic oil tank”, Provide a circuit (pipe) that communicates with each other. When warming up, the shifting pilot pressure is supplied to the shifting pilot line. That is, it is conceivable that the variable displacement hydraulic motor is warmed up by supplying the shifting pilot pressure from the shifting pilot line toward the drain circuit of the variable displacement hydraulic motor.

  However, in this case, the following inconvenience may occur, for example, by simply communicating between the shifting pilot line and the drain line. In other words, if shifting pilot pressure is supplied to the shifting pilot line in order to shift the variable displacement hydraulic motor during traveling, this shifting pilot pressure will always leak into the drain line, reducing efficiency. there's a possibility that. In addition to this, leakage of the shifting pilot pressure may adversely affect the responsiveness of the shift control during traveling (decrease the responsiveness).

  An object of the present invention is to provide a hydraulic drive device capable of warming up a variable displacement hydraulic motor, and capable of suppressing a complicated structure, an increase in cost, a decrease in efficiency, and a decrease in response of a shift. Is to provide.

  In order to solve the above-described problems, the present invention provides a variable displacement hydraulic motor having a displacement variable portion and rotationally driven by pressure oil from a hydraulic power source, and a pair of connecting the variable displacement hydraulic motor to the hydraulic power source. A direction control valve that is provided in the middle of the supply / discharge passage and switches the direction of the pressure oil supplied to and discharged from the hydraulic source to the variable displacement hydraulic motor, and between the direction control valve and the variable displacement hydraulic motor. A counter balance valve located in the middle of the pair of supply / discharge passages, a variable capacity actuator that drives a variable capacity section of the variable capacity hydraulic motor to change the motor capacity, and supplies the variable capacity actuator A displacement control valve for switching pressure oil, a pilot pressure control valve for controlling a pilot pressure from a pilot pump to switch the displacement control valve, the pilot pressure control valve, A variable speed pilot line that is connected to an amount control valve and supplies pilot pressure from the pilot pressure control valve to the displacement control valve; and a drain from the variable displacement hydraulic motor; And a drain pilot line that discharges to a tank that constitutes a warming pilot connected between the shift pilot pipe and the drain pipe via the counter balance valve The counter balance valve communicates the speed change pilot line and the drain line via the warm-up pilot line when the variable displacement hydraulic motor is stopped. When the variable displacement hydraulic motor is driven, the warm-up pilot pipeline is cut off.

  According to the present invention, it is possible to warm up the variable displacement hydraulic motor, and it is possible to suppress the complexity of the structure, the increase in cost, the decrease in efficiency, and the decrease in the response of shifting.

  That is, when the variable displacement hydraulic motor is stopped, the shift pilot line and the drain line are communicated with each other via the warm-up pilot line by the counter balance valve. In this state, when pressure oil from the pilot pump is supplied to the pilot line for speed change through the pilot pressure control valve, this pressure oil becomes pressure oil for warm-up (warm-up pressure oil) and shifts. Flows from the pilot line to the drain line through the warm-up pilot line. At this time, this pressure oil (warm-up pressure oil) passes through the variable displacement hydraulic motor (the casing thereof), whereby the variable displacement hydraulic motor can be warmed up. In this case, since it is not necessary to add a new control valve for warming up and a dedicated pipe line as in Patent Document 1, it is possible to suppress a complicated structure and an increase in cost.

  On the other hand, the counter balance valve shuts off the warm-up pilot pipeline when the variable displacement hydraulic motor is driven. As a result, when the variable displacement hydraulic motor is driven, even if pressure oil from the pilot pump is supplied to the speed change pilot line through the pilot pressure control valve, the pressure oil is warmed from the speed change pilot line. Supply to the drain line via the machine pilot line is prevented. For this reason, when the variable displacement hydraulic motor is being driven, it is possible to prevent the shifting pilot pressure for shifting the variable displacement hydraulic motor from leaking to the drain line. As a result, it is possible to suppress a decrease in efficiency and a decrease in the response of shifting.

1 is a front view showing a hydraulic excavator according to a first embodiment. FIG. 2 is a hydraulic circuit diagram of the hydraulic excavator in FIG. 1. It is the hydraulic circuit figure which expanded the (III) part in FIG. It is a longitudinal cross-sectional view which shows the hydraulic motor for driving | running | working. It is a flowchart which shows the control processing by the controller in FIG. It is a flowchart which shows the control processing of the controller by 2nd Embodiment. It is a flowchart which shows the control processing of the controller by a 1st modification. It is a flowchart which shows the control processing of the controller by a 2nd modification.

  Hereinafter, a case where a hydraulic drive device according to an embodiment of the present invention is applied to a hydraulic drive device of a construction machine (hydraulic excavator) will be described as an example and described with reference to the accompanying drawings.

  1 to 5 show a first embodiment. In FIG. 1, a hydraulic excavator 1, which is a typical example of a construction machine, swivels on a crawler-type lower traveling body 2 capable of self-propelling, a turning device 3 provided on the lower traveling body 2, and a lower traveling body 2. The upper revolving body 4 is mounted so as to be able to swivel via the device 3, and the multi-joint structure working device 5 is provided on the front side of the upper revolving body 4 and performs excavation work or the like.

  At this time, the lower traveling body 2 and the upper swing body 4 constitute a vehicle body of the excavator 1. The working device 5, also referred to as a work machine or a front, includes, for example, a boom 5A, an arm 5B, a bucket 5C as a work tool, a boom cylinder 5D, an arm cylinder 5E, and a bucket cylinder 5F as a work tool cylinder. It is comprised by. The working device 5 moves up and down by extending or contracting the cylinders 5D, 5E, and 5F, which are hydraulic cylinders.

  The undercarriage 2 is provided on the opposite side of the track frame 2A, the drive wheels 2B provided on both the left and right sides of the track frame 2A, and the drive wheels 2B on the left and right sides of the track frame 2A. And a crawler belt 2D wound around the drive wheel 2B and the idler wheel 2C (both shown only on the left side). The left and right drive wheels 2B are driven by travel hydraulic motors 33 and 56 (see FIG. 2) of left and right travel drive devices 32 and 55, which will be described later.

  The upper swing body 4 is mounted on the lower traveling body 2 via a swing device 3 including a swing bearing, a swing hydraulic motor, a speed reduction mechanism, and the like. The upper swing body 4 includes a swing frame 6 that is a support structure (base frame) for the upper swing body 4, a cab 7 mounted on the swing frame 6, a counterweight 8, and the like. In this case, an engine 12, hydraulic pumps 13, 14, and 20, a hydraulic oil tank 15, a control valve device 22 (see FIG. 2) and the like, which will be described later, are mounted on the turning frame 6.

  The turning frame 6 is attached to the lower traveling body 2 through the turning device 3. On the left side of the front part of the swivel frame 6 is provided a cab 7 whose inside is a cab. In the cab 7, a driver's seat on which an operator is seated is provided. Around the driver's seat, an operating device 27 for operating the excavator 1, a tilt changeover switch 60 (see FIG. 2), and the like are provided. The operating device 27 outputs a pilot signal (pilot pressure) corresponding to the operator's operation (lever operation, pedal operation) to the control valve device 22. As a result, the operator operates (drives) the traveling hydraulic motors 33 and 56 of the traveling drive devices 32 and 55 (see FIG. 2), the cylinders 5D and 5E and 5F of the work device 5, and the swing hydraulic motor of the swing device 3. ).

  A controller 62 (see FIG. 2), which will be described later, is provided in the cab 7 below the driver's seat. On the other hand, a counterweight 8 for balancing the weight with the working device 5 is provided on the rear end side of the revolving frame 6.

  Next, a hydraulic drive device for driving the hydraulic excavator 1 will be described with reference to FIGS. 2 to 5 in addition to FIG.

  As shown in FIG. 2, the excavator 1 includes a hydraulic circuit 11 that operates (drives) the excavator 1 based on the pressure oil supplied from the hydraulic pumps 13 and 14. The hydraulic circuit 11 includes an engine 12, hydraulic pumps 13, 14, and 20, a hydraulic oil tank 15, a center joint 19, a control valve device 22, an operation device 27, travel drive devices 32 and 55, a controller 62, and the like. The hydraulic circuit 11 shown in FIG. 2 mainly shows a circuit (that is, a traveling hydraulic drive device) for traveling the lower traveling body 2 in order to avoid complication of the drawing. In other words, the hydraulic circuit 11 shown in FIG. 2 drives a circuit for driving the working device 5 (that is, a working hydraulic drive device) and drives the turning device 3 (upper turning with respect to the lower traveling body 2). The circuit for turning the body 4 (that is, the turning hydraulic drive device) is omitted.

  The engine 12 is mounted on the turning frame 6. The engine 12 is configured by an internal combustion engine such as a diesel engine, for example. A first hydraulic pump 13, a second hydraulic pump 14, and a pilot hydraulic pump 20 are attached to the output side of the engine 12. These hydraulic pumps 13, 14, and 20 are rotationally driven by the engine 12. The drive source (power source) for driving the hydraulic pumps 13, 14, and 20 can be constituted by the engine 12 alone as an internal combustion engine, for example, by an engine and an electric motor, or an electric motor alone. Also good.

  The first hydraulic pump 13 and the second hydraulic pump 14 (hereinafter also referred to as hydraulic pumps 13 and 14) are mechanically connected to the engine 12 (that is, capable of transmitting power). The hydraulic pumps 13 and 14 are the main hydraulic pumps of the hydraulic circuit 11. The hydraulic pumps 13 and 14 are constituted by, for example, variable displacement swash plate type, oblique axis type or radial piston type hydraulic pumps. The hydraulic pumps 13 and 14 are connected via a control valve device 22 to traveling hydraulic motors 33 and 56 that serve as hydraulic actuators, turning hydraulic motors, cylinders 5D, 5E, and 5F (hereinafter also referred to as hydraulic actuators 5D-56). Has been.

  Here, the first hydraulic pump 13 is a traveling hydraulic motor 33 (hereinafter, also referred to as the left traveling hydraulic motor 33) of the traveling drive device 32 (hereinafter also referred to as the left traveling drive device 32) on the left side of the excavator 1. Supply pressure oil. Moreover, although illustration is abbreviate | omitted, the 1st hydraulic pump 13 supplies pressure oil to the hydraulic motor for rotation, the boom cylinder 5D, and the arm cylinder 5E, for example. As shown in FIG. 2, the first hydraulic pump 13 discharges hydraulic oil stored in the hydraulic oil tank 15 to the first discharge pipe 16 as pressure oil.

  The pressure oil discharged to the first discharge pipe 16 is supplied to the left traveling hydraulic motor 33 via the control valve device 22 and the center joint 19. The pressure oil supplied to the left traveling hydraulic motor 33 returns to the hydraulic oil tank 15 via the center joint 19, the control valve device 22 and the return pipe 17. Thus, the 1st hydraulic pump 13 comprises the 1st hydraulic power source with the hydraulic oil tank 15 which stores hydraulic oil.

  On the other hand, the second hydraulic pump 14 is the same as the first hydraulic pump 13. The second hydraulic pump 14 is connected to a traveling hydraulic motor 56 (hereinafter also referred to as a right traveling hydraulic motor 56) of a traveling drive device 55 (hereinafter also referred to as a right traveling drive device 55) on the right side of the excavator 1. Supply pressure oil. Moreover, although illustration is abbreviate | omitted, the 2nd hydraulic pump 14 supplies pressure oil to the boom cylinder 5D and the bucket cylinder 5F, for example. As shown in FIG. 2, the second hydraulic pump 14 discharges the hydraulic oil stored in the hydraulic oil tank 15 to the second discharge pipe 18 as pressure oil. The second hydraulic pump 14 constitutes a second hydraulic power source together with the hydraulic oil tank 15.

  The center joint 19 is provided between the lower traveling body 2 and the upper swing body 4. The center joint 19 circulates oil (hydraulic oil, pressure oil) between the upper swing body 4 side and the lower travel body 2 side regardless of the swing of the upper swing body 4 with respect to the lower travel body 2. .

  The pilot hydraulic pump 20 as a pilot pump is mechanically connected to the engine 12 like the hydraulic pumps 13 and 14. The pilot hydraulic pump 20 is configured by, for example, a fixed displacement gear pump. The pilot hydraulic pump 20 discharges hydraulic oil stored in the hydraulic oil tank 15 into the pilot discharge pipe 21 as pressure oil. That is, the pilot hydraulic pump 20 constitutes a pilot hydraulic power source together with the hydraulic oil tank 15.

  The pilot hydraulic pump 20 supplies pressure oil (hereinafter also referred to as shifting pilot pressure) to the tilt switching valves 51 and 51 of the traveling hydraulic motors 33 and 56 via a pilot pressure control valve 58 described later. In addition, as will be described later, the pilot hydraulic pump 20 applies pressure oil (transmission pilot that serves as warm-up pressure oil) to the traveling hydraulic motors 33 and 56 via the pilot pressure control valve 58 and counter balance valves 49 and 49. Pressure). Further, the pilot hydraulic pump 20 applies pressure oil (hereinafter referred to as operation pilot pressure) to the control valve device 22 (direction control valves 23 and 24) via the operation device 27 (travel lever / pedal operation devices 28 and 29). (Also called).

  The control valve device 22 is a control valve group including a plurality of directional control valves 23 and 24. The control valve device 22 shown in FIG. 2 mainly shows the direction control valves 23 and 24 for travel, that is, the direction control valve 23 for left travel and the direction control valve 24 for right travel. In other words, the control valve device 22 shown in FIG. 2 includes a working direction control valve (a boom direction control valve, an arm direction control valve, and a bucket direction control valve), and a turning direction control valve (turning). The directional control valve is omitted. Similarly, the operating device 27 shown in FIG. 2 mainly shows the operating devices 28 and 29 for traveling, that is, the left traveling lever / pedal operating device 28 and the right traveling lever / pedal operating device 29. In other words, the operating device 27 shown in FIG. 2 omits the working lever operating device (left lever operating device, right lever operating device).

  The control valve device 22 distributes the pressure oil discharged from the hydraulic pumps 13 and 14 to the hydraulic actuators 5D-56. That is, the control valve device 22 is supplied from the hydraulic pumps 13 and 14 to the hydraulic actuator 5D- in response to a switching signal (operating pilot pressure) by the operation (lever operation, pedal operation) of the operation device 27 disposed in the cab 7. The direction of the pressure oil supplied to 56 is controlled. Accordingly, the hydraulic actuator 5D-56 is driven by the pressure oil (operating oil) supplied (discharged) from the hydraulic pumps 13 and 14.

  Here, the left travel direction control valve 23 of the control valve device 22 includes a pair of left supply / discharge passages (left supply / discharge passages) 25A and 25B that connect the left travel hydraulic motor 33 to the first hydraulic pump 13. It is provided on the way. The left traveling directional control valve 23 is configured by a pilot operated directional control valve, for example, a hydraulic pilot directional control valve at 4 port 3 position (or 6 port 3 position). The left travel direction control valve 23 switches between supply and discharge of pressure oil to the left travel hydraulic motor 33 between the first hydraulic pump 13 and the left travel hydraulic motor 33.

  That is, the left travel direction control valve 23 switches the direction of the pressure oil supplied to and discharged from the first hydraulic pump 13 to the left travel hydraulic motor 33. Thereby, the left travel direction control valve 23 causes the left travel hydraulic motor 33 to rotate forward or backward. A switching signal based on the operation of the left travel lever / pedal operating device 28 is supplied to the hydraulic pilot portions 23A and 23B of the left travel direction control valve 23. Thus, the left travel direction control valve 23 is switched from the neutral position (A) to the switching positions (B) and (C).

  The right travel direction control valve 24 of the control valve device 22 is provided in the middle of a pair of right supply / discharge passages (right supply / discharge passages) 26A and 26B that connect the right travel hydraulic motor 56 to the second hydraulic pump 14. It has been. The right travel direction control valve 24 is the same as the left travel direction control valve 23, and switches the direction of the pressure oil supplied to and discharged from the second hydraulic pump 14 to the right travel hydraulic motor 56. A switching signal based on the operation of the right travel lever / pedal operating device 29 is supplied to the hydraulic pilot portions 24A, 24B of the right travel direction control valve 24.

  The operation device 27 includes travel lever / pedal operation devices 28 and 29 (hereinafter also referred to as travel operation devices 28 and 29) serving as travel operation devices, and a work lever operation device (not shown) serving as a work operation device. )). The travel operation devices 28 and 29 are disposed in the cab 7 of the upper swing body 4, more specifically, in front of the driver's seat. The working lever operating device is arranged on both the left and right sides of the driver's seat.

  The travel operation devices 28 and 29 are constituted by, for example, lever / pedal type pressure reducing valve type pilot valves. The traveling operation devices 28 and 29 are supplied with pressure oil from the pilot hydraulic pump 20 through the pilot discharge pipe 21. The travel operation devices 28 and 29 output a switching signal corresponding to the lever operation and pedal operation by the operator to the control valve device 22.

  Here, the left travel operation device 28 switches the left travel direction control valve 23. That is, the left travel operation device 28 is operated by an operator, and the left travel pilot pressure, which is an operation pilot pressure (switching signal) proportional to the operation amount, is converted into a hydraulic pilot of the left travel direction control valve 23. Supply (output) to the units 23A and 23B. Thereby, the switching position of the left travel direction control valve 23 is switched. On the other hand, the right travel operation device 29 switches the right travel direction control valve 24.

  The pressure sensor 30 is provided between the travel operation devices 28 and 29 and the travel direction control valves 23 and 24 (oil paths thereof) via shuttle valves 31A, 31B, and 31C. The pressure sensor 30 detects the traveling pilot pressure Pt (in other words, the driving pressure Pt for switching and driving the traveling direction control valves 23, 24) taken out via the shuttle valves 31A, 31B, 31C. That is, the pressure sensor 30 detects the high-pressure side pressure of the left traveling pilot pressure and the right traveling pilot pressure as the traveling pilot pressure Pt.

  The pressure sensor 30 is connected to the controller 62. The pressure sensor 30 outputs a signal corresponding to the traveling pilot pressure Pt to the controller 62. Based on the traveling pilot pressure Pt detected by the pressure sensor 30, the controller 62 determines, for example, whether or not the traveling operation devices 28 and 29 are operated. That is, the controller 62 determines that the traveling operation devices 28 and 29 are being operated when the traveling pilot pressure Pt is greater than a preset threshold Pa (when Pt> Pa). The threshold value Pa is obtained in advance by experiments, calculations, simulations, or the like so that it can be accurately determined whether or not the operating devices for traveling 28 and 29 are being operated.

  The left travel drive device 32 rotationally drives the left drive wheel 2 </ b> B based on the pressure oil supplied from the first hydraulic pump 13. The left traveling hydraulic motor 33 of the left traveling drive device 32 is connected to the first hydraulic pump 13 and the hydraulic oil tank 15 via the left supply / discharge conduits 25A and 25B. A left travel direction control valve 23 is provided in the middle of the left supply / discharge pipes 25A and 25B.

  As shown in FIG. 3, the left travel drive device 32 (hereinafter also simply referred to as the travel drive device 32) includes a left travel hydraulic motor 33 (hereinafter also simply referred to as the hydraulic motor 33) and a left brake valve 44 (hereinafter referred to as the hydraulic drive device 32). Simply referred to as a brake valve 44). That is, the driving device 32 for traveling travels to the hydraulic motor 33 that can rotate in both directions by reversing the inlet and outlet of the pressure oil to the inflow / outlet of the hydraulic motor 33 (motor ports 47A and 47B). Is connected to a brake valve 44.

  The hydraulic motor 33 is driven to rotate by pressure oil from the hydraulic pump 13. Here, the hydraulic motor 33 is a variable displacement hydraulic motor. More specifically, as shown in FIG. 4, the hydraulic motor 33 is constituted by an axial piston type swash plate type hydraulic motor having a swash plate 42 as a capacity variable portion. The hydraulic motor 33 includes a motor casing 34, an output shaft 35, a cylinder block 36, a piston 38, a shoe 39, a valve plate 40, and a variable capacity mechanism 41. The hydraulic motor 33 can rotate the output shaft 35 with the pressure oil supplied from the hydraulic pump 13, and can change the rotation speed of the output shaft 35 by the variable capacity mechanism 41.

  The motor casing 34 forms an outer shell of the hydraulic motor 33. In the motor casing 34, an output shaft 35, a cylinder block 36, a valve plate 40, a swash plate 42, and the like are arranged. The output shaft 35 is rotatably provided on the motor casing 34. The cylinder block 36 is located in the motor casing 34 and is provided on the outer peripheral side of the output shaft 35. The cylinder block 36 is splined to the output shaft 35 and rotates integrally with the output shaft 35. The cylinder block 36 has a plurality of cylinders 37 that are spaced apart in the circumferential direction and extend in the axial direction. A piston 38 is slidably inserted into the cylinder 37. The cylinder 37 communicates with the port 37A.

  The plurality of pistons 38 are inserted into the respective cylinders 37 of the cylinder block 36 so as to be slidable in the axial direction. The piston 38 reciprocates in the cylinder 37 by the rotation of the cylinder block 36. The plurality of shoes 39 are swingably provided on the front end side (projecting end side) of each piston 38. When the shoe 39 is pressed against the surface of the swash plate 42 by the piston 38, the shoe 39 slides on the swash plate 42 so as to draw an annular locus as the cylinder block 36 rotates.

  The valve plate 40 is provided between the motor casing 34 and the cylinder block 36. The valve plate 40 has a pair of supply / discharge ports 40 </ b> A and 40 </ b> B that intermittently communicate with the cylinders 37 of the cylinder block 36. Each supply / discharge port 40A, 40B communicates with the supply / discharge conduit 25A, 25B. In the port 37A of the cylinder block 36, the high pressure side port (pressure oil inflow side) and the low pressure side port (pressure oil outflow side) are separated by the supply / discharge ports 40A and 40B of the valve plate 40. That is, the state of the pressure oil acting on the port 37A of the cylinder block 36 is switched according to the rotation angle of the cylinder block 36.

  The variable capacity mechanism 41 is provided in the motor casing 34. The capacity variable mechanism 41 includes a swash plate 42 as a capacity variable section and a tilt actuator 43 as a capacity variable actuator. The capacity variable mechanism 41 adjusts the capacity of the pressure oil supplied into each cylinder 37 of the cylinder block 36 by changing the tilt angle of the swash plate 42 by the tilt actuator 43, and the rotational speed of the output shaft 35. The output torque is changed.

  The swash plate 42 is located on the protruding end side of each piston 38 and is provided in the motor casing 34 so as to be tiltable. The swash plate 42 is formed in a disc shape surrounding the output shaft 35. The rear surface side of the swash plate 42 is supported by the motor casing 34 so as to be tiltable, and the front surface side of the swash plate 42 slides so that each shoe 39 draws an annular locus as the cylinder block 36 rotates. It is a moving surface.

  Here, the swash plate 42 always holds the large tilt position shown in FIG. 4 by the resultant force (pressing force) of the pressing force acting from each piston 38. On the other hand, the swash plate 42 is tilted to the small tilt position by being pressed by the tilt actuator 43. In this case, when the swash plate 42 is in the large tilt position (the position shown in FIG. 4), the stroke amount (maximum / minimum stroke difference) of the piston 38 increases, so that the output shaft 35 rotates at a low speed with high torque. On the other hand, when the swash plate 42 is in the small tilt position, the stroke amount of the piston 38 is reduced, whereby the supply flow rate (motor displacement capacity) necessary for the rotation of the hydraulic motor 33 is reduced, and the output shaft 35 has a low torque. Rotate at high speed.

  The tilting actuator 43 drives the swash plate 42 of the hydraulic motor 33 to change the motor capacity. Here, the tilting actuator 43 is fitted into a tilting cylinder 43A which is radially spaced from the output shaft 35 and is drilled in the motor casing 34, and a proximal end side is slidably fitted into the tilting cylinder 43A. The tilting piston 43B (servo piston) whose side abuts against the back surface of the swash plate 42 is formed. The tilt actuator 43 tilts the swash plate 42 by a large amount when the tilt piston 43B presses the back side of the swash plate 42 in accordance with the pressure oil supplied from the tilt switching valve 51 into the tilt cylinder 43A. The rotation speed of the output shaft 35 is changed by tilting between the position and the small tilt position.

  As shown in FIG. 3, the brake valve 44 and the hydraulic motor 33 constitute a traveling drive device 32. The brake valve 44 includes a pair of valve ports 45A and 45B, a pilot pressure port 46, a pair of motor ports 47A and 47B, a pair of check valves 48A and 48B, a counter balance valve 49, a high pressure selection valve 50, It has a tilt switching valve 51 as a capacity control valve and a pair of relief valves 53A, 53B. The check valves 48A and 48B, the counter balance valve 49, the high pressure selection valve 50, the tilt switching valve 51, and the relief valves 53A and 53B are provided integrally with the motor casing 34 of the hydraulic motor 33, for example.

  The valve ports 45A and 45B are open to the motor casing 34, for example. The valve ports 45 </ b> A and 45 </ b> B are connected to the hydraulic pump 13 or the hydraulic oil tank 15 according to the switching position of the direction control valve 23. The pilot pressure port 46 opens, for example, in the motor casing 34. The pilot pressure port 46 is connected to the pilot hydraulic pump 20 or the hydraulic oil tank 15 according to the switching position of the pilot pressure control valve 58. The motor ports 47A and 47B are connected to the supply / discharge ports 40A and 40B of the valve plate 40.

  The check valves 48A and 48B are located between the hydraulic motor 33 and the direction control valve 23, and are provided in the middle of the supply / discharge lines 25A and 25B. The check valves 48A and 48B are poppet type check valves. The check valves 48A and 48B pass pressure oil flowing from the valve ports 45A and 45B to the motor ports 47A and 47B, while blocking pressure oil flowing from the motor ports 47A and 47B to the valve ports 45A and 45B. Operate.

  The counter balance valve 49 is provided in the middle of the supply / discharge lines 25A and 25B so as to be in parallel with the check valves 48A and 48B. That is, the counter balance valve 49 is located between the direction control valve 23 and the hydraulic motor 33 and is provided in the middle of the pair of supply / discharge lines 25A and 25B. The counter balance valve 49 is switched substantially in conjunction with the directional control valve 23 due to the differential pressure between the supply / exhaust pipes 25A and 25B, and is closed during the inertial rotation of the hydraulic motor 33 and is supplied before and after the hydraulic motor 33. A brake pressure is generated in the exhaust pipe 25A or the supply / discharge pipe 25B.

  Here, the counter balance valve 49 is a 6-port 3-position spring center type spool type switching valve. The counter balance valve 49 communicates an oil path between the motor port 47A and the valve port 45A with a neutral position (a) that blocks the oil path between the valve ports 45A and 45B and the motor ports 47A and 47B. The drive position (b) for blocking the oil path between the valve port 45B and the motor port 47B is connected to the oil path between the motor port 47B and the valve port 45B, and the oil between the valve port 45A and the motor port 47A. It is possible to switch between the driving position (c) for blocking the road.

  The high pressure selection valve 50 is constituted by a shuttle valve. The high pressure selection valve 50 is located between the hydraulic motor 33 and the counter balance valve 49 and is provided between the supply / discharge pipes 25A and 25B. The high pressure selection valve 50 selects the pressure oil on the high pressure side of the supply / discharge pipes 25 </ b> A and 25 </ b> B connected to the hydraulic motor 33, and sends the selected pressure oil to the tilt actuator 43 via the tilt switching valve 51. Supply.

  The tilt switching valve 51 is installed between the high pressure selection valve 50 and the tilt actuator 43. That is, the tilt switching valve 51 is provided in the middle of the oil passage 52 that connects the high pressure selection valve 50 and the tilt cylinder 43 </ b> A of the tilt actuator 43. The tilt switching valve 51 switches pressure oil supplied to the tilt actuator 43. The tilt switching valve 51 is configured as a 3-port 2-position hydraulic pilot switching valve (direction control valve) having a hydraulic pilot section 51A. The tilt switching valve 51 has a neutral position (d) for connecting the oil passage 52 to the drain port 54 and the oil passage 52 as a high-pressure selection valve in accordance with a pilot signal (shift pilot pressure) supplied to the hydraulic pilot portion 51A. 50 to the drive position (e) connected to 50.

  When the tilt switching valve 51 is in the neutral position (d), the supply of pressure oil from the high pressure selection valve 50 to the tilt cylinder 43A is shut off, and the tilt cylinder 43A communicates with the drain port 54. As a result, the tilting piston 43B is deactivated and the pressing force acting on the swash plate 42 is suppressed, and the swash plate 42 holds the large tilt position (maximum motor tilt). On the other hand, when the tilt switching valve 51 is in the drive position (e), the pressure oil flowing through the high-pressure side supply / discharge line 25A (25B) selected by the high-pressure selection valve 50 out of the supply / discharge lines 25A, 25B. A part of the oil is supplied to the tilting cylinder 43 </ b> A through the oil passage 52. As a result, the tilting piston 43B is activated to press the swash plate 42, and the swash plate 42 holds the small tilt position (motor tilt minimum).

  The transmission pilot pressure P is supplied from the pilot pressure control valve 58 through the pilot pressure port 46 to the hydraulic pilot portion 51 </ b> A of the tilt switching valve 51. Here, the minimum speed change pilot pressure (minimum driving pressure) necessary for switching the tilt switching valve 51 from the neutral position (d) to the driving position (e) is P0. In this case, when a shift pilot pressure P (≧ P0) of P0 or more acts on the hydraulic pilot portion 51A of the tilt switching valve 51, the tilt switching valve 51 moves from the neutral position (d) to the drive position (e), Motor tilt is minimized. On the other hand, when the shift pilot pressure P is smaller than P0, that is, when the shift pilot pressure P <P0, the tilt switching valve 51 does not move to the drive position (e), and the motor tilt is maximum. It remains.

  The relief valves 53A and 53B are located between the hydraulic motor 33 and the counter balance valve 49, and are provided in the middle of the supply / discharge pipes 25A and 25B. The relief valves 53A and 53B are opened when the brake pressure generated in the supply / discharge pipe 25A or the supply / discharge pipe 25B during inertia rotation of the hydraulic motor 33 rises to a predetermined set pressure, and the excess pressure at this time is relieved. To do.

  That is, the relief valves 53 </ b> A and 53 </ b> B are installed for protection of the traveling drive device 32. When the motor port pressure of one motor port 47A (47B) exceeds a specified value (set pressure) among the pair of motor ports 47A and 47B, the relief valves 53A and 53B supply pressure oil to the other (opposite) motor port. By flowing out to 47B (47A), the driving device 32 for traveling is prevented from being damaged by high pressure.

  Here, for example, the valve port 45A is on the high pressure side and the valve port 45B is on the low pressure side. In this case, the flow of the pressure oil in the brake valve 44 is such that the pressure oil flowing from the high pressure side valve port 45A passes through the check valve 48A and flows to the hydraulic motor 33 (valve plate high pressure side port) via the motor port 47A. The hydraulic motor 33 is driven. At this time, the counter balance valve 49 is held at the drive position (c), and the flow path in the counter balance valve 49 that flows from the valve port 45A to the motor port 47A is blocked. The pressure oil flowing out from the hydraulic motor 33 (valve plate low pressure side port) flows through the flow path in the drive position (c) of the counter balance valve 49 and flows out from the low pressure side valve port 45B. The flow path of the check valve 48B that flows from the motor port 47B to the valve port 45B is blocked. As described above, in the brake valve 44, the pressure oil passes through the check valve 48A (48B) in the inflow side oil passage of the hydraulic motor 33 and passes through the counter balance valve 49 in the outflow side oil passage. Take.

  The drain port 54 opens, for example, in the motor casing 34 of the hydraulic motor 33. The drain port 54 discharges oil (drain) leaking from the clearance of the sliding part of the internal parts including the piston 38 in the hydraulic motor 33 from the hydraulic motor 33. The drain port 54 is connected to the hydraulic oil tank 15 via a drain pipe line 57.

  On the other hand, as shown in FIG. 2, the right traveling drive device 55 rotationally drives the right drive wheel based on the pressure oil supplied from the second hydraulic pump 14. The right traveling hydraulic motor 56 of the right traveling drive device 55 is connected to the hydraulic pump 14 and the hydraulic oil tank 15 via the right supply / discharge conduits 26A and 26B. A right travel direction control valve 24 is provided in the middle of the right supply / discharge pipes 26A and 26B. The right driving device 55 is the same as the left driving device 32. Regarding the right driving device 55 (hereinafter, also simply referred to as the driving device 55), the same components as those of the left driving device 32 are denoted by the same reference numerals, and further description thereof is omitted. In this case, a right traveling hydraulic motor 56 (hereinafter, also simply referred to as a hydraulic motor 56) is given a different reference from the left traveling hydraulic motor 33, but has the same configuration as the left traveling hydraulic motor 33.

  The drain pipe line 57 connects between the drain port 54 of the travel drive devices 32 and 55 (hydraulic motors 33 and 56) and the hydraulic oil tank 15. The drain line 57 discharges the drain from the driving devices 32 and 55 including the hydraulic motors 33 and 56 to the hydraulic oil tank 15. That is, the drain from the driving devices 32 and 55 for traveling returns to the hydraulic oil tank 15 through the drain pipe line 57.

  The pilot pressure control valve 58 switches the tilt switching valve 51 of the travel drive devices 32 and 55. For this purpose, the pilot pressure control valve 58 controls the pressure oil (pilot pressure) from the pilot hydraulic pump 20. That is, the pilot pressure control valve 58 controls the transmission pilot pressure P supplied to the tilt switching valve 51 in order to switch the motor tilt of the travel drive devices 32 and 55 (hydraulic motors 33 and 56). The pilot pressure control valve 58 is, for example, a 3-port 2-position electromagnetic switching valve (electromagnetic proportional control valve) composed of a proportional electromagnetic valve, and includes an electromagnetic pilot portion 58A (solenoid).

  The input side of the pilot pressure control valve 58 is connected to the pilot hydraulic pump 20 via the pilot discharge line 21. The output side of the pilot pressure control valve 58 is connected to the tilt switching valve 51 (the hydraulic pilot portion 51A thereof) via the pilot pressure port 46 of the travel drive devices 32 and 55. The electromagnetic pilot part 58 </ b> A of the pilot pressure control valve 58 is connected to the controller 62. The pilot pressure control valve 58 can output pressure oil (shift pilot pressure P) having a pressure P proportional to the electric power W supplied from the controller 62. On the other hand, when the electric power W is not supplied from the controller 62, the pilot pressure control valve 58 makes the pilot pressure port 46 communicate with the hydraulic oil tank 15 as shown in FIG.

  The speed change pilot pipe 59 is provided between the pilot pressure control valve 58 and the tilt switching valve 51 of the travel drive devices 32 and 55. That is, the speed change pilot pipe 59 is a pipe connecting the pilot pressure control valve 58 and the tilt switching valve 51. The transmission pilot line 59 supplies the pilot pressure P from the pilot pressure control valve 58 to the tilt switching valve 51. Further, as will be described later, a warm-up pilot pipeline 64 to be described later is connected in the middle of the shifting pilot pipeline 59. In this case, the speed change pilot line 59 supplies pressure oil (speed change pilot pressure P) from the pilot pressure control valve 58 to the warm-up pilot line 64 via the counter balance valve 49.

  A tilt changeover switch 60 as a capacity changeover switch (speed changeover switch) is installed in the cab 7. The tilt changeover switch 60 is connected to the controller 62. The tilt changeover switch 60 switches the motor capacity (motor tilt state) of the travel drive devices 32 and 55 (hydraulic motors 33 and 56). That is, the operator can adjust the driving speed (rotational speed) of the driving devices 32 and 55 for traveling by operating the tilt changeover switch 60.

  In this case, the tilt changeover switch 60 is, for example, two selected positions (travel mode): a low speed position (low speed mode) where the excavator 1 (lower traveling body 2) travels at a low speed and a high speed position (high speed mode) where the hydraulic excavator 1 travels at high speed. )have. When the tilt changeover switch 60 is switched (set) to the low speed position, the motor capacity becomes large (large tilt), and the hydraulic motors 33 and 56 can be rotated at low speed. On the other hand, when the tilt changeover switch 60 is switched (set) to the high speed position, the motor capacity is small (small tilt), and the hydraulic motors 33 and 56 can be rotated at high speed.

  The oil temperature sensor 61 is installed in the hydraulic oil tank 15. The oil temperature sensor 61 detects (measures) the temperature T (hereinafter also referred to as oil temperature T) of the hydraulic oil in the hydraulic oil tank 15. The oil temperature sensor 61 is connected to the controller 62. The oil temperature sensor 61 outputs a signal corresponding to the oil temperature T to the controller 62. As will be described later, the controller 62 warms up the hydraulic motors 33 and 56 based on the oil temperature T detected by the oil temperature sensor 61.

  The controller 62 is a control device that controls (electronically controls) the pilot pressure control valve 58. The controller 62 includes a microcomputer, a drive circuit, a power supply circuit, and the like. That is, the controller 62 has an arithmetic processing unit including a memory such as a RAM and a ROM, and a CPU, and operates according to a computer program. The input side of the controller 62 is connected to the tilt changeover switch 60, the oil temperature sensor 61, and the pressure sensor 30. The output side of the controller 62 is connected to the pilot pressure control valve 58. Further, power is supplied to the controller 62 from a battery (not shown) serving as a power source mounted on the upper swing body 4.

  The controller 62 receives the traveling pilot pressure Pt detected by the pressure sensor 30, that is, the driving pressure Pt of the direction control valves 23 and 24 by the operation of the traveling operation devices 28 and 29. The controller 62 receives the temperature T of the hydraulic oil tank 15 detected by the oil temperature sensor 61, that is, the oil temperature T of the hydraulic oil tank 15. The controller 62 receives the state of the tilt changeover switch 60, that is, whether the travel mode (selected position) is the low speed mode (low speed position) or the high speed mode (high speed position).

  The controller 62 supplies driving electric power W to the pilot pressure control valve 58 and controls the shifting pilot pressure P acting on the pilot pressure port 46 of the driving devices 32 and 55 for traveling. For example, the controller 62 determines that the driving devices 32 and 55 for traveling are being driven (that is, detects the driving pressure Pt), and the tilt changeover switch 60 has a small motor tilt (high speed, low torque). ), The power W is supplied to the pilot pressure control valve 58.

  As described above, the controller 62 determines whether or not the traveling operation devices 28 and 29 are operated (whether the driving pressure Pt detected by the pressure sensor 30 is equal to or higher than the threshold value Pa) and the selected position of the tilt changeover switch 60. In response, the pilot pressure control valve 58 is controlled. Thereby, the controller 62 controls the motor capacity (motor tilting state) of the driving devices 32 and 55 for traveling. Specifically, the controller 62 has a small capacity (high speed, low torque) when the travel operation devices 28 and 29 are operated when the tilt changeover switch 60 is in the high speed position. Thus, the electric power W is supplied to the pilot pressure control valve 58 (the electromagnetic pilot part 58A). On the other hand, the controller 62 does not supply the electric power W to the pilot pressure control valve 58 (the electromagnetic pilot part 58A) when the tilt changeover switch 60 is at the low speed position. In this case, the hydraulic motors 33 and 56 have a large capacity (low speed, high torque).

  By the way, in the above-mentioned Patent Document 1, the pressure oil from the pilot pump is supplied to one drain port of the two drain ports of the fixed displacement hydraulic motor and discharged from the other drain port. A technique for warming up the hydraulic motor is described. On the other hand, a circuit for communicating these is provided between the speed change pilot line and the drain line of the variable displacement hydraulic motor, and the speed change pilot pressure is supplied from the speed change pilot line to the drain circuit. Thus, it is conceivable to warm up the variable displacement hydraulic motor. However, in this case, if the variable displacement hydraulic motor is shifted, for example, when the variable displacement hydraulic motor is shifted during traveling, the shift pilot pressure is always leaked to the drain line by simply communicating between the shift pilot line and the drain line. As a result, efficiency decreases. In addition to this, the leakage of the shifting pilot pressure may reduce the responsiveness of the shifting control during traveling.

  On the other hand, it is conceivable to add a new sensor to the hydraulic motor in order to perform warm-up control including determination of start / end of warm-up by the controller. In this case, however, the cost increases due to the addition of a new sensor. On the other hand, a configuration that requires an operator's operation to start and end warm-up, for example, a configuration that requires an ON / OFF operation of the warm-up switch, reduces the convenience for the operator. In addition to this, for example, when there is no need to warm up, there is a possibility that warm-up continues without turning off the warm-up switch, and the efficiency may decrease.

  Further, while the hydraulic motor is being driven, pressure oil for driving the hydraulic motor is supplied from the main pipeline, and the pressure oil supplied from the main pipeline is warm hydraulic fluid. For this reason, it is not preferable from the viewpoint of efficiency to perform warm-up by supplying the shifting pilot pressure from the shifting pilot line while driving the hydraulic motor. Furthermore, when the variable displacement hydraulic motor is started while warming up by supplying the shifting pilot pressure, there is a possibility that the drive is started with a small tilt angle. In this case, the driving force of the variable displacement hydraulic motor may be reduced.

  On the other hand, in the embodiment, in order to warm up the traveling hydraulic motors 33 and 56 that are variable displacement hydraulic motors, the traveling drive devices 32 and 55 have a warm-up pilot pipe line 64. Is provided. Hereinafter, the warm-up circuit device 63 for warming up the traveling hydraulic motors 33 and 56 will be described.

  The warm-up circuit device 63 is a hydraulic motor warm-up device. The warm-up circuit device 63 includes a warm-up pilot pipeline 64 in addition to the counter balance valve 49, the drain pipeline 57, the transmission pilot pipeline 59, and the pilot pressure control valve 58 described above. . The warm-up circuit device 63 also includes a controller 62, an oil temperature sensor 61, and a pressure sensor 30. The warm-up pilot pipeline 64 is a pipeline (oil channel) that connects the pilot pressure port 46 and the drain port 54. That is, the warm-up pilot pipeline 64 connects the speed change pilot pipeline 59 and the drain pipeline 57 via the counter balance valve 49.

  In this case, the warm-up pilot pipe line 64 is connected to the counter-balance valve 49 (the warm-up port 49A) at one end and connected to the middle of the shifting pilot pipe 59 at one end. Pilot line 64A, and the other-side warm-up pilot line with one end connected to the counterbalance valve 49 (warm-up port 49B) and the other end connected to the drain port 54 (drain line 57) 64B.

  On the other hand, the counter balance valve 49 is a 6-port 3-position hydraulic pilot type directional control valve. In this case, the counter balance valve 49 includes warm-up ports 49A and 49B serving as center bypass ports. One warm-up port 49A is connected to the other end of the one-side warm-up pilot line 64A. The other warm-up port 49B is connected to one end side of the other warm-up pilot pipeline 64B.

  When the counter balance valve 49 is in the neutral position (a), the warm-up ports 49A and 49B communicate with each other. That is, at the neutral position (a), the pilot pressure port 46 and the drain port 54 communicate with each other by the communication between the one-side warm-up pilot line 64A and the other-side warm-up pilot line 64B. To do. On the other hand, when the counter balance valve 49 is in the drive positions (b) and (c), the warm-up ports 49A and 49B are shut off. That is, at the drive positions (b) and (c), the pilot pressure port 46 and the drain port 54 are shut off by disconnecting the one-side warm-up pilot pipeline 64A and the other-side warm-up pilot pipeline 64B. Is interrupted.

  As described above, the neutral position (a) of the counter balance valve 49 is provided with the oil passage 49 </ b> C that allows the transmission pilot conduit 59 and the drain conduit 57 to communicate with each other through the warm-up pilot conduit 64. Thus, when the hydraulic motors 33 and 56 are stopped, the counter balance valve 49 communicates the speed change pilot line 59 and the drain line 57 via the warm-up pilot line 64. On the other hand, the counter balance valve 49 shuts off the warm-up pilot pipeline 64 when the hydraulic motors 33 and 56 are driven.

  On the other hand, the controller 62 supplies pressure oil (pilot pressure P) to the shifting pilot line 59 through the pilot pressure control valve 58 when it is determined that the hydraulic motors 33 and 56 need to be warmed up. Warm up 33,56. That is, when it is determined that the warm-up is necessary, the controller 62 supplies the warm-up pilot pressure P to the shifting pilot line 59 through the pilot pressure control valve 58. At this time, when the counter balance valve 49 is in the neutral position (a), the pressure oil supplied from the pilot pressure control valve 58 to the shifting pilot line 59 is the pressure oil for warming up (warm-up pressure oil). Thus, it flows from the shifting pilot line 59 to the drain line 57 via the warm-up pilot line 64. Thereby, the pressure oil for warming up passes the hydraulic motors 33 and 56 (the motor casing 34), and can warm up the hydraulic motors 33 and 56.

  Here, the controller 62 determines the start and interruption of warm-up (that is, supply of pressure oil for warm-up through the pilot pressure control valve 58) as follows. For example, the controller 62 determines the start of warm-up by “the temperature Ts of the hydraulic oil detected by the oil temperature sensor 61” and “the degree of operation of the travel operation devices 28 and 29 (total operation count N or total operation time M ) ”. Specifically, the controller 62 detects that the oil temperature Ts at the time of engine start is less than a predetermined value T0, and the travel operation devices 28 and 29 are more than a predetermined number of times NF during a predetermined time t0 from the time of engine start. If not, warm-up is started (determining that warm-up is necessary). Further, the controller 62 interrupts the warm-up when the travel operation devices 28 and 29 are being operated.

  Thus, in the first embodiment, the controller 62 determines whether the hydraulic motors 33 and 56 need to be warmed up based on whether or not both of the following two conditions are satisfied. The first condition is that the temperature Ts detected by the oil temperature sensor 61 when the engine 12 is started is equal to or less than a certain value T0 (or less than a certain value T0). The second condition is that the cumulative number of operations N of the travel operation devices 28 and 29 during the elapse of the predetermined time t0 from the start of the engine 12 is less than the predetermined number NF (or less than the predetermined number NF).

  When it is determined that the warm-up is necessary, the controller 62 supplies the drive power W to the electromagnetic pilot portion 58A of the pilot pressure control valve 58. In this case, the controller 62 is for warm-up so that the pilot pressure P supplied through the pilot pressure control valve 58 becomes smaller than the minimum speed change pilot pressure (minimum driving pressure) P0 necessary for switching the tilt switching valve 51. Drive power W is output. That is, when the hydraulic motors 33 and 56 are warmed up, the pilot pressure P supplied to the shifting pilot line 59 through the pilot pressure control valve 58 is the switching required pressure P0 at which the tilt switching valve 51 switches. Lower pressure (P <P0).

  On the other hand, when the controller 62 determines that the warm-up of the hydraulic motors 33 and 56 is finished, the controller 62 stops supplying the warm-up pressure oil (pilot pressure P) to the speed change pilot pipe line 59. That is, the controller 62 stops the supply of the warm-up drive power W to the electromagnetic pilot portion 58A of the pilot pressure control valve 58. In this case, the controller 62 determines whether or not to end the warm-up when performing the warm-up, “elapsed time tH since the start of the warm-up” and “the travel operation devices 28 and 29. The determination is made based on the degree of operation (total operation count N or total operation time M). Specifically, the controller 62 warms up when a predetermined time tF has elapsed since the start of warming up, or when the traveling operation devices 28 and 29 have been operated more than a predetermined number of times NF from the start of the engine. finish. The warm-up control performed by the controller 62, that is, the control process of the controller 62 shown in FIG. 5 will be described in detail later.

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

  When the operator who has boarded the cab 7 starts the engine 12, the hydraulic pumps 13, 14, and 20 are driven by the engine 12. As a result, the hydraulic oil discharged from the hydraulic pumps 13 and 14 is applied to the traveling hydraulic motors 33 and 29 in accordance with the lever operation and pedal operation of the traveling operation devices 28 and 29 provided in the cab 7 and the working lever operation device. 56, discharging to the swing hydraulic motor, the boom cylinder 5D, the arm cylinder 5E, and the bucket cylinder 5F of the working device 5. As a result, the excavator 1 can perform a traveling operation by the lower traveling body 2, a turning operation by the upper revolving body 4, an excavation work by the work device 5, and the like.

  Here, the controller 62 warms up the driving devices 32 and 55 (hydraulic motors 33 and 56) as necessary when the engine 12 is started. Therefore, the warm-up control process by the controller 62 will be described with reference to FIG. Each step in the flowchart shown in FIG. 5 (and FIGS. 6 to 8 described later) uses the notation “S” (for example, step 1 = “S1”).

  For example, when power supply to the controller 62 is started, the controller 62 starts the control process of FIG. When the controller 62 detects the start of the engine 12 in S1, the controller 62 proceeds to S2. In S2, the controller 62 reads the hydraulic oil temperature TS (hereinafter also referred to as the oil temperature TS) immediately after the engine is started. The oil temperature TS can be detected by the oil temperature sensor 61.

  In subsequent S3, it is determined whether or not the oil temperature Ts read in S2 is equal to or higher than a predetermined value T0. The predetermined value T0 is set as a constant value in the oil temperature range that is less affected by heat shock and response delay. For example, the predetermined value T0 can be set as the lowest temperature (for example, about 0 ° C.) at which the traveling drive devices 32 and 55 do not need to be warmed up. The predetermined value T0 is obtained in advance by experiments, calculations, simulations, etc. so that it can be appropriately determined whether or not warm-up is necessary.

  If “YES” in S3, that is, if it is determined that the oil temperature Ts is equal to or higher than the predetermined value T0, the process proceeds to the warm-up control end process in S4. In S4, if the warm-up control is being executed, the warm-up control is terminated and then the process proceeds to return, and if it is not being warmed up, the process proceeds to return without doing anything. Then, the process returns to the start via the return, and the processes after S1 are repeated.

  On the other hand, if “NO” in S3, that is, if it is determined that the oil temperature Ts is lower than the predetermined value T0, the process proceeds to S5. In S5, an elapsed time tE after the engine start in S1 is read. In subsequent S6, it is determined whether or not the elapsed time tE read in S5 is equal to or longer than the predetermined time t0. The predetermined time t0 can be set as an operation time until a temperature difference that causes a heat shock or a response delay occurs between the hydraulic oil on the upper swing body 4 side and the hydraulic oil on the traveling drive devices 32 and 55 side.

  That is, during the predetermined time t0, the temperature of the hydraulic oil on the upper swing body 4 side is caused by heat shock or the like based on the drive of the hydraulic pumps 13 and 14 and the cylinders 5D, 5E, and 5F of the work device 5 after the engine is started. It is set as a constant value in the range of operating hours expected to rise until the temperature difference is reached. For example, the predetermined time t0 can be set as a time (for example, about 10 minutes) until the temperature of the hydraulic oil rises by about 50 ° C. from the oil temperature TS at the time of engine start. The predetermined time t0 is obtained in advance by experiments, calculations, simulations, or the like so that it is possible to appropriately determine whether or not a temperature difference that causes a heat shock or a response delay occurs.

  If “NO” in S6, that is, if it is determined that the elapsed time tE is less than the predetermined time t0 (tE <t0), the process returns to S5 and repeats the processes after S5. On the other hand, if “YES” in S6, that is, if it is determined that the elapsed time tE is equal to or longer than the predetermined time t0 (tE ≧ t0), the process proceeds to S7. In S7, it is determined whether or not the traveling operation devices 28 and 29 are being operated. This determination can be made based on whether or not the traveling pilot pressure Pt is detected by the pressure sensor 30. More specifically, the controller 62 is operating the traveling operation devices 28 and 29 when the traveling pilot pressure Pt detected by the pressure sensor 30 is larger than a preset threshold Pa (Pt> Pa). Can be determined.

  If “YES” in S7, that is, if it is determined that the travel operation devices 28 and 29 are being operated, the process proceeds to S8. In this case, pressure oil (pressure oil whose temperature has risen) from the hydraulic pumps 13 and 14 is supplied to the hydraulic motors 33 and 56. For this reason, in this case, the process proceeds to the warm-up control interruption process of S8, and if the warm-up control is being executed, the warm-up control is interrupted. That is, in the warm-up control interruption process of S8, the controller 62 supplies the driving power W to the pilot pressure control valve 58 only when the tilt changeover switch 60 is set to the high speed position (motor tilt small tilt). To do. In this case, the controller 62 drives the driving power W such that the pilot pressure P supplied through the pilot pressure control valve 58 becomes larger than the minimum speed change pilot pressure (minimum driving pressure) P0 necessary for switching the tilt switching valve 51. Is output. If the warm-up control interruption process is performed in S8, the process returns to before S5, and the processes after S5 are repeated.

  On the other hand, if “NO” in S7, that is, if it is determined that the travel operation devices 28 and 29 are not being operated, the process proceeds to S9. In S9, the warm-up control time tH, which is the cumulative time during which the warm-up control is performed, and the number of operations N (Pt detection number N) of the travel operation devices 28 and 29 are read. The warm-up control time tH can be, for example, an elapsed time after the determination of YES is first made in S11 and the execution of the warm-up control in S12 is started. Further, the number of operations N can be, for example, the total number of operations from the detection of engine start in S1 to the present. In this case, the number of operations N can be the cumulative number of times that the traveling pilot pressure Pt is detected by the pressure sensor 30, in other words, the cumulative number of times that the traveling pilot pressure Pt is greater than a preset threshold Pa.

  In subsequent S10, it is determined whether or not the warm-up control time tH read in S9 is less than a predetermined time tF. The predetermined time tF is set as a value in a time range in which the oil temperature inside the driving devices 32 and 55 for traveling is predicted to rise to an oil temperature that is less affected by heat shock and response delay due to the warm-up control. For example, the predetermined time tF is supplied with driving oil (warm-up pressure oil) for warming up from the pilot pressure control valve 58 to the shifting pilot line 59 to drive the driving devices 32, 55 (hydraulic motors 33, 56) until the internal oil temperature rises to about 0 ° C. (for example, about 10 minutes). The predetermined time tF can be variably adjusted based on the oil temperature Ts at the time of starting the engine, the outside air temperature, etc. read in S2. For example, when the outside air temperature is extremely low such as −20 ° C., tF can be set to about 20 minutes, for example. In any case, the predetermined time tF is obtained in advance by experiment, calculation, simulation, or the like so that the end of the warm-up control can be appropriately determined.

  If “YES” in S10, that is, if it is determined that the warm-up control time tH is less than the predetermined time tF (tH <tF), the process proceeds to S11. In S11, it is determined whether or not the operation number N of the travel operation devices 28 and 29 read in S9 is less than a predetermined number NF. The predetermined number of times NF is a value in the range of the number of operations that is predicted to increase to an oil temperature that is less affected by heat shock and response delay due to the drive of the hydraulic motors 33 and 56. Set. For example, the predetermined number of times NF can be a time (for example, about 5 times) until the oil temperature inside the driving devices 32 and 55 for traveling rises to about 0 ° C. by driving the hydraulic motors 33 and 56. Further, the predetermined number of times NF may be variably adjusted based on the oil temperature Ts at the time of starting the engine, the outside air temperature, etc. read in S2. In any case, the predetermined number of times NF is determined by experiments, calculations, simulations, etc. in advance so that the determination of the end of the warm-up control (and the determination of whether or not to start the warm-up control) can be performed appropriately. I ask for it.

  If “YES” in S11, that is, if it is determined that the number N of operations of the travel operation devices 28 and 29 is less than the predetermined number NF (N <NF), the process proceeds to S12. In S12, warm-up process control is performed. That is, the controller 62 applies the shift pilot pressure P to the pilot pressure port 46 of the driving devices 32 and 55 for traveling by supplying the driving power W to the pilot pressure control valve 58. In this case, the controller 62 drives the driving power W so that the pilot pressure P supplied through the pilot pressure control valve 58 becomes smaller than the minimum speed change pilot pressure (minimum driving pressure) P0 necessary for switching the tilt switching valve 51. Is output. That is, the driving power W at the time of warming up is smaller than the driving power W at the time of switching the tilt switching valve 51. If the warm-up control execution process is performed in S11, the process returns to before S7, and the processes after S7 are repeated.

  On the other hand, if “NO” in S10, that is, it is determined that the warm-up control time tH is equal to or longer than the predetermined time tF (tH ≧ tF), and “NO” in S11, that is, the operating devices 28 and 29 for traveling. When it is determined that the number of operations N is equal to or greater than the predetermined number NF (N ≧ NF), the process proceeds to S4. In S4, warm-up control end processing is performed. That is, in this case, if the warm-up control execution process is being performed, the control is terminated. Specifically, the controller 62 detects the operation (driving pressure Pt) of the travel operation devices 28 and 29, and the tilt changeover switch 60 is set to the high speed position (motor tilt small tilt). Only, the driving power W is supplied to the pilot pressure control valve 58. In this case, the controller 62 drives the driving power W such that the pilot pressure P supplied through the pilot pressure control valve 58 becomes larger than the minimum speed change pilot pressure (minimum driving pressure) P0 necessary for switching the tilt switching valve 51. Is output.

  As shown in FIG. 5, in the first embodiment, when the oil temperature Ts at the time of engine start is less than a predetermined value T0 and the predetermined time t0 has elapsed since the engine start, When the operation number N of 29 is not operated more than the predetermined number of times NF, the warm-up control of the driving devices 32 and 55 (hydraulic motors 33 and 56) is performed. That is, the oil temperature of the hydraulic oil in the hydraulic oil tank 15 of the upper swing body 4 rises as time elapses after the engine is started, whereas the driving devices 32 and 55 for traveling of the lower traveling body 2 and the internal hydraulic oil Is determined to remain at a low temperature before the engine is started, warm-up control of the driving devices 32 and 55 for traveling is performed.

  This warm-up control is performed when the controller 62 supplies electric power W to the pilot pressure control valve 58 when the hydraulic motors 33 and 56 are stopped (the travel operation devices 28 and 29 are not operated). Is called. In other words, the controller 62 applies the speed change pilot pressure P (<P0) (for warm-up) to the pilot pressure port 46 of the travel drive devices 32, 55 through the pilot pressure control valve 58, thereby causing the hydraulic motors 33, 56 warm-up control is performed.

  The hydraulic fluid that has flowed into the pilot pressure port 46, that is, the hydraulic fluid that has been warmed in the hydraulic oil tank 15, passes through the one-side warm-up pilot line 64A, the counter balance valve 49, and the other-side warm-up pilot line 64B. It passes through, is discharged from the drain port 54, and returns to the hydraulic oil tank 15 again. At this time, since the hydraulic oil passes through the case (motor casing 34) that houses the brake valve 44 and the hydraulic motors 33 and 56, the hydraulic oil and components inside the travel drive devices 32 and 55 are warmed and warmed up. .

  Here, when the travel operation devices 28 and 29 are operated with the intention of traveling during the warm-up control, the warm-up control of the hydraulic motors 33 and 56 is interrupted. That is, when the driving devices 32 and 55 for driving are driven, the control for applying the speed change pilot pressure P for warming up to the pilot pressure port 46 of the driving devices 32 and 55 for driving is interrupted. In this case, the controller 62 detects the operation (driving pressure Pt) of the travel operation devices 28 and 29, and only when the tilt changeover switch 60 is set to the high speed position (motor tilt small tilt). The driving power W is supplied to the pilot pressure control valve 58. Further, when the travel drive devices 32 and 55 are driven, the spool of the counter balance valve 49 moves to the drive positions (b) and (c), so that the pilot pressure port 46 and the drain port 54 are shut off. .

  When the predetermined time tF elapses from the start of the warm-up control of the hydraulic motors 33 and 56, or when the travel operation devices 28 and 29 are operated a predetermined number of times NF or more, the warm-up control of the hydraulic motors 33 and 56 is terminated. That is, when it is determined that the oil temperature inside the driving devices 32 and 55 has increased to an oil temperature that is less affected by heat shock and response delay, the warm-up control of the hydraulic motors 33 and 56 is terminated. That is, in this case, the control for causing the transmission pilot pressure P to act on the pilot pressure port 46 of the travel drive devices 32 and 55 when the hydraulic motors 33 and 56 are stopped is not performed.

  As described above, the warm-up circuit device 63 according to the embodiment has both the motor tilt function and the motor warm-up function, and even if the motor warm-up function is added, other functions and conveniences are impaired. Can be suppressed. In the embodiment, it is not necessary to add a new control valve or piping for adding a warm-up function. For this reason, an increase in cost can be suppressed. In the embodiment, the transmission pilot (pilot pressure port 46) and the motor drain (drain port 54) are communicated only when the hydraulic motors 33 and 56 are stopped. This prevents the shifting pilot pressure (ie, hydraulic fluid) from leaking to the drain side during normal travel. For this reason, it is efficient, and it is possible to prevent the leak from adversely affecting the shift control response during traveling.

  Furthermore, since it is not necessary to add a new sensor to the hydraulic motors 33 and 56, an increase in cost can be suppressed also from this aspect. Further, it is not necessary for the operator to operate the switch for warming up, and convenience can be improved. Moreover, since the warm-up control is terminated when the oil temperature of the hydraulic motors 33 and 56 rises, this is also efficient from this aspect. Further, during the traveling, the warm-up control is interrupted, and the warm-up is performed by the main oil passages for driving the hydraulic motors 33, 56 (that is, the traveling supply / discharge conduits 25A, 25B, 26A, 26B). For this reason, this aspect is also efficient. Further, the shift pilot pressure P (for warm-up) when the warm-up control is being performed is set to be less than the required switching pressure P0 of the tilt switching valve 51. For this reason, even if the hydraulic motors 33 and 56 are driven in a state where the transmission pilot pressure P is applied, the motor does not tilt slightly, and a sufficient driving force at the start of traveling can be ensured.

  As described above, according to the first embodiment, when the hydraulic motors 33 and 56 are stopped, the counter-balance valve 49 causes the speed change pilot line 59 and the drain line 57 to warm up. Communication is made via a pilot line 64. In this state, when the pressure oil from the pilot hydraulic pump 20 is supplied to the shifting pilot line 59 through the pilot pressure control valve 58, the pressure oil is used as pressure oil for warming up (warm-up pressure oil). Thus, it flows from the shifting pilot line 59 to the drain line 57 via the warm-up pilot line 64. At this time, the pressure oil (warm-up pressure oil) passes through the case (motor casing 34) of the hydraulic motors 33 and 56, whereby the hydraulic motors 33 and 56 can be warmed up. In this case, since it is not necessary to add a new control valve for warming up and a dedicated pipe line as in Patent Document 1, it is possible to suppress a complicated structure and an increase in cost.

  On the other hand, the counter balance valve 49 blocks the warm-up pilot pipe line 64 when the hydraulic motors 33 and 56 are driven. Thereby, when the hydraulic motors 33 and 56 are driven, even if the pressure oil from the pilot hydraulic pump 20 is supplied to the speed change pilot line 59 through the pilot pressure control valve 58, the pressure oil is changed to the speed change pilot. Supply from the pipeline 59 to the drain pipeline 57 via the warm-up pilot pipeline 64 is prevented. For this reason, it is possible to prevent the shifting pilot pressure P for shifting the hydraulic motors 33 and 56 from leaking to the drain conduit 57 when the hydraulic motors 33 and 56 are being driven. As a result, it is possible to suppress a decrease in efficiency and a decrease in the response of shifting. In addition, when the hydraulic motors 33 and 56 are being driven, the pressure oil for driving the hydraulic motors 33 and 56 is supplied to the hydraulic motors 33 and 56, so that warm-up is performed. , Warming up can be performed efficiently.

  According to the first embodiment, the controller 62 warms up the hydraulic motors 33 and 56 based on “the oil temperature Ts at the time of starting the engine” and “the number N of operations of the travel operation devices 28 and 29”. Whether or not is necessary. Specifically, when the oil temperature Ts is less than the predetermined value T0 and the traveling operation devices 28 and 29 are not operated more than the predetermined number of times NF during the elapse of the predetermined time t0 from the engine start, Judge that warm-up is necessary. When the controller 62 determines that the hydraulic motors 33 and 56 need to be warmed up, the pilot pressure P (<P0) serving as warming pressure oil is supplied to the shifting pilot line 59 through the pilot pressure control valve 58. Is supplied, the hydraulic motors 33 and 56 are warmed up.

  Thus, the controller 62 can automatically start warming up. That is, when the warm-up is started, an operator's operation (for example, an operation for turning on the warm-up switch) becomes unnecessary, and the convenience for the operator can be improved. Moreover, the pressure sensor 30 that detects the operation of the oil temperature sensor 61 and the travel operation devices 28 and 29 may be, for example, those originally provided. For this reason, it is not necessary to add a new sensor, and cost can be suppressed also from this aspect.

  According to the first embodiment, the controller 62 is based on the “elapsed time tH from the start of warming-up of the hydraulic motors 33 and 56” and the “number of operations N of the travel operation devices 28 and 29”. Thus, it is determined whether or not the warm-up of the hydraulic motors 33 and 56 is finished. Specifically, the controller 62 warms up when a predetermined time tF has elapsed since the start of warm-up, or when the travel operation devices 28 and 29 have been operated more than a predetermined number of times NF since the engine start. Is determined to end. When the controller 62 determines that the warm-up of the hydraulic motors 33 and 56 is to be finished, the controller 62 supplies the pilot pressure P, which serves as warm-up pressure oil, to the transmission pilot line 59 through the pilot pressure control valve 58. To stop. Thereby, warming-up of the hydraulic motors 33 and 56 can be stopped.

  Thus, the controller 62 can automatically end (stop) the warm-up. That is, when the warm-up is finished, an operator's operation (for example, an operation for turning off the warm-up switch) becomes unnecessary, and from this aspect, the convenience for the operator can be improved. In addition, when there is no need for warm-up, it is possible to prevent the warm-up from continuing without turning off the warm-up switch. Thereby, the fall of efficiency can be controlled also from this surface.

  According to the first embodiment, when the hydraulic motors 33 and 56 are warmed up, the pilot pressure P supplied to the shifting pilot pipe 59 through the pilot pressure control valve 58 is the tilt switching valve 51. The pressure is lower than the required switching pressure P0 at which the For this reason, when the hydraulic motors 33 and 56 are warmed up, the tilt angle of the hydraulic motors 33 and 56 can be maintained at a large inclination. Thereby, even if the hydraulic motors 33 and 56 are driven while the hydraulic motors 33 and 56 are warmed up, the driving force of the hydraulic motors 33 and 56 can be secured.

  According to the first embodiment, an oil passage 49 </ b> C is provided in the neutral position (a) of the counter balance valve 49 to communicate the speed change pilot pipe 59 and the drain pipe 57 through the warm-up pilot pipe 64. It has been. For this reason, when the hydraulic motors 33 and 56 are stopped, the counter balance valve 49 causes the transmission pilot line 59 and the drain line 57 to communicate with each other, and the hydraulic motors 33 and 56 are driven. Sometimes the transmission pilot line 59 and the drain line 57 can be shut off stably.

  Next, FIG. 6 shows a second embodiment. The second embodiment is characterized by determining whether or not to start warm-up based on the operation time of the travel operation device from when the engine starts until the oil temperature rises to a constant value. There is a configuration in which it is determined whether or not to end the warm-up based on time. In the second embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  The controller 62 of the second embodiment determines whether or not the hydraulic motors 33 and 56 need to be warmed up based on whether or not both of the following two conditions are satisfied. The first condition is whether or not the temperature Ts detected by the oil temperature sensor 61 when the engine 12 is started is equal to or less than a certain value T0 (or less than a certain value T0). The second condition is that the cumulative operation time M of the travel operation devices 28 and 29 during the time when the oil temperature T rises to the predetermined temperature TH or higher after the engine 12 is started is less than the predetermined time MF (or less than the predetermined time MF). Whether there is.

  Further, in the second embodiment, the controller 62 determines whether or not to end the warm-up when performing the warm-up, “elapsed time tH from the start of the warm-up” and “running” Determination based on the total operation time M of the operation devices 28 and 29 for use.

  FIG. 6 shows a control process performed by the controller 62. The control process of FIG. 6 is used in the second embodiment instead of the control process of FIG. 5 of the first embodiment described above. Note that S1-4, 7, 8, 10, and 12 in the control process of FIG. 6 are the same as the control processes of S1-4, 7, 8, 10, and 12 in FIG. Hereinafter, the process of S21-24 in FIG. 6 will be described.

  In the second embodiment, if “NO” is determined in S3, the process proceeds to S21. In S21, the temperature of the hydraulic oil in the hydraulic oil tank 15, that is, the oil temperature T detected by the oil temperature sensor 61 is read. In subsequent S22, it is determined whether or not the oil temperature T read in S21 is equal to or higher than a predetermined temperature TH. The predetermined temperature TH can be set as a temperature at which heat shock or response delay may occur when hydraulic oil on the upper swing body 4 side is supplied to the hydraulic motors 33 and 56.

  That is, the predetermined temperature TH rises when the oil temperature Ts at the time of starting the engine rises based on the drive of the hydraulic pumps 13 and 14 of the upper swing body 4 and the cylinders 5D, 5E, and 5F of the work device 5, and the raised hydraulic oil When it flows into the low-temperature hydraulic motors 33 and 56, it is set as a constant value in a temperature range in which heat shock or the like may occur. For example, the predetermined temperature TH can be set as 50 ° C. or Ts + 50 ° C. The predetermined temperature TH is obtained in advance by experiments, calculations, simulations, or the like so that it can be appropriately determined whether or not the temperature (temperature difference) at which there is a risk of heat shock or delay in response has been reached.

  If “NO” in S21, that is, if it is determined that the oil temperature T is lower than the predetermined temperature TH (T <TH), the process returns to before S21, and the processes after S21 are repeated. On the other hand, if “YES” in S21, that is, if it is determined that the oil temperature Ts is equal to or higher than the predetermined temperature TH (T ≧ TH), the process proceeds to S7.

  If “NO” is determined in S7, the process proceeds to S23. In S23, the warm-up control time tH, which is the cumulative time during which the warm-up control is performed, and the cumulative operation time M (Pt detection time M) of the travel operation devices 28 and 29 are read. The accumulated operation time M can be, for example, an accumulated time during which the traveling operation devices 28 and 29 have been operated until the present time is detected in S1. In this case, the cumulative operation time M can be a cumulative time when the traveling pilot pressure Pt is detected by the pressure sensor 30, in other words, a cumulative time when the traveling pilot pressure Pt becomes larger than a preset threshold Pa.

  If “YES” is determined in S10, the process proceeds to S24. In S24, it is determined whether or not the cumulative operation time M of the travel operation devices 28 and 29 read in S23 is less than a predetermined time MF. The predetermined time MF is a value within a range of a cumulative operation time in which the oil temperature inside the driving devices 32 and 55 for traveling is predicted to rise to an oil temperature that is less affected by heat shock and response delay by driving the hydraulic motors 33 and 56. Set as. For example, the predetermined time MF can be a time (for example, about 10 minutes) until the oil temperature inside the driving devices 32 and 55 for traveling rises to about 0 ° C. by driving the hydraulic motors 33 and 56. Further, the predetermined time MF can be variably adjusted based on the oil temperature Ts at the time of engine start, the outside air temperature, etc. read in S2. In any case, the predetermined time MF is determined in advance by experiments, calculations, simulations, etc. so that the determination of the end of the warm-up control (and the determination of whether the warm-up control should be started) can be appropriately performed. I ask for it.

  If “YES” in S24, that is, if it is determined that the cumulative operation time M of the travel operation devices 28 and 29 is less than the predetermined time MF (M <MF), the process proceeds to S12. On the other hand, if “NO” in S24, that is, if it is determined that the cumulative operation time M of the travel operation devices 28 and 29 is equal to or longer than the predetermined time MF (M ≧ MF), the process proceeds to S4.

  In such a second embodiment, while the oil temperature Ts at the time of starting the engine is lower than the predetermined value T0 and the temperature of the hydraulic oil rises to the predetermined temperature TH, the traveling operation devices 28 and 29 are When the MF has not been operated for a predetermined time MF or longer, the warm-up control of the driving devices 32 and 55 (hydraulic motors 33 and 56) is performed. Further, when the travel operation devices 28 and 29 are operated with the intention of traveling during the warm-up control, the warm-up control of the hydraulic motors 33 and 56 is interrupted. Then, when the predetermined time tF has elapsed from the start of the warm-up control of the hydraulic motors 33 and 56 or when the travel operation devices 28 and 29 are operated for the predetermined time MF or longer, the warm-up control of the hydraulic motors 33 and 56 is terminated.

  In the second embodiment, the control process of FIG. 6 as described above is performed by the controller 62, and the basic operation is not different from that of the first embodiment described above. That is, in the second embodiment, as in the first embodiment, the hydraulic motors 33 and 56 can be warmed up, and the structure is complicated, the cost is increased, the efficiency is decreased, and the speed is changed. It is possible to suppress a decrease in responsiveness.

  In the first embodiment (FIG. 5), when “NO” is determined in S3, the process proceeds to S5 and S6, and an example is described in which the elapsed time tE after engine start is determined. Explained. However, the present invention is not limited to this, and for example, as in the first modification shown in FIG. 7, the processing of S31 and S32 may be provided between S3 and S5. In S31, the operation number N (Pt detection number N) of the operation devices for traveling 28 and 29 is read. In subsequent S32, it is determined whether or not the number of operations N read in S31 is less than a predetermined number of times NF. The predetermined number of times NF is the same as the predetermined number of times NF in S11. If “YES” is determined in S32, the process proceeds to S5, and if “NO” is determined in S32, the process proceeds to S4.

  In the second embodiment (FIG. 6), if “NO” is determined in S3, the process proceeds to S21 and S22, and an example in which the oil temperature T detected after the engine is started is determined as an example. explained. However, the present invention is not limited to this, and, for example, the processes of S41 and S42 may be provided between S3 and S21 as in the second modification shown in FIG. In S41, the cumulative operation time M (Pt detection time M) of the travel operation devices 28 and 29 is read. In subsequent S42, it is determined whether or not the cumulative operation time M read in S41 is less than a predetermined time MF. The predetermined time MF is the same as the predetermined time MF in S24. If “YES” is determined in S42, the process proceeds to S21. If “NO” is determined in S42, the process proceeds to S4.

  In the first embodiment, a case has been described as an example in which a warm-up start / end determination is made using the cumulative number of operations N of the travel operation devices 28 and 29. However, the present invention is not limited to this. For example, the start / end of warm-up may be determined using the cumulative operation time M of the travel operation devices 28 and 29. In the first embodiment, the start of warm-up is determined based on the cumulative number of operations N of the travel operation devices 28 and 29 during the elapse of a predetermined time t0 from the start of the engine 12. Was described as an example. However, the present invention is not limited to this. For example, the determination may be made based on the cumulative number N of operations of the travel operation devices 28 and 29 while the oil temperature T rises to the predetermined temperature TH after the engine 12 is started.

  In the second embodiment, the case where the warm-up start / end is determined using the accumulated operation time M of the travel operation devices 28 and 29 has been described as an example. However, the present invention is not limited to this. For example, the start / end of warm-up may be determined using the cumulative number N of operations of the travel operation devices 28 and 29. In the second embodiment, the start of warm-up is determined based on the cumulative operation time M of the travel operation devices 28 and 29 while the oil temperature T rises to the predetermined temperature TH from the start of the engine 12. The case where the configuration is adopted has been described as an example. However, the present invention is not limited to this. For example, the determination may be made based on the cumulative operation time M of the travel operation devices 28 and 29 during the elapse of a predetermined time t0 from the start of the engine 12.

  In the first embodiment, the case where the engine is warmed up when the engine is started by detecting the engine start in S1 has been described as an example. In other words, in the first embodiment, the case has been described as an example in which it is determined whether or not to warm up based on the oil temperature Ts at the time of engine start in S3. However, the present invention is not limited to this. For example, the engine may be warmed up as needed during the work without using the engine starting condition as a condition. That is, during work in a cold region, for example, when work (for example, driving of the working device, turning driving) is continued only on the upper turning body side while the vehicle is stopped for a long time, the hydraulic oil of the driving device for traveling is used. Temperature drops.

  In such a case, the temperature difference between the temperature of the hydraulic oil on the upper swing body side and the temperature of the hydraulic oil on the travel drive device side may be a temperature difference at which a heat shock or the like occurs. Therefore, the controller measures, for example, the time (cumulative time) during which the driving device for driving (hydraulic motor) is not driven during the work, and from this time until the temperature difference at which heat shock or the like occurs is reached. Determine whether the temperature of the device has dropped. The controller may be configured to warm up when it is determined that the temperature has decreased to a temperature at which heat shock or the like occurs. The same applies to the second embodiment and each modification.

  In the first embodiment, the case where the hydraulic motors 33 and 56 as variable displacement hydraulic motors are configured by axial piston swash plate hydraulic motors has been described as an example. However, the present invention is not limited to this, and other types of variable displacement hydraulic motors such as a slant axis hydraulic motor and a radial piston hydraulic motor may be used as the hydraulic motor. The same applies to the second embodiment and each modification.

  In each embodiment and each modification, the traveling hydraulic motor for driving the drive wheels 2B of the crawler belt 4D has been described as an example of the variable displacement hydraulic motor. That is, in each embodiment and each modified example, the traveling hydraulic drive device for traveling the lower traveling body 2 has been described as an example of the hydraulic drive device. However, the present invention is not limited to this, and the variable displacement hydraulic motor may be a hydraulic motor that drives a drive target other than the drive wheels 2B. That is, the hydraulic drive device is not limited to a traveling hydraulic drive device for construction machines, and can be widely applied as, for example, various hydraulic drive devices incorporated in industrial machines and general machines.

  Furthermore, each embodiment is an exemplification, and it is needless to say that partial replacement or combination of configurations shown in different embodiments is possible. In each embodiment and each modification, the oil temperature sensor 61 is installed in the hydraulic oil tank 15. For example, the hydraulic pumps 13 and 14, the first discharge pipe 16, the return pipe 17, and the second discharge pipe are used. It may be installed on the road 18. Further, the driving operation is detected by detecting the driving pressure Pt by the operation of the driving lever / pedal operating devices 28 and 29 by the pressure sensor 30, but the present invention is not limited to this. For example, the driving lever / pedal operating device is used. A driving operation may be detected by a detection signal from the sensor that electrically detects the displacement of 28 and 29.

1 Excavator (construction machine)
11 Hydraulic circuit (hydraulic drive)
13 First hydraulic pump (hydraulic power source, hydraulic pump)
14 Second hydraulic pump (hydraulic power source, hydraulic pump)
15 Hydraulic oil tank (hydraulic power source, tank)
20 Pilot hydraulic pump (pilot pump)
23 Directional control valve for left travel (directional control valve)
24 Directional control valve for left travel (directional control valve)
25A, 25B Left supply / discharge line (supply / discharge path)
26A, 26B Right supply / discharge line (supply / discharge path)
28 Left travel lever / pedal operating device (operating device)
29 Left-running lever / pedal operating device (operating device)
33 Left running hydraulic motor (variable displacement hydraulic motor)
40 Swash plate (capacity variable part)
43 Tilt actuator (capacity variable actuator)
49 Counterbalance valve 49C Oil passage 51 Tilt switching valve (capacity control valve)
56 Hydraulic motor for right travel (variable displacement hydraulic motor)
57 Drain line 58 Pilot pressure control valve 59 Shifting pilot line 61 Oil temperature sensor 62 Controller 64 Warm-up pilot line

Claims (5)

A variable displacement hydraulic motor having a variable displacement portion and driven to rotate by pressure oil from a hydraulic source;
A direction control valve provided in the middle of a pair of supply / discharge passages connecting the variable displacement hydraulic motor to a hydraulic source, and for switching the direction of pressure oil supplied to and discharged from the hydraulic source to the variable displacement hydraulic motor;
A counter balance valve provided between the direction control valve and the variable displacement hydraulic motor and provided in the middle of the pair of supply / discharge passages;
A variable capacity actuator that drives a variable capacity section of the variable capacity hydraulic motor to change the motor capacity;
A capacity control valve for switching the pressure oil supplied to the capacity variable actuator;
A pilot pressure control valve for controlling a pilot pressure from a pilot pump to switch the capacity control valve;
A pilot line for speed change that is provided between the pilot pressure control valve and the capacity control valve and supplies pilot pressure from the pilot pressure control valve to the capacity control valve;
A hydraulic drive device comprising: a drain line for discharging drain from the variable displacement hydraulic motor to a tank constituting the hydraulic source;
A warm-up pilot line connected between the speed change pilot line and the drain line via the counter balance valve;
The counter balance valve communicates the speed change pilot line and the drain line via the warm-up pilot line when the variable capacity type hydraulic motor is stopped, A hydraulic drive device characterized in that when the hydraulic motor is driven, the warm-up pilot pipeline is cut off. A controller for controlling the pilot pressure control valve;
An oil temperature sensor connected to the controller and detecting the temperature of the hydraulic oil of the hydraulic source;
The controller is for switching whether the temperature detected by the oil temperature sensor when the engine for driving the hydraulic pump constituting the hydraulic power source is a predetermined value or less and switching the direction control valve. When it is determined that the variable displacement hydraulic motor needs to be warmed up based on one of the number of operation times and the operation time of the operating device, the pilot line for shifting is connected to the shifting pilot line through the pilot pressure control valve. 2. The hydraulic drive apparatus according to claim 1, wherein the variable displacement hydraulic motor is warmed up by supplying a pilot pressure.   The controller starts warming up the variable displacement hydraulic motor to determine whether or not to end warming up of the variable displacement hydraulic motor when warming up the variable displacement hydraulic motor. The hydraulic drive device according to claim 2, wherein the determination is made on the basis of an elapsed time from the operation time, and one of an operation count and an operation time of the operation device.   When the variable displacement hydraulic motor is warming up, the pilot pressure supplied to the shifting pilot line through the pilot pressure control valve is lower than the switching required pressure at which the displacement control valve switches. The hydraulic drive device according to claim 1, wherein   2. The oil passage that connects the speed change pilot line and the drain line through the warm-up pilot line is provided at a neutral position of the counter balance valve. Hydraulic drive device.

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