JP2009133493A - Working fluid cooling control system for construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a working fluid cooling control system for a construction machine, capable of preventing temperature rise of working fluid by increasing cooling performance prior to temperature rise of the working fluid, reducing failure of hydraulic devices, increasing their service life, and eliminating worsening of noise or deterioration of the fuel consumption ratio. <P>SOLUTION: A controller 100 takes input of signals from a travel motor speed pickup 101, a pressure sensor 102, a signal intake line 103a for an option selecting switch 103, and a temperature sensor 104, performs prescribed computation processes, and controls proportional solenoid valves 105 and 106, so that its control pressure is compared with command pressure of positive control at shuttle valves 109 and 110 for the high pressure side to be introduced to tilting control mechanisms 13 and 14. Under an operation pattern where temperature of working fluid rises, the minimum tilting angle of hydraulic pumps 11 and 12 is increased to increase average flow of hydraulic oil passing an oil cooler 40 so as to increase average heat radiation quantity, and lower the equilibrium temperature of working fluid. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a construction machine including a variable displacement hydraulic pump, a plurality of driven bodies driven by the hydraulic pump, and a heat exchanger for cooling a working fluid (working oil) that is a driving medium. The present invention relates to a working fluid cooling control system.

  In a conventional construction machine, particularly a construction machine such as a hydraulic excavator, a cooling system including a heat exchanger that is a cooler of hydraulic oil so that a heat balance of a prime mover, a hydraulic system, and the like is established based on a standard operation by a bucket The specifications have been optimized. In this case, stricter conditions than standard work such as continuous operation of high-load work compared to standard work, operation in a place where the ambient temperature is very high such as in a tunnel, operation in a state where the construction machine has deteriorated, etc. In the operating state, the heat balance is deteriorated, the temperature of the hydraulic system rises, and the life of the hydraulic equipment is adversely affected.

  However, if the cooling system specifications are optimized so that the heat balance is established in advance under severe conditions compared to standard work, such as continuous operation of high-load work, overspec for most standard work during general use Besides, it is uneconomical. In addition, when the capacity of the heat exchanger is increased, the entire cooling system becomes larger, leading to increased costs and larger construction machines, and noise needs to be increased due to the need to increase the cooling air volume. Occurs.

  In order to solve such a problem, Japanese Patent Application Laid-Open No. 2000-110560 discloses a case in which operation is performed under severe conditions compared to standard work while suppressing noise during standard work by variably controlling the rotation speed of the cooling fan. Discloses a technique for increasing the heat dissipation of the cooler.

  In the utility model registration No. 2565113, in a working machine in which a cooling fan is rotated by an operator's manual operation when the operation lever is neutral (no operation state) and the hydraulic oil is cooled by a cooler, the operation lever is neutral. And a technique for maximizing the amount of heat dissipated by the cooler by maximizing the capacity of the variable displacement hydraulic pump by detecting the manual operation of the operator and increasing the flow rate of hydraulic oil passing through the cooler.

JP 2000-110560 A Utility Model Registration No. 2565113

  However, each of the above prior arts basically lowers the oil temperature raised by the cooler after the oil temperature of the hydraulic oil has risen, and the influence of the rise in the oil temperature is unavoidable temporarily. It is. For this reason, the deterioration of the seal parts due to the rise in the oil temperature and the increase in wear of the sliding part due to the lower viscosity of the hydraulic oil occur, resulting in problems of failure of the hydraulic equipment and a decrease in the service life.

  Moreover, in the prior art described in Japanese Patent Application Laid-Open No. 2000-110560, the cooling capacity is improved by increasing the air volume, and it is constant when continuously operating under severe conditions compared to standard work. It is inevitable that noise will worsen.

  In the prior art described in Utility Model Registration No. 2565113, the displacement of the variable displacement hydraulic pump is switched to the maximum when the operation lever is in the neutral position (no operation state), and the pressure loss increases in the no operation state. There are also problems such as deterioration of fuel consumption due to fuel and increase in calorific value. In addition, when the operator inadvertently operates the operation lever without switching the cooler to the non-use state, the start-up is performed in a state where the capacity of the hydraulic pump is switched to the maximum. Furthermore, the cooler is switched to a use state by an operator's manual operation, and there is a problem in usability (operability).

  The object of the present invention is to prevent the temperature of the working fluid from rising by improving the cooling performance before the temperature of the working fluid rises. It is an object to provide a working fluid cooling control system for a construction machine that does not cause a problem of deterioration.

  (1) In order to achieve the above object, the present invention provides a variable displacement hydraulic pump, a plurality of driven bodies driven by the hydraulic pump, and a heat exchanger for cooling a working fluid as a driving medium. In a working fluid cooling control system for a construction machine that reduces the capacity of the hydraulic pump to a preset minimum capacity when the plurality of driven bodies are not operated, the operation related to the plurality of driven bodies Of the patterns, a first detection means for detecting an operation pattern in which the temperature of the working fluid rises, and a minimum capacity of the hydraulic pump is increased based on the operation pattern detected by the first detection means, and the heat exchanger is Pump flow rate increasing means for increasing the average flow rate of the working fluid passing therethrough is provided.

  As described above, the first detecting means and the pump flow rate increasing means are provided to detect the operation pattern in which the temperature of the working fluid rises, thereby increasing the minimum capacity of the hydraulic pump and increasing the average flow rate of the working fluid passing through the heat exchanger. To increase the average heat dissipation of the heat exchanger (increase the cooling performance) and lower the equilibrium temperature of the working fluid in advance (before the working fluid temperature rises) As a result, it is possible to prevent the temperature of the working fluid from rising, thereby reducing the failure of the hydraulic equipment and improving the service life. In addition, by increasing the minimum capacity of the hydraulic pump and increasing the average flow rate of the working fluid passing through the heat exchanger, the cooling performance is improved, so noise deterioration does not occur and fuel consumption deterioration is minimized. Can do.

  (2) In the above (1), the first detection means detects an operation state of a driven body having a high load frequency among the plurality of driven bodies as an operation pattern in which the temperature of the working fluid rises.

  Thus, for example, when an operation pattern in which the temperature of the working fluid rises, such as traveling, is detected, it becomes possible to improve the cooling performance in advance.

  (3) In the above (2), the first detection unit detects an operation signal of the operation unit of the driven body as the operation state of the driven body having a high load frequency.

  As a result, for example, when the operation pattern in which the temperature of the working fluid rises, such as when the travel operation means is fully operated, it is possible to detect this and improve the cooling performance in advance.

  (4) In the above (2), the first detection means detects a driving speed of the driven body as an operation state of the driven body having a high load frequency.

  As a result, when an operation pattern in which the temperature of the working fluid rises, such as high speed running, it is possible to detect this and improve the cooling performance in advance.

  (5) In the above (1), the first detection means detects an operation mode having a high load frequency among operation modes related to the plurality of driven bodies as an operation pattern in which the temperature of the working fluid rises. To do.

  As a result, when an operation pattern in which the temperature of the working fluid rises, such as an operation mode in which a crusher is used, it is possible to detect this and improve the cooling performance in advance.

  (6) In the above (5), the construction machine further includes a selection unit that selects an operation mode using an attachment such as a crusher and another operation mode, and the first detection unit has a high load frequency. The operation mode using the crusher is detected as the operation mode.

  Thus, when the operation mode using the crusher is entered as an operation pattern in which the temperature of the working fluid rises, this can be detected and the cooling performance can be improved in advance.

  (7) Further, in the above (1), the apparatus further comprises second detection means for detecting the temperature of the working fluid, wherein the pump flow rate increase means includes the operation pattern detected by the first detection means and the second detection means. The minimum capacity of the hydraulic pump is increased based on the temperature of the working fluid detected by.

  In this way, when the operating fluid temperature does not rise, the cooling performance of the heat exchanger is increased and increased even if the operating fluid temperature increases due to deterioration of the surrounding environment. The temperature of the working fluid can be lowered.

  (8) In the above (7), the pump flow rate increasing means is a means for calculating a first minimum capacity based on an operation pattern detected by the first detecting means, and a temperature of the working fluid detected by the second detecting means. Means for calculating a second minimum capacity based on the above, means for selecting the larger of the first minimum capacity and the second minimum capacity, and means for changing the minimum capacity of the hydraulic pump based on the selected minimum capacity; Have

  This improves the cooling performance of the heat exchanger before the temperature of the working fluid rises, prevents the temperature of the working fluid from rising, and deteriorates the surrounding environment when the operating fluid temperature does not rise. Thus, even if the temperature of the working fluid has risen, the cooling performance of the heat exchanger can be improved and the temperature of the raised working fluid can be lowered.

  (9) In order to achieve the above object, the present invention provides a plurality of variable displacement hydraulic pumps, a plurality of driven bodies driven by each of the plurality of hydraulic pumps, and a working fluid that is a drive medium. A construction machine that reduces a capacity of the plurality of hydraulic pumps to a preset minimum capacity when the plurality of driven bodies are in a non-operating state. A first detection means for detecting an operation pattern in which the temperature of the working fluid rises among operation patterns related to the driving body, and at least one of the plurality of hydraulic pumps based on the operation pattern detected by the first detection means. And a pump flow rate increasing means for increasing the minimum capacity of some of the hydraulic pumps and increasing the average flow rate of the working fluid passing through the heat exchanger.

  As a result, in a hydraulic system including a plurality of hydraulic pumps, a heat exchanger is predicted in advance (before the temperature of the working fluid) by predicting the temperature rise of the working fluid by the same action as described in (1) above. It is possible to increase the average amount of heat released (increase the cooling performance) and lower the equilibrium temperature of the working fluid, thereby preventing the temperature of the working fluid from rising and reducing the failure of the hydraulic equipment and improving the service life. It becomes. Moreover, since the cooling performance is improved by increasing the minimum flow rate of the hydraulic pump and increasing the average flow rate of the working fluid passing through the heat exchanger, noise and fuel consumption are not deteriorated.

  (10) In the above (9), the first detection means is a first driven body driven by a part of the plurality of hydraulic pumps as an operation pattern in which the temperature of the working fluid rises. The pump flow rate increasing means increases the minimum capacity of the hydraulic pumps other than the some hydraulic pumps based on the operation pattern related to the first driven body.

  As a result, when there are multiple hydraulic pumps, the cooling performance of the heat exchanger is improved by effectively using available hydraulic pumps (hydraulic pumps other than the ones mentioned above), and the temperature of the working fluid rises. Can be prevented in advance.

  According to the present invention, by increasing the cooling performance before the temperature of the working fluid rises, the temperature rise of the working fluid can be prevented in advance, and the failure of the hydraulic equipment can be reduced and the life can be improved. In addition, the cooling capacity is improved by increasing the minimum capacity of the hydraulic pump and increasing the average flow rate of the working fluid that passes through the heat exchanger, so noise deterioration does not occur and fuel consumption deterioration is minimized. Can do.

It is a figure which shows the working fluid cooling control system of the construction machine by one embodiment of this invention with a hydraulic drive device. It is a figure which shows the relationship between the operation amount of an operation lever or a pedal in operation means, such as an operation lever apparatus, a travel pedal apparatus, and the operation lever apparatus for crushers, and output pilot pressure (operation pilot pressure). It is a figure which shows the positive control function of a tilt control mechanism. It is a figure which shows the absorption torque limitation control function of a tilt control mechanism. 1 is a side view of a wheel excavator on which a hydraulic drive device according to the present embodiment is mounted. It is a figure which shows a part of front work machine which attached the crusher instead of the bucket as a work machine attachment. It is a functional block diagram which shows the detail of the calculation process of the 1st minimum pump inclination calculating part of a controller. It is a functional block diagram which shows the detail of the calculation process of the 2nd minimum pump inclination calculating part of a controller. It is a functional block diagram which shows the detail of the arithmetic processing of the control signal generation part of a 1st minimum pump inclination calculating part. It is a functional block diagram which shows the detail of the arithmetic processing of the control signal generation part of a 2nd minimum pump inclination calculating part.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a working fluid cooling control system for a construction machine according to the present embodiment together with a hydraulic drive device (hydraulic system).

  In FIG. 1, the hydraulic drive device includes two variable displacement hydraulic pumps 11 and 12 and two control valve groups 20 and 21. The hydraulic pumps 11 and 12 are provided with tilt control mechanisms 13 and 14 for controlling respective tilt angles.

  The control valve group 20 includes a plurality of control valves including center bypass type control valves 22, 23 and 24, and is connected to the hydraulic pump 11. The control valve group 21 includes a plurality of control valves including center bypass type control valves 26, 27 and 28, and is connected to the hydraulic pump 12. Each control valve is connected to various hydraulic actuators constituting the driven body, controls the flow of pressure oil discharged from the hydraulic pumps 11 and 12, and drives and controls the corresponding hydraulic actuator.

  The control valve 22 of the control valve group 20 is for a boom, for example, and is connected to a boom cylinder 214 (see FIG. 5) as a corresponding hydraulic actuator.

  The control valve 26 of the control valve group 21 is for traveling, and is connected to a hydraulic motor 32 as a corresponding hydraulic actuator. On the pipe line connecting the control valve 26 and the hydraulic motor 32, a counter balance valve 34 and crossover relief valves 33, 33 are provided.

  The control valve 23 of the control valve group 20 and the control valve 27 of the control valve group 21 are spare control valves, and are used when a work machine attachment other than a bucket (hereinafter referred to as an optional attachment) is mounted. There are various optional attachments such as a crusher (breaker) and a breaker. When these optional attachments are mounted, the hydraulic actuators of the respective optional attachments are connected to the control valves 23 and 27 using the connectors 29 and 30. FIG. 1 shows a case where a hydraulic cylinder 218 of a crusher is connected to the control valves 23 and 27. The crusher is an attachment that requires a large flow rate and high horsepower, and an option selection switch 103 is provided for using an attachment that requires a large flow rate and high horsepower such as a crusher. Further, a merging switching valve 36 is provided on the actuator line side of the control valves 23 and 27. The option selection switch 103 is an operation mode switching means. When the option selection switch 103 is pressed, the crushing mode is selected, a switching signal is sent from a mode switching control (not shown) to the merging switching valve 36, and the merging switching valve 36 is merged. The position is switched to the position (open position), and the discharge pressures of the hydraulic pumps 11 and 12 are supplied to the hydraulic cylinder 218 of the crusher. At the same time, a signal is sent from the mode switching control to a fuel injection amount control device (not shown) of the engine 10 to increase the rotational speed of the engine 10.

  An operating lever device 50 is provided as an operating means for the boom control valve 22, and a traveling pedal device 51 is provided as an operating means for the traveling control valve 26, and a spare control valve 23 used for a crusher. As an operation means for the operation unit 27, an operation lever device 52 for crusher is provided.

  The operation lever device 50 includes an operation lever 50a and a pilot valve portion 50b, and generates an operation pilot pressure in either of the pilot lines 50c and 50d according to the operation direction and the operation amount of the operation lever 50a. Is switched by the operating pilot pressure.

  The traveling pedal device 51 has a traveling pedal 51a and a pilot valve portion 51b, and generates an operating pilot pressure in either of the pilot lines 51c and 51d according to the depression amount of the traveling pedal 51a, and the control valve 26 has its operating pilot pressure. It is switched by.

  The crusher operation lever device 52 includes an operation lever 52a and a pilot valve portion 52b, and generates an operation pilot pressure in either of the pilot lines 52c and 52d according to the operation direction and the operation amount of the operation lever 52a. The control valves 23 and 27 are switched by the pilot pressure.

  An operation lever device similar to the operation lever device 50 is provided for the other control valves 24.

  The pilot lines 50c and 50d to which the pilot pressure of the operating lever device 50 is output are provided with a shuttle valve 60 as means for detecting the amount of boom operation, and the pilot lines 51c and 51d to which the pilot pressure of the traveling pedal device 51 is output are provided. A shuttle valve 61 is provided as a travel operation amount detection means, and a shuttle valve 62 is provided as a crusher operation amount detection means in the pilot lines 52c and 52d to which the pilot pressure of the operation lever device 52 is output. A similar shuttle valve is provided in the other operation lever devices.

  The pilot pressure detected by the shuttle valves 60, 62,... Related to the control valve group 20 is guided to the high pressure selection valve block 63 through the signal oil passage 71. The high pressure selection valve block 63 selects the highest pressure, and the highest pressure is output to the signal oil passage 73 as the pump command pressure P1P of the positive control.

  Similarly, the pilot pressures detected by the shuttle valves 26, 27... Related to the control valve group 21 are guided to the high pressure selection valve block 64 via the signal oil passage 72, and the high pressure selection valve block 64 controls their pressures. The highest pressure is selected, and the highest pressure is output to the signal oil passage 74 as the pump command pressure P2P of the positive control.

  The tilt control mechanism 13 inputs the positive control command pressure P1P from the signal oil passage 75, and the tilt of the hydraulic pump 11 is increased so that the tilt angle (push-up volume) of the hydraulic pump 11 increases as the command pressure increases. Control the corners. Further, the tilt control mechanism 13 inputs the discharge pressure of the hydraulic pump 11 related to itself from the signal oil passage 76, inputs the discharge pressure of the other hydraulic pump 12 from the signal oil passage 77, and averages the hydraulic pumps 11 and 12. When the discharge pressure exceeds the set value, the tilt angle of the hydraulic pump 11 is decreased as the average discharge pressure increases, and the tilt angle of the hydraulic pump 11 is controlled so as to keep the absorption torque of the hydraulic pumps 11 and 12 constant. To do.

  The tilt control mechanism 14 is the same, and a positive control command pressure P2P is input from the signal oil passage 78, and the tilt angle (displacement volume) of the hydraulic pump 12 increases as the command pressure increases. 12 tilt angles are controlled. Further, the tilt control mechanism 14 inputs the discharge pressure of the hydraulic pump 12 related to itself from the signal oil passage 79, inputs the discharge pressure of the other hydraulic pump 11 from the signal oil passage 80, and averages the hydraulic pumps 11 and 12. When the discharge pressure exceeds the set value, the tilt angle of the hydraulic pump 12 is decreased as the average discharge pressure increases, and the tilt angle of the hydraulic pump 12 is controlled so as to keep the absorption torque of the hydraulic pumps 11 and 12 constant. To do.

  The hydraulic oil (hydraulic fluid) discharged from the hydraulic pumps 11 and 12 and passing through the control valve groups 20 and 21 is supplied from the discharge line 43 directly or as return oil from hydraulic actuators such as the hydraulic motor 32 and the boom cylinder 218. Returned to the tank 42. The discharge line 43 is provided with an oil cooler 40 for cooling the pressure oil returned to the hydraulic oil tank 42. The oil cooler 40 is cooled by a cooling fan 41. The cooling fan 41 is rotationally driven by the engine 10 together with the hydraulic pumps 11 and 12.

  The hydraulic fluid drive apparatus as described above is provided with the working fluid cooling control system of the present embodiment. This system includes a travel motor rotational speed pickup 101, a pressure sensor 102, a signal capture line 103 a of an option selection switch 103, and a temperature sensor 104. The travel motor speed pickup 101, the pressure sensor 102, and the signal take-in line 103a of the option selection switch 103 are provided as detection means for detecting an operation pattern in which the temperature of the hydraulic fluid in the circuit increases. The traveling motor rotational speed pickup 101 detects the vehicle speed by detecting the rotational speed of the hydraulic motor 32, and the pressure sensor 102 detects the pilot pressure in the signal oil path 72, thereby operating the operating amount (depression amount) of the traveling pedal 51 a. ) And the signal take-in line 103a of the option selection switch 103 is an operation pattern that uses an attachment (for example, a crusher) that requires a large flow rate and high horsepower by taking a mode switching signal of the option selection switch 103. Detect that. The temperature sensor 104 is provided in the hydraulic oil tank 42 and detects the temperature (oil temperature) of the hydraulic fluid in the circuit.

  In addition, the working fluid cooling control system of the present embodiment includes a controller 100, proportional solenoid valves 105 and 106, and shuttle valves 109 and 110. The controller 100 inputs the detection signals of the traveling motor rotation speed pickup 101, the pressure sensor 102, the signal take-in line 103a of the option selection switch 103, and the temperature sensor 104, performs predetermined processing, and solenoids of the proportional solenoid valves 105 and 106 Control currents I1c and I2c (control signals) are output to the sections 105a and 106a. Proportional solenoid valves 105 and 106 output control pressures P1C and P2C corresponding to the control signals to signal oil passages 107 and 108, respectively. The shuttle valve 109 is provided between the signal oil passage 73 on the output side of the high pressure selection valve block 63 and the signal oil passage 107, and the positive control pump command pressure P1P selected by the high pressure selection valve block 63 and the proportional electromagnetic A high pressure side with respect to the control pressure P1C output from the valve 105 is selected and output to the signal oil passage 75 of the tilt control mechanism 13.

Similarly, the shuttle valve 110 is provided between the signal oil passage 74 on the output side of the high pressure selection valve block 64 and the signal oil passage 108, and the positive control pump command pressure P2P selected by the high pressure selection valve block 64 The high pressure side of the control pressure P2C output from the proportional solenoid valve 106 is selected and output to the signal oil passage 78 of the tilt control mechanism 14.
FIG. 2 is a diagram showing the relationship between the operation amount of the operation lever or pedal and the output pilot pressure (operation pilot pressure) in the operation means such as the operation lever device 50, the traveling pedal device 51, and the crusher operation lever device 52.
In FIG. 2, the operation pilot pressure is zero (tank pressure) while the operation amount is in the dead zone A1, and when the operation amount exceeds A1, the minimum pilot pressure PminOP is increased until the operation amount reaches A2. When the output pilot pressure increases up to the pilot pressure PmaxOP and the operation amount exceeds A2, the operation pilot pressure becomes constant at the maximum pressure PmaxOP.

  FIG. 3 is a diagram showing the positive control function of the tilt control mechanisms 13, 14, the horizontal axis indicates the pressure input to the tilt control mechanisms 13, 14, and the vertical axis is controlled by the tilt control mechanisms 13, 14. The tilt angles of the hydraulic pumps 11 and 12 are shown.

  In FIG. 3, the tilt angles of the hydraulic pumps 11 and 12 are constant at qmin1 (q1min1, q2min1) until the input pressure is up to Pmin1 (P1min1, P2min1), and when the input pressure exceeds Pmin1, the input pressure is increased. The tilt angle increases from the minimum tilt angle qmin1 to the maximum tilt angle qmax (q1max, q2max) until reaching Pmax, and when the input pressure exceeds Pmax, the tilt angle becomes constant at the maximum value qmax. .

  The minimum tilt angle qmin1 is a minimum tilt angle set for the purpose of ensuring self-lubricity of the hydraulic pumps 11 and 12, and the maximum tilt angle qmax is a maximum tilt angle determined by the specifications of the hydraulic pumps 11 and 12. .

  FIG. 4 is a diagram illustrating the absorption torque limiting control function of the tilt control mechanisms 13 and 14, where the horizontal axis indicates the average value of the discharge pressure of the hydraulic pumps 11 and 12, and the vertical axis indicates the maximum tilt of the hydraulic pumps 11 and 12. The turning angle (maximum displacement) is shown. The maximum tilt angle means a limit value of the tilt angle.

  In FIG. 4, the maximum tilt angle of the hydraulic pumps 11 and 12 is the maximum at qmax (q1max, q2max) while the average value of the discharge pressures of the hydraulic pumps 11 and 12 is Pa, and the discharge of the hydraulic pumps 11 and 12 is maximum. When the average value of the pressure exceeds Pa, the tilt angle of the hydraulic pumps 11 and 12 decreases as the discharge pressure of the hydraulic pumps 11 and 12 increases. Pmax is a relief pressure of a main relief valve (not shown) connected to the discharge oil passages of the hydraulic pumps 11 and 12.

  When the target tilt angle by the positive control function of FIG. 3 is smaller than the maximum tilt angle corresponding to the pump pressure average value at that time, the tilt control mechanisms 13 and 14 are hydraulic. The tilt angle of the hydraulic pumps 11 and 12 is controlled so that the tilt angle of the pumps 11 and 12 becomes the tilt angle by the positive control function, and the tilt angle by the positive control function is the maximum tilt angle by the absorption torque limit control function. Is exceeded, the tilt angles of the hydraulic pumps 11 and 12 are controlled so that the tilt angles of the hydraulic pumps 11 and 12 are limited to the maximum tilt angle. As a result, the total absorption torque of the hydraulic pumps 11 and 12 is controlled so as not to exceed the torque curve Tn of FIG. A torque curve Tn in FIG. 4 is a curve showing the vicinity of the maximum output torque in the regulation region of the engine 10. Thereby, engine stall due to overload of the engine 10 can be prevented.

  If the vertical axis in FIG. 4 is replaced with the pump flow rate, horsepower control is performed, and Tn becomes a horsepower curve. Control in which the horizontal axis in FIG. 4 is the average value of the discharge pressures of the hydraulic pumps 11 and 12 is called full horsepower control.

FIG. 5 is a side view of a wheel excavator on which the hydraulic drive device according to the present embodiment is mounted.
In FIG. 5, the wheel excavator 201 includes a lower traveling body 202, an upper swing body 203 rotatably mounted on the lower traveling body 202, and a front work machine 204. The lower traveling body 202 includes a front wheel 205 and a rear wheel 206, and the rear wheel 206 is driven by the hydraulic motor 32 shown in FIG.

  The upper swing body 203 includes a so-called cabin type cab 209 and an exterior cover 210 that covers most of the upper swing body 203 other than the cab 209. The engine 10, the hydraulic pumps 21, 22 and the like shown in FIG.

  The front work machine 204 includes a boom 211, an arm 212 rotatably connected to the boom 211, and a bucket 213 rotatably connected to the arm 212. The boom 211, arm 212, and bucket 213 are respectively It is driven by a boom cylinder 214, an arm cylinder 215, and a bucket cylinder 216.

FIG. 6 is a diagram showing a part of the front work machine 204 in which a crusher 217 is mounted instead of the bucket 213 as a work machine attachment.
The crusher 217 is one of work machine attachments, and is attached to the front end of the work machine instead of the bucket 213 and incorporates the actuator 218 shown in FIG. The actuator 218 shown in FIG. 1 requires a large flow rate (for example, two pumps) and high horsepower compared to the bucket cylinder 216.

  7 and 8 are functional block diagrams showing details of the arithmetic processing of the controller 100. FIG.

  As shown in FIG. 7, the controller 100 inputs detection signals from the traveling motor rotation speed pickup 101, the pressure sensor 102, the signal selection line 103 a of the option selection switch 103, and the temperature sensor 104, and the minimum inclination of the hydraulic pump 11. A first minimum pump tilt calculation unit 111 that outputs a control signal for increasing the rotation angle to the proportional solenoid valve 105, and a signal take-in line of the travel motor rotation speed pickup 101 and the option selection switch 103 as shown in FIG. 103a, a second minimum pump tilt calculation unit 112 that inputs each detection signal from the temperature sensor 104 and outputs a control signal for increasing the minimum tilt angle of the hydraulic pump 12 to the proportional solenoid valve 106. ing.

  In FIG. 7, the first minimum pump tilt calculation unit 111 includes a minimum tilt calculation unit 111 a based on vehicle speed, a minimum tilt calculation unit 111 b based on a travel operation amount, a minimum tilt calculation unit 111 c based on a mode switching signal, an oil There is a minimum tilt calculation unit 111d by temperature, a maximum value selection unit 111e, and a control signal generation unit 111f.

  The minimum tilt calculation unit 111a based on the vehicle speed inputs the rotational speed of the hydraulic motor 32 from the traveling motor rotational speed pickup 101 as vehicle speed information, refers to this information in a table stored in advance in the memory, and corresponds to the vehicle speed at that time The minimum tilt angle q1mina of the hydraulic pump 11 is calculated. In the table stored in the memory, as shown in FIG. 7, the minimum tilt angle q1mina is set to the minimum tilt angle q1min1 shown in FIG. As the vehicle speed increases from V1 to V2, the minimum tilt angle q1mina increases from q1min1 to q1min2, and when the vehicle speed becomes higher than V2, the minimum tilt angle q1mina is constant at q1min2. The relationship between the vehicle speed and the minimum tilt angle q1mina is set.

  The minimum tilt calculation unit 111b based on the travel operation amount inputs the pilot pressure of the signal oil path 72 as the pedal operation amount (depression amount) information of the travel pedal 51a from the pressure sensor 102, and this information is stored in a memory in advance in a table. The minimum tilt angle q1minb of the hydraulic pump 11 corresponding to the pedal operation amount at that time is calculated. In the table stored in the memory, as shown in FIG. 7, the minimum tilt angle q1minb is set to the tilt control mechanism 13 until A1 where the pedal operation amount is small, as shown in FIG. As the pedal operation amount increases from A1 to A2, the minimum tilt q1minb increases from q1min1 to q1min2, and when the pedal operation amount exceeds A2, the minimum tilt angle q1minb becomes constant at q1min2. As described above, the relationship between the pedal operation amount and the minimum tilt angle q1minb is set.

  The minimum tilt calculation unit 111c based on the mode switching signal inputs a mode switching signal (option switch signal) from the signal take-in line 103a of the option selection switch 103, refers to this signal in a table previously stored in the memory, and A minimum tilt angle q1minc of the hydraulic pump 11 corresponding to the switching signal information is calculated. In the table stored in the memory, as shown in FIG. 7, when the signal of the option selection switch 103 is OFF, the minimum tilt angle q1minc is set to the tilt control mechanism 13 as shown in FIG. The relationship between the mode switching signal and the minimum tilt angle q1minc is set so that the minimum tilt angle q1minc becomes q1min2 when the signal of the option selection switch 103 is ON, which is the same value as q1min1.

  The minimum tilt calculation unit 111d based on the oil temperature inputs the oil temperature information of the hydraulic oil tank 42 from the temperature sensor 104, refers to this information in a table stored in advance in the memory, and the hydraulic pressure corresponding to the oil temperature at that time The minimum tilt angle q1mind of the pump 11 is calculated. In the table stored in the memory, as shown in FIG. 7, the minimum tilt angle q1mind is set in the tilt control mechanism 13 until the oil temperature reaches T1, which is the upper limit of the normal temperature range. It is the same constant value as the minimum tilt angle q1min1 shown, the minimum tilt angle q1mind increases from q1min1 to q1min2 as the oil temperature increases from T1 to T2, and the minimum tilt angle increases when the oil temperature becomes higher than T2. The relationship between the oil temperature and the minimum tilt angle q1mind is set so that the angle q1mind is constant at q1min2.

  The maximum value selection unit 111e includes a minimum tilt calculation unit 111a based on vehicle speed, a minimum tilt calculation unit 111b based on travel operation amount, a minimum tilt calculation unit 111c based on a mode switching signal, and a minimum tilt calculation unit 111d based on oil temperature. The calculated minimum tilt angles q1mina, q1minb, q1minc, q1mind of the hydraulic pump 11 are input, the maximum value among them is selected as q1minx, and is output to the control signal generator 111f.

  FIG. 9 is a functional block diagram showing details of the arithmetic processing of the control signal generator 111f. The control signal generator 111 f includes a control pressure calculator 151, a control current calculator 152, and an amplifier 153. The control pressure calculation unit 151 inputs the maximum value q1minx, refers to this information in a table stored in advance in the memory, and calculates the corresponding target control pressure P1CO. In the table described in the memory, the relationship between the maximum value q1minx and the target control pressure P1CO as shown in FIG. 9 is set. This relationship is an inverse function of the relationship between the operation pilot pressure and the tilt angles of the hydraulic pumps 11 and 12 to be controlled as shown in FIG.

  The control current calculation unit 152 inputs the target control pressure P1CO, refers to this information in a table stored in advance in the memory, and calculates the target control current I1CO corresponding to the target control pressure P1CO at that time. The relationship between the target control pressure P1CO and the target control current I1CO is set in the memory table so that the target control current I1CO increases as the target control pressure P1CO increases.

  The amplifying unit 153 amplifies the target control current I1CO to obtain the control current I1C, and outputs this to the solenoid 105a of the proportional solenoid valve 105.

  The proportional solenoid valve 105 is operated by the control current I1C input to the solenoid 105a, and outputs the corresponding control pressure P1C. The control pressure P1C is a pressure corresponding to the target control pressure P1CO calculated by the control pressure calculation unit 151 at that time.

  In FIG. 8, the second minimum pump tilt calculation unit 112 includes a minimum tilt calculation unit 112a based on vehicle speed, a minimum tilt calculation unit 112c based on a mode switching signal, a minimum tilt calculation unit 112d based on oil temperature, and a maximum value. A selection unit 112e and a control signal generation unit 112f are included.

  The minimum tilt calculation unit 112a based on the vehicle speed inputs the rotation speed of the hydraulic motor 32 from the traveling motor rotation speed pickup 101 as vehicle speed information, refers to this information in a table stored in advance in the memory, and stores the vehicle speed information at that time. The minimum tilt angle q2min of the corresponding hydraulic pump 12 is calculated. In the table stored in the memory, as shown in FIG. 8, the minimum inclination angle q2mina is set to the minimum inclination angle q2min1 shown in FIG. As the vehicle speed increases from V1 to V2, the minimum tilt angle q2min increases from q2min1 to q2min2, and when the vehicle speed becomes higher than V2, the minimum tilt angle q2mina is constant at q2min2. The relationship between the vehicle speed and the minimum tilt angle q2min is set.

  The minimum tilt calculation unit 112c based on the mode switching signal inputs a mode switching signal (option switch signal) from the signal fetch line 103a of the option selection switch 103, refers to this signal in a table stored in advance in the memory, and A minimum tilt angle q2minc of the hydraulic pump 12 corresponding to the switching signal information is calculated. In the table stored in the memory, as shown in FIG. 8, when the option selection switch 103 is OFF, the minimum tilt angle q2minc is the minimum tilt angle q2min1 shown in FIG. When the option selection switch 103 is ON, the relationship between the mode switching signal and the minimum tilt angle q2minc is set so that the minimum tilt angle q2minc is q2min2.

  The minimum tilt calculation unit 112d based on the oil temperature inputs the oil temperature information of the hydraulic oil tank 42 from the temperature sensor 104, refers to this information in a table stored in advance in the memory, and corresponds to the oil temperature information at that time The minimum tilt angle q2mind of the hydraulic pump 11 is calculated. In the table stored in the memory, as shown in FIG. 8, the minimum tilt angle q2mind is set to the tilt control mechanism 14 until the oil temperature reaches the minimum T1, and the minimum tilt angle shown in FIG. It is the same constant value as q2min1, and as the oil temperature increases from T1 to T2, the minimum tilt angle q2mind increases from q2min1 to q2min2, and when the oil temperature becomes higher than T2, the minimum tilt angle q2mind is q2min2. The relationship between the oil temperature and the minimum tilt angle q1mind is set so as to be constant.

  The maximum value selection unit 112e is the minimum tilt angle of the hydraulic pump 12 calculated by the minimum tilt calculation unit 112a based on the vehicle speed, the minimum tilt calculation unit 112c based on the mode switching signal, and the minimum tilt calculation unit 112d based on the oil temperature. q2mina, q2minc, and q2mind are input, the maximum value among them is selected as q2miny, and is output to the control signal generator 112f.

  FIG. 10 is a functional block diagram showing details of the arithmetic processing of the control signal generator 112f. The control signal generation unit 112f includes a control pressure calculation unit 161, a control current calculation unit 162, and an amplification unit 163. The control pressure calculation unit 161 inputs the maximum value q2miny, refers to this information in a table stored in advance in the memory, and calculates the corresponding target control pressure P2CO. In the table described in the memory, the relationship between the maximum value q2miny and the target control pressure P2CO as shown in FIG. 10 is set. This relationship is an inverse function of the relationship between the operation pilot pressure and the tilt angles of the hydraulic pumps 11 and 12 to be controlled as shown in FIG.

  The control current calculation unit 162 inputs the target control pressure P2CO, refers to this information in a table stored in advance in the memory, and calculates a target control current I2CO corresponding to the target control pressure P2CO at that time. In the table described in the memory, the relationship between the target control voltage P2CO and the target control current I2CO is set so that the target control current I2CO increases as the target control pressure P2CO increases.

  The amplifying unit 163 amplifies the target control current I2CO to obtain the control current I2C, and outputs this to the solenoid 106a of the proportional solenoid valve 106.

  The proportional solenoid valve 106 is operated by the control current I2C input to the solenoid 106a, and outputs a corresponding control pressure P2C. The control pressure P2C is a pressure corresponding to the target control pressure P2CO calculated by the control pressure calculation unit 161 at that time.

  In the above, the traveling motor rotation speed pickup 101, the pressure sensor 102, and the signal take-in line 103a of the option selection switch 103 are hydraulic fluids among the operation patterns related to the plurality of driven bodies 32, 214, 218,. The controller 100, the proportional solenoid valves 105 and 106, the shuttle valves 109 and 110, and the tilt control mechanisms 13 and 14 include the first detection unit. The pump flow rate increasing means is configured to increase the minimum capacity of the hydraulic pumps 11 and 12 based on the operation pattern detected by the means and increase the average flow rate of the hydraulic fluid passing through the oil cooler (heat exchanger) 40.

  The controller 100, the proportional solenoid valves 105 and 106, the shuttle valves 109 and 110, and the tilt control mechanisms 13 and 14 include a plurality of hydraulic pumps 11 and 12 based on the operation pattern detected by the first detection means. Among them, a pump flow rate increasing means for increasing a minimum capacity of at least a part of the hydraulic pump (hydraulic pump 11 or 12) and increasing an average flow rate of the working fluid passing through the oil cooler (heat exchanger) 40 is configured.

  The traveling motor rotation speed pickup 101 serving as the first detection means is driven by a hydraulic pump 12 that is a part of the plurality of hydraulic pumps 11 and 12 as an operation pattern in which the temperature of the hydraulic fluid rises. In this case, the pump flow rate increasing means is based on the operation pattern related to the first driven body (travel motor 32). The minimum capacity of the hydraulic pump 11 that is not only the hydraulic pump 12 that is a part of the hydraulic pumps but also the hydraulic pumps that are other than that is configured to be increased. In this case, the pump flow rate increasing means increases the minimum capacity of only the hydraulic pump 11 that is a hydraulic pump other than the part of the hydraulic pumps based on the operation pattern related to the first driven body (travel motor 32). You may comprise as follows.

Next, the operation of the present embodiment will be described.
First, a description will be given of a normal operation performed by attaching the bucket 213 to the front work machine 204.

  During normal operation, when all the operation means such as the operation lever device 50 and the travel pedal device 51 are not operated, the pilot pressure output from the operation means is zero (tank pressure), and the signal oil path The pressures 73 and 74 are also zero (tank pressure).

  On the other hand, during normal work, the option selection switch 103 is OFF (normal work mode), and the values of the detection signals from the traveling motor rotation speed pickup 101 and the pressure sensor 102 are also zero because of no operation. Further, when the oil temperature of the hydraulic oil tank 42 is in a normal temperature range, the detection signal of the temperature sensor 104 also has a value corresponding thereto. Therefore, in this case, in the first minimum pump tilt calculation unit 111 and the second minimum pump tilt calculation unit 112 of the controller 100, q1min1 and q2min1 are calculated as the minimum tilt angles, and the control currents I1C and I2C corresponding thereto are calculated. Is output to the proportional solenoid valves 105 and 106, and the control pressures P1C and P2C corresponding to q1min1 and q2min1 are output from the proportional solenoid valves 105 and 106. The control pressures P1C and P2C are pressures corresponding to the target control pressures P1min1 and P2min1 calculated by the control pressure calculation units 151 and 161 in FIGS. As a result, the control pressures P1C and P2C are selected in the shuttle valves 109 and 110, the control pressures P1C and P2C are input to the tilt control mechanisms 13 and 14, and the tilt angles of the hydraulic pumps 11 and 12 are q1min1, It is controlled to be q2min1. This is the same control result as when the pressure (zero) in the signal oil passages 73 and 74 is input to the tilt control mechanisms 13 and 14 as the pump command pressure (prior art).

  From this state, for example, when the operator operates the operation lever 50a of the operation lever device 50 with the intention of moving the boom 211, an operation pilot pressure is generated in one of the pilot lines 50c and 50d, and the control valve 22 It is switched by pressure. At the same time, the pressure is detected by the shuttle valve 60, further selected by the high pressure selection valve block 63, and output to the signal oil passage 73 as the pump command pressure P1P.

  On the other hand, the signal from the signal selection line 103a of the option selection switch 103 and the detection signal values from the traveling motor rotation speed pickup 101, the pressure sensor 102, and the temperature sensor 104 input to the controller 100 at this time are in the above-described non-operation state. The pressure corresponding to the target control pressures P1min1 and P2min1 (<P1P) is output to the signal oil passages 107 and 108. As a result, the pump command pressure P1P is selected in the shuttle valve 109. In the tilt control mechanism 13, the tilt of the hydraulic pump 11 is controlled by the positive flow rate control (FIG. 3) and the absorption torque limit control (FIG. 4) described above based on the pump command pressure P1P and the discharge pressure average value of the hydraulic pumps 11 and 12. The roll is controlled.

  When other operating means related to the control valve group 20 are operated, and when operating means other than the traveling pedal device 51 related to the control valve group 21 are operated, the same operation as in the normal operation is performed.

  Next, a description will be given of traveling performed by operating the traveling pedal 51a of the traveling pedal device 51.

  When the travel amount is small and the vehicle speed is low (vehicle speed <V1), the first minimum pump tilt calculation unit 111 and the second minimum pump tilt calculation unit 112 of the controller 100 set the minimum tilt angle as the operation amount of the travel pedal 51a. Since q1min1 and q2min1 are calculated, it is the same as in the normal operation. That is, in the tilt control mechanism 14, the positive flow rate control (FIG. 3) and the absorption torque limit control (FIG. 4) described above are performed based on the pump command pressure P2P and the discharge pressure average value of the hydraulic pumps 11 and 12, and the hydraulic pump 12 is controlled. Tilt is controlled.

  When the traveling pedal 51a is fully operated with the intention of traveling at a high speed on a flat road, a high pilot pressure is output from the operation lever device 51 to one of the pilot lines 51c and 51d, and the control valve 26 is switched by the pilot pressure. It is done. At the same time, the pressure is detected by the shuttle valve 61, further selected by the high pressure selection valve block 64, and output to the signal oil path 74 as the pump command pressure P2P. The pump command pressure P2P is compared with the control pressure P2C by the shuttle valve 110. At this time, since the travel pedal 51a is fully operated and P2P> P2min2, P2P> P2C is established. P2P is selected, and the pump command pressure P2P is input to the tilt control mechanism 14.

  In the tilt control mechanism 14, the tilt of the hydraulic pump 12 is controlled by the positive flow rate control (FIG. 3) and the absorption torque limit control (FIG. 4) described above based on the pump command pressure P2P and the discharge pressure average value of the hydraulic pumps 11 and 12. The roll is controlled.

  For example, since the traveling load is high during acceleration, the discharge pressure of the hydraulic pump 12 becomes a high pressure equal to or higher than Pa in FIG. 4, and even if the target inclination by the positive control of the pump command pressure P2P is, for example, qmax in FIG. The tilt angle of the hydraulic pump 12 is limited to a tilt angle smaller than qmax. The hydraulic pump 12 is supplied with hydraulic oil at a flow rate corresponding to the tilt angle from the hydraulic pump 12, and the vehicle body is adjusted to the flow rate. Drive at the appropriate speed.

  During steady running after the end of acceleration, when the discharge pressure of the hydraulic pump 12 becomes a low pressure near Pa or less in FIG. 4, the maximum tilt angle by the absorption torque limit control is the same as the target tilt by the positive control of the pump command pressure P2p. Since it becomes qmax, the tilt angle of the hydraulic pump 12 is controlled to be qmax by positive control, and the hydraulic pump 12 discharges a large amount of pressure oil corresponding thereto. As a result, the traveling hydraulic motor 32 rotates at a high speed, and the vehicle body travels at a high speed.

  On the other hand, among the signals input to the controller 100 at this time, the value of the detection signal from the pressure sensor 102 is equal to or greater than A2 in FIG. 7 because the traveling pedal 51a is in the full operation state, and the first minimum pump tilt calculation unit. The target tilt calculation unit 111b based on the travel operation amount 111 calculates q1min2 as the minimum tilt angle q1minb, and the q1min2 is selected as q1minx by the maximum value selection unit 111e and is output to the control signal generation unit 111f. From the control signal generator 111f, a control current I1C corresponding to q1minx (q1min2) is output to the proportional solenoid valve 105, and the proportional solenoid valve 105 outputs a control pressure P1C corresponding to the control oil path 107. The control pressure P1C is a pressure corresponding to P1min2 calculated by the control pressure calculation unit 151 in FIG. On the other hand, at this time, the pressure in the signal oil passage 73 is the tank pressure.

  As a result, the control pressure P1C is selected in the shuttle valve 109, the control pressure P1C is input to the tilt control mechanism 13, and the tilt angle of the hydraulic pump 11 is controlled to be q1min2 corresponding to P1min2. . That is, the minimum tilt angle of the hydraulic pump 11 increases from q1min1 to q1min2. As a result, the average flow rate of the pressure oil returned to the tank 42 via the discharge line 43 increases, the average heat release amount in the oil cooler 40 increases, and the equilibrium temperature of the hydraulic fluid can be lowered.

  When the travel pedal 51a is fully operated with the intention of traveling on an uphill road, the hydraulic pump 12 side uses a high pilot pressure from the travel pedal device 51 as in the case of high-speed travel on a flat road. The pump command pressure P2P based is selected by the shuttle valve 110 and input to the tilt control mechanism 14. The tilt control mechanism 14 tilts the hydraulic pump 12 by the positive flow rate control (FIG. 3) and the absorption torque limit control (FIG. 4) described above based on the pump command pressure P2P and the discharge pressure average value of the hydraulic pumps 11 and 12. The roll is controlled.

  Here, since the vehicle is traveling uphill, the traveling load is high, and the discharge pressure of the hydraulic pump 12 is a high pressure equal to or higher than Pa in FIG. For this reason, even if the target inclination by the positive control of the pump command pressure P2P is, for example, qmax in FIG. 3, the inclination angle of the hydraulic pump 12 is limited to an inclination angle smaller than qmax, and the hydraulic pressure for traveling from the hydraulic pump 12 is limited. The hydraulic oil is supplied at a flow rate corresponding to the tilt angle to the motor 32, and the vehicle body travels at a low speed.

  On the other hand, at this time, on the hydraulic pump 11 side, as in the case of high-speed traveling on a flat road, the minimum tilting is performed by the target tilt calculating unit 111b based on the travel operation amount in the first minimum pump tilt calculating unit 111 of the controller 100. Q1min2 is calculated as the angle q1minb, and the corresponding control pressure P1C is output from the proportional solenoid valve 105 to the signal oil passage 107. As a result, the control pressure P1C is selected in the shuttle valve 109, the control pressure P1C is input to the tilt control mechanism 13, and the tilt angle of the hydraulic pump 11 is controlled to be q1min2. That is, in this case as well, the minimum tilt angle of the hydraulic pump 11 increases from q1min1 to q1min2, thereby increasing the average flow rate of the pressure oil returned to the tank 42 via the discharge line 43 and the average discharge in the oil cooler 40. The amount of heat increases, and the equilibrium temperature of the hydraulic fluid can be lowered.

  When the travel pedal 51a is lightly operated for the purpose of traveling downhill, a low pilot pressure is output from the travel pedal device 51 to either of the pilot lines 51c and 51d, and the control valve 26 is controlled by the pilot pressure. Can be switched. At the same time, the pressure is detected by the shuttle valve 61, further selected by the high pressure selection valve block 64, and output to the signal oil path 74 as the pump command pressure P2P.

  On the other hand, of the signals input to the controller 100 at this time, the value of the detection signal from the traveling motor rotation speed pickup 101 is traveling on a downhill and may be V2 or more in FIG. Therefore, in this case, q2min2 is calculated as the minimum tilt angle q2min in the target tilt calculation unit 112a based on the vehicle speed of the second minimum pump tilt calculation unit 112, and the control pressure P2C corresponding to the q2min2 is applied to the signal oil path 108. Is output. The control pressure P2C is a pressure corresponding to P2min2 calculated by the control pressure calculation unit 161 in FIG.

  As a result, when the operation amount of the traveling pedal is small and P2P <P2C, the control pressure P2C is selected by the shuttle valve 110, the control pressure P2C is input to the tilt control mechanism 14, and the hydraulic pump 12 The tilt angle is controlled to be the tilt angle q2min2. That is, the tilt angle of the hydraulic pump 12 increases from the tilt angle of the positive control by the pump command pressure P2P to q2min2. In this case, the excess flow rate of the pressure oil discharged from the hydraulic pump 12 passes through the center bypass passage of the control valve 26 and returns to the tank 42 via the discharge line 43.

  Also on the hydraulic pump 11 side, when the vehicle speed is equal to or higher than V2, the minimum tilt angle q1mina is set by the target tilt calculation unit 111a based on the vehicle speed in the first minimum pump tilt calculation unit 111 of the controller 100 as in the hydraulic pump 12 side. q1min2 is calculated, and the control pressure P1C (corresponding to P1min2 calculated by the control pressure calculation unit 151 in FIG. 9) corresponding to the signal oil path 107 is output from the proportional solenoid valve 105. As a result, the control pressure P1C is selected in the shuttle valve 109, the control pressure P1C is input to the tilt control mechanism 13, and the tilt angle of the hydraulic pump 11 is controlled to be q1min2. That is, also on the hydraulic pump 11 side, the minimum tilt angle increases from q1min1 to q1min2.

  As described above, when traveling downhill, depending on the operating conditions, the tilt angle of not only the hydraulic pump 11 but also the hydraulic pump 12 increases from the tilt angle indicated by the pump command pressure P2P. In addition to the pressure oil from the hydraulic pump 12, the pressure oil from the hydraulic pump 12 side increases the average flow rate of the pressure oil that is returned to the tank 42 via the discharge line 43, and the average heat dissipation amount in the oil cooler 40 is increased. The equilibrium temperature of the oil fluid can be lowered.

  Although the case where the vehicle speed is V2 or more has been described on the hydraulic pump 11 side, even when the vehicle speed is between V1 and V2, the minimum tilt calculated by the target tilt calculation units 111a and 112a according to the vehicle speed is Since it increases from qmin1 between qmin1 and qmin2, the effect of improving the cooling performance by increasing the tilt angle (increasing discharge flow rate) of the hydraulic pumps 11 and 12 can be obtained accordingly.

  Next, the case where the crushing operation is performed by replacing the bucket 213 with the crusher 217 will be described. The crushing work performed using the crusher 217 is a work with a higher load frequency than the standard work.

  When the operator depresses the option selection switch 103 with the intention of crushing work such as dismantling work, the mode switching signal is switched from OFF to ON, and the ON signal is input to the controller 100 from the signal acquisition line 103a. In the minimum tilt calculation units 111c and 112c based on the mode switching signal in the first minimum pump tilt calculation unit 111 and the second minimum pump tilt calculation unit 112 of the controller 100, the minimum tilt angles q1minc and q2minc are determined by the ON signal. q1min2 and q2min2 are calculated, and control pressures P1C and P2C corresponding to the signal oil passages 107 and 108 are output.

  As a result, when the operation lever device 52 for crusher is not operated, such as when shifting from one crushing operation to another crushing operation, the hydraulic pumps 11 and 12 are at the minimum tilt. The turning angle increases from q1min1 to q1min2. As a result, the average flow rate of the pressure oil returned to the tank 42 via the discharge line 43 increases, the average heat release amount in the oil cooler 40 increases, and the equilibrium temperature of the hydraulic fluid can be lowered.

  Next, a case where the oil temperature in the hydraulic oil tank 42 has risen beyond the normal temperature range should be described during normal operation.

  There may be a case where the hydraulic oil temperature in the hydraulic system circuit increases due to operation in a place where the ambient temperature is very high, machine deterioration, etc., even during normal work.

  During normal operation, for example, when the oil temperature is equal to or higher than T2, target tilt calculation units 111d and 112d based on the oil temperature in the first minimum pump tilt calculation unit 111 and the second minimum pump tilt calculation unit 112 of the controller 100 are used. , Q1min2 and q2min2 are calculated as the minimum tilt angles q1mind and q2mind based on the detection signal of the temperature sensor 104 of the hydraulic oil tank 42, and the corresponding control pressures P1C and P2C are output.

  As a result, the minimum tilt angle of the hydraulic pumps 11 and 12 increases from q1min1 to q1min2 when there is no operation when all the operation means are not operated, and thus the pressure oil returned to the tank 42 via the discharge line 43 is increased. The average flow rate increases, the average heat release amount in the oil cooler 40 increases, and the equilibrium temperature of the hydraulic fluid can be lowered.

  According to the present embodiment, the following effects can be obtained.

  (1) Each signal from the signal acquisition line 103a of the traveling motor speed pickup 101, the pressure sensor 102, and the option selection switch 103 is input to the controller 100, and a traveling or a crusher having a high load frequency is used for standard work. In order to detect such an operation pattern at the time of crushing work (for example, dismantling work) and to increase the minimum tilt angle of the hydraulic pumps 11 and 12, the average passage flow rate of the hydraulic fluid of the oil cooler (heat exchanger) 40 is set. This can be increased in advance, thereby lowering the equilibrium temperature of the hydraulic fluid and preventing the temperature of the hydraulic fluid from rising.

  (2) The detection signal from the temperature sensor 104 is input to the controller 100, and it should be possible for the hydraulic system to operate in a place where the ambient temperature is very high, due to machine deterioration, etc. Even when the hydraulic oil temperature in the circuit rises, this is detected and the minimum tilt angle of the hydraulic pumps 11 and 12 is increased. Therefore, the average flow rate of the hydraulic fluid in the oil cooler (heat exchanger) 40 is increased. Can be increased in advance, thereby lowering the equilibrium temperature of the hydraulic fluid and quickly lowering the temperature of the raised hydraulic fluid.

  (3) As a result of (1) and (2) above, the frequency at which the temperature of the hydraulic fluid rises beyond the normal range is greatly reduced. As a result, the increase in wear of the sliding portion due to the reduction is reduced, and it becomes possible to reduce the failure of the hydraulic equipment and improve the service life.

  (4) Since the capacity of the hydraulic pumps 11 and 12 in the non-operation state when the operation means is neutral is controlled to the minimum capacity (minimum tilt angle) of either qmin1 or qmin2, the capacity is optimized. It is possible to reduce deterioration of fuel consumption and increase in heat generation due to increased pressure loss in the no-operation state. Further, the start shock of the driven body can be minimized.

  (5) Since the controller 100 determines whether or not it is necessary to increase the cooling capacity of the oil cooler (heat exchanger) 40, the operator's determination and manual operation are unnecessary, and usability (operability) is good.

  (6) During traveling, the hydraulic pump 11 (vacant hydraulic pump) that is not directly involved in traveling is used, the minimum tilt angle is increased, and the average passage of hydraulic fluid in the oil cooler (heat exchanger) 40 Since the flow rate is increased in advance, the cooling capacity can be increased more effectively and the temperature of the hydraulic fluid can be prevented from rising.

  In the above embodiment, the hydraulic drive apparatus having two hydraulic pumps (hydraulic pumps 11 and 12) has been described. However, the number of hydraulic pumps may be one, and in this case also (1) The effect of (5) can be acquired.

  Further, in the above embodiment, the traveling system is configured to operate only with the pressure oil from the hydraulic pump 12 side, but the pressure oils of both the hydraulic pumps 11 and 12 are joined and supplied to the traveling system for driving. It may be a thing.

  Furthermore, in the above embodiment, the operation mode in which the crusher performs the crushing operation as the operation mode with a high load frequency has been described. However, in the system having the operation mode such as the heavy excavation mode (power mode) and the fine operation mode, The heavy excavation mode (power mode) may be used.

  Further, when each signal from the traveling motor rotation speed pickup 101, the pressure sensor 102, the signal take-in line 103a of the option selection switch 103, and the temperature sensor 104 is input to the controller 100, the hydraulic oil temperature is expected to rise (in advance). When the hydraulic oil temperature rises (after the fact), the minimum tilt angle of the hydraulic pumps 11 and 12 is increased to increase the cooling capacity. However, when the hydraulic oil temperature is expected to rise (in advance) Only), the minimum tilt angle of the hydraulic pumps 11 and 12 may be increased. In this case as well, effects other than the above (2) can be obtained. In some cases, the minimum tilt angle of the hydraulic pumps 11 and 12 may be increased only when the temperature of the hydraulic oil rises (after the fact). In this case, effects other than the above (1) can be obtained. .

  Further, in the above embodiment, the minimum capacity (minimum tilt angle) of both the hydraulic pumps 11 and 12 is increased based on the signal of the traveling motor rotation speed pickup 101. However, the hydraulic pumps other than the hydraulic pumps related to traveling are used. The minimum capacity (minimum tilt angle) of only the hydraulic pump 11 may be increased. In this case as well, effects other than the above (2) can be obtained.

  Moreover, in the said embodiment, the minimum inclination calculating part 111a by the vehicle speed of the controller 100, the minimum inclination calculating part 111b by driving | running | working operation amount, the minimum inclination calculating part 111c by a mode switching signal, the minimum inclination calculating part by oil temperature 111d, minimum tilt calculation unit 112a based on vehicle speed, minimum tilt calculation unit 112c based on mode switching signal, and minimum tilt calculation unit 112d based on oil temperature, the minimum when an operating pattern in which the temperature of the hydraulic fluid rises is detected Although the tilt angles q1min2 and q2min2 are set to the same value, they may be arbitrarily changed according to the characteristics of each operation pattern. For example, when the vehicle speed increases on a downhill, the temperature rise due to the relief at the crossover relief valve 33 is often significant. Therefore, the minimum tilt calculation units 111a and 112a based on the vehicle speed, which are the calculation units in that case. If the minimum tilt angles q1min2 and q2min2 calculated in (2) are made larger, the cooling performance is improved accordingly, which is effective.

DESCRIPTION OF SYMBOLS 10 Engine 11, 12 Hydraulic pump 13, 14 Tilt control mechanism 20, 21 Control valve group 22-24, 26-28 Control valve 32 Hydraulic motor 40 Oil cooler 41 Cooling fan 42 Hydraulic oil tank 50 Operation lever apparatus 51 Traveling pedal apparatus 52 Operation lever device 60, 61, 62 Shuttle valve 63, 64 High pressure selection valve block 100 Controller 101 Traveling motor rotation speed pickup 102 Pressure sensor 103 Option selection switch 104 Temperature sensor 105, 106 Proportional solenoid valve 109, 110 Shuttle valve 202 Lower travel Body 203 Upper swing body 204 Front work machine 207 Blade 208 Blade cylinder 211 Boom 212 Arm 213 Bucket 214 Boom cylinder 215 Arm cylinder 216 Bucket cylinder 21 Crusher 218 actuator

Claims (10)

A variable displacement hydraulic pump, a plurality of driven bodies driven by the hydraulic pump, and a heat exchanger for cooling a working fluid that is a driving medium, wherein the plurality of driven bodies are brought into a non-operating state. Then, in the working fluid cooling control system of the construction machine that reduces the capacity of the hydraulic pump to a preset minimum capacity,
First detection means for detecting an operation pattern in which the temperature of the working fluid rises among operation patterns related to the plurality of driven bodies;
And a pump flow rate increase means for increasing the minimum capacity of the hydraulic pump based on the operation pattern detected by the first detection means and increasing the average flow rate of the working fluid passing through the heat exchanger. Machine working fluid cooling control system. The working fluid cooling control system for a construction machine according to claim 1,
The first detection means detects an operation state of a driven body having a high load frequency among the plurality of driven bodies as an operation pattern in which the temperature of the working fluid rises. Cooling control system. The working fluid cooling control system for a construction machine according to claim 2,
The working fluid cooling control system for a construction machine, wherein the first detection unit detects an operation signal of the operation unit of the driven body as an operation state of the driven body having a high load frequency. The working fluid cooling control system for a construction machine according to claim 2,
The working fluid cooling control system for a construction machine, wherein the first detecting means detects a driving speed of the driven body as an operation state of the driven body having a high load frequency. The working fluid cooling control system for a construction machine according to claim 1,
The first detecting means detects, as an operation pattern in which the temperature of the working fluid rises, an operation mode having a high load frequency among operation modes related to the plurality of driven bodies. Cooling control system. The working fluid cooling control system for a construction machine according to claim 5,
The construction machine further includes a selection means for selecting an operation mode using an attachment such as a crusher and other operation modes,
The working fluid cooling control system for a construction machine, wherein the first detection means detects an operation mode using the crusher as an operation mode having a high load frequency. The working fluid cooling control system for a construction machine according to claim 1,
A second detecting means for detecting the temperature of the working fluid;
The construction machine characterized in that the pump flow rate increasing means increases the minimum capacity of the hydraulic pump based on the operation pattern detected by the first detecting means and the temperature of the working fluid detected by the second detecting means. The construction machine according to claim 7,
The pump flow rate increasing means calculates a first minimum capacity based on the operation pattern detected by the first detecting means, and calculates a second minimum capacity based on the temperature of the working fluid detected by the second detecting means. And a means for selecting the larger one of the first minimum capacity and the second minimum capacity, and means for changing the minimum capacity of the hydraulic pump based on the selected minimum capacity. . A plurality of variable displacement hydraulic pumps, a plurality of driven bodies driven by each of the plurality of hydraulic pumps, and a heat exchanger for cooling a working fluid as a driving medium are provided. In a construction machine that reduces the capacity of the plurality of hydraulic pumps to a preset minimum capacity when the driving body is in an inoperative state,
First detection means for detecting an operation pattern in which the temperature of the working fluid rises among operation patterns related to the plurality of driven bodies;
A pump flow rate that increases the minimum flow rate of at least some of the plurality of hydraulic pumps based on the operation pattern detected by the first detection means and increases the average flow rate of the working fluid passing through the heat exchanger. A construction machine comprising an increasing means. The construction machine according to claim 9,
The first detection means is means for detecting an operation pattern related to a first driven body driven by a part of the plurality of hydraulic pumps as an operation pattern in which the temperature of the working fluid rises. Yes,
The construction machine characterized in that the pump flow rate increasing means increases a minimum capacity of a hydraulic pump other than the some hydraulic pumps based on an operation pattern related to the first driven body.

Images