JP7176976B2 - working machine - Google Patents

Description

The present invention relates to work machines.

Hydraulic oil, which is a driving medium for working machines such as hydraulic excavators, greatly changes its viscosity due to changes in temperature. For example, when the hydraulic oil is at a low temperature, its viscosity becomes high and its fluidity is poor. In addition, an engine (for example, a diesel engine) mounted on a working machine is connected to a hydraulic pump, so when the hydraulic oil is highly viscous, the load acting thereon causes a deterioration in fuel efficiency during work. Therefore, it is important to quickly increase the temperature of the hydraulic oil to lower the viscosity immediately after starting the working machine. On the other hand, considering the case where the thermal energy of the exhaust gas of the engine is discharged into the atmosphere as it is, in the case of a diesel engine, the effective energy efficiency is considerably low, about 40% even at the upper limit.

Therefore, it is considered to recover the thermal energy of the engine exhaust gas with a heat recovery device and reuse it for early temperature rise of the transmission hydraulic oil. A first circulation circuit for causing water to flow into the engine through a heater core, and a second circulation circuit for causing cooling water flowing out of the engine to flow into the engine through a hydraulic oil heat exchanger. A circulation circuit and a third circulation circuit for allowing the cooling water flowing out of the engine to flow into the engine without passing through the heater core and the hydraulic oil heat exchanger, and the circulation circuit is selected according to the situation. A cooling water circulation system is disclosed.

Patent No. 4998390

In the conventional technology, the overall energy efficiency can be improved by reusing the unused thermal energy of the exhaust gas. However, although the above-described conventional technology is optimized for a small amount of hydraulic oil such as the usage conditions in automobiles, it is suitable for early temperature rise of hydraulic oil when using a large amount of hydraulic oil such as in working machines. There was room for improvement in energy efficiency when applied to work machines, rather than being a technology that was easy to use.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a working machine capable of improving energy efficiency and rapidly raising the temperature of hydraulic oil.

The present application includes a plurality of means for solving the above problems. One example is an engine, a hydraulic pump driven by the engine, and a hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump. a hydraulic oil tank that stores the hydraulic oil; a radiator that cools the cooling water that cools the engine; a heater core that heats the air sent to the cab by the heat of the cooling water; and an outside air temperature detector. An outside air temperature sensor, a hydraulic oil heat exchanger that exchanges heat between the cooling water and the hydraulic oil, an exhaust heat recovery device that heats the cooling water with the heat of exhaust gas from the engine, and an exhaust heat recovery device that flows out from the engine. a first circulation circuit for flowing the cooled cooling water into the engine through the heater core and the exhaust heat recovery device; a second circulation circuit that flows into the engine through and a third circulation circuit that causes the cooling water that has flowed out of the engine to flow into the engine through the radiator; and the cooling water in the engine. A water temperature sensor for detecting temperature, a first control valve for adjusting the flow rate of the cooling water flowing into the heater core in the first circulation circuit, and a hydraulic oil heat exchanger in the second circulation circuit. a second control valve that adjusts the flow rate of the cooling water, a control device that adjusts the flow rate of the cooling water by controlling the opening degrees of the first to third control valves, and the third circulation A working machine comprising a thermostat valve provided between the radiator and the engine in a circuit for controlling the flow rate of the cooling water flowing from the radiator to the engine according to the temperature of the flowing cooling water and a third control valve for adjusting the flow rate of the cooling water flowing into the engine from the radiator in the third circulation circuit through the thermostat valve, wherein the control device controls the detection result of the outside air temperature sensor. is equal to or less than a predetermined reference temperature, the temperature when controlling the third control valve from the closed state to the open state is higher than the temperature of the cooling water when the thermostat valve changes from the closed state to the open state The degree of opening of the third control valve is controlled according to the detection result of the water temperature sensor so as to be higher than the temperature.

ADVANTAGE OF THE INVENTION According to this invention, energy efficiency can be improved and hydraulic oil can be heated up early.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing a hydraulic excavator as an example of a work machine equipped with a cooling water circulation system according to one embodiment; 1 is a diagram schematically showing an example of a cooling water circulating device mounted on a working machine along with related configurations; FIG. FIG. 4 is a partial cross-sectional view showing the configuration of an exhaust heat recovery device; 1 is a diagram showing an exhaust heat recovery device installed in an exhaust gas flow path of an engine together with its peripheral configuration; FIG. 1 is a diagram showing an exhaust heat recovery device installed in an exhaust gas flow path of an engine together with its peripheral configuration; FIG. It is a figure which shows the relationship with other structures of ECU which is a control apparatus. It is a functional block diagram which shows the processing content of ECU. 4 is a flow chart showing the contents of control of the cooling water circulation device by an ECU; FIG. 10 is a diagram showing switching between open and closed states of first to third control valves; FIG. 4 is a diagram showing switching of cooling water flow paths in the cooling water circulation device; FIG. 4 is a diagram showing switching of cooling water flow paths in the cooling water circulation device; FIG. 10 is a diagram showing changes in the degree of opening of the third control valve together with changes in the degree of opening of the thermostat valve; It is a figure which compares and shows the temperature change of a cooling water and hydraulic oil, and the change of the opening degree of a 3rd control valve. FIG. 10 is a diagram showing switching of the open/closed states of first to third control valves according to a modification;

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. 1 to 14. FIG. In this embodiment, a hydraulic excavator will be described as an example of a working machine. The present invention can also be applied to working machines.

FIG. 1 is a side view showing a hydraulic excavator, which is an example of a working machine equipped with a cooling water circulation system according to this embodiment. FIG. 2 is a diagram schematically showing an example of a cooling water circulating device mounted on a working machine, together with related configurations.

In FIG. 1, the hydraulic excavator is composed of a lower traveling body 1 and an upper revolving body 2 that constitute the vehicle body of the hydraulic excavator.

The lower traveling body 1 is composed of left and right crawler frames 4 (only one is shown) and crawlers 5 (only one is shown). run.

The upper revolving structure 2 is rotatably provided on the lower traveling structure 1, and is composed of a revolving frame 8, a cab 9 as an operator's cab, a machine room 10, and the like. The cab 9 has a substantially sealed structure that is isolated from the outside air in order to protect the driver from external noise, dust, etc., and is equipped with an air conditioning device (air conditioner) to ensure the comfort of the cabin, as well as an operator. A key switch for operating start/stop of the hydraulic excavator (that is, start/stop of the engine 100 to be described later) based on the operation of , hydraulic actuators of the front device 3 (boom cylinder 12, arm cylinder 14, bucket cylinder 16), etc. An operation device (not shown) for operating the is provided.

The front device 3 includes a boom 11 whose base end is rotatably connected to the upper rotating body 2, an arm 13 which is rotatably connected to an end different from the base end of the boom 11, and the arm 13. The boom 11, the arm 13, and the bucket 15 are rotated by a boom cylinder 12, an arm cylinder 14, and a bucket cylinder 16, which are hydraulic actuators, respectively. dynamically driven.

On the revolving frame 8 of the upper revolving body 2, there are an engine 100, a hydraulic pump 101 driven by the engine 100, a hydraulic oil tank 102 for storing hydraulic oil, and a boom cylinder 12 having a control valve (not shown). A hydraulic system for driving hydraulic actuators such as the arm cylinder 14 and the bucket cylinder 16 is mounted.

In addition, the body of the hydraulic excavator includes an outside air temperature sensor 70 for detecting the outside air temperature, a water temperature sensor 71 for detecting the temperature of cooling water for the engine 100, which will be described later, and a temperature sensor provided on the side of the cab 9 for detecting the temperature inside the cab 9. Sensors such as a room temperature sensor 72 that detects, an oil temperature sensor 73 that detects the temperature of the hydraulic oil stored in the hydraulic oil tank 102, and an operation amount sensor 74 that detects the operation amount of the operation device, and sensors from the sensors An ECU (Electric Control Unit) 300, which is a control device that controls the operation of the entire hydraulic excavator based on input signals, is mounted.

In FIG. 2, the cooling water circulation system includes a radiator 17 that cools the cooling water for cooling the engine 100, a heater core 40 that heats the air sent into the cab 9 with the heat of the cooling water, and a mixture of the cooling water and the hydraulic oil. It is roughly composed of a hydraulic oil heat exchanger 50 that exchanges heat, and an exhaust heat recovery device 60 that heats the cooling water with the heat of the exhaust gas of the engine 100 .

A discharge port of water pump 30 communicates with a water jacket (not shown) formed in engine 100 . In this water jacket, cooling water from the water pump 30 passes through the water jacket on the cylinder block side, is introduced into the water jacket on the cylinder head side, and then flows out to the conduit H2. Engine 100 is provided with a water temperature sensor 71 that detects the temperature of cooling water in engine 100 .

A conduit H2 extending from the engine 100 branches in two directions, a conduit H3 such as a hose and a conduit H4. The conduit H4 is connected to an upper tank 19 provided at the inlet of the radiator 17 . A lower tank 18 provided at the outlet of the radiator 17 is connected to a conduit H1. It flows into the water pump 30 .

The pipeline H3 is branched into a pipeline H7 connected to the inflow part of the heater core 40 and a pipeline H9 connected to the inflow part of the hydraulic oil heat exchanger 50 at the connection part J11. Further, the pipe line H8 connected to the outflow part of the heater core 40 and the pipe line H10 connected to the outflow part of the hydraulic oil heat exchanger 50 are connected to the pipe line H5 at the connection part J21. The pipe line H5 is connected to an inflow part (cooling water inlet 65 described later) of the exhaust heat recovery device 60 . A pipeline H6 is connected to an outflow portion (cooling water outlet 66 described later) of the exhaust heat recovery device 60, and the cooling water flowing out of the exhaust heat recovery device 60 is supplied to a pipeline H11 connected to the pipeline H6. flows into the water pump 30 via the

Thus, heater core 40 and hydraulic oil heat exchanger 50 are provided in parallel with engine 100 . Further, the exhaust heat recovery device 60 is provided in series with the engine 100 via the water pump 30 on the downstream side of the heater core 40 and the hydraulic oil heat exchanger 50 .

Here, a first circulation circuit C1 (pipes H2→H3→H7→H8→H5→H6→H11) causes the cooling water flowing out of the engine 100 to flow into the engine 100 via the heater core 40 and the exhaust heat recovery device 60. ), and a second circulation circuit C2 (pipe a flow path through which the cooling water passes, such as a path H2→H3→H9→H10→H5→H6→H11), and a third circulation circuit through which the cooling water flowing out from the engine 100 flows into the engine 100 via the radiator 17. C3 (a flow path through which cooling water passes, such as H2->H4->H1->H11) is defined.

A pipe line H7 connected to the upstream side of the heater core 40 is provided with a first control valve V1 for adjusting the flow rate of cooling water flowing into the heater core 40 in the first circulation circuit. Further, a pipe line H9 connected to the upstream side of the hydraulic oil heat exchanger 50 is provided with a second control valve V2 for adjusting the flow rate of cooling water flowing into the hydraulic oil heat exchanger 50 in the second circulation circuit. is provided.

A pipe line H1 connected to the downstream side of the radiator 17 is provided with a third control valve V3 that adjusts the flow rate of cooling water flowing out from the radiator 17 to the engine 100 side in the third circulation circuit. Further, on the downstream side of the third control valve V3 in the conduit H1, that is, on the side of the engine 100 and the water pump 30, there is provided between the radiator 17 of the third circulation circuit and the engine 100, and a cooling A thermostat valve 20 is provided to control the flow rate of cooling water flowing from the radiator 17 into the engine in accordance with the temperature of the water.

FIG. 3 is a partial cross-sectional view showing the configuration of the exhaust heat recovery device. 4 and 5 are diagrams showing an exhaust heat recovery device installed in an exhaust gas flow path of an engine together with its peripheral configuration.

As shown in FIG. 3, the exhaust heat recovery device 60 is laminated with a substantially uniform clearance via spacers (not shown), or is a flat tube having a plurality of convex dowels protruding from its surface. 61, a tube assembly 64 formed by overlapping the dowels of the flat tubes 61 to keep the clearance between the flat tubes 61 substantially uniform and assembling the ends to the end plates 63 respectively, and a shell accommodating the tube assembly 64. 60a. A cooling water inlet 65 is provided at one end of the bottom surface or side surface of the shell 60a, and a cooling water outlet 66 is provided at the end opposite to the cooling water inlet 65 on the top surface or side surface. Exhaust gas from the engine 100 passes through the shell 60 a of the exhaust heat recovery device 60 , thereby exchanging heat with cooling water flowing through the laminated flat tubes 61 .

As shown in FIGS. 4 and 5, the exhaust heat recovery device 60 is arranged on one side of the exhaust gas flow path that branches into two and merges. A switching valve 200 for selectively switching the flow path of the exhaust gas to one of the two branched flow paths, and the switching valve 200 based on a flow path switching signal from the ECU 300, which is a control device, are provided in the portion where the exhaust gas joins. A switching actuator 200a is arranged. The switching valve 200 is normally in an open state, as shown in FIG. 4, so that exhaust gas does not pass through the exhaust heat recovery device 60. Further, after the engine 100 is started, when the temperature of the cooling water is below a certain temperature (for example, 0° C.), the ECU 300 sends a flow path switching signal command to the actuator 200a, and as shown in FIG. The valve 200 is fully closed, that is, the exhaust gas passes through the exhaust heat recovery device 60 . In this state, the energy of the exhaust gas is recovered by the exhaust heat recovery device 60, and the recovered energy quickly raises the temperature of the cooling water.

FIG. 6 is a diagram showing the relationship with other configurations of the ECU, which is the control device. Also, FIG. 7 is a functional block diagram showing the processing contents of the ECU.

As shown in FIG. 6, the ECU 300, which is a control device, includes an outside air temperature sensor 70 that detects the outside air temperature, a water temperature sensor 71 that detects the temperature of cooling water for the engine 100, which will be described later, and a room temperature sensor that detects the temperature inside the cab 9. Based on input signals from sensors such as the sensor 72, the oil temperature sensor 73 that detects the temperature of the hydraulic oil stored in the hydraulic oil tank 102, and the operation amount sensor 74 that detects the operation amount of the operation device, the second By controlling the one control valve V1, the second control valve V2, the third control valve V3, and the actuator 200a of the switching valve 200, the operation of the cooling water circulation system is controlled.

As shown in FIG. 7, the ECU 300 compares the detection result from the outside air temperature sensor 70 with a predetermined reference temperature, and outputs the comparison result to the control unit 300f. A water temperature comparison unit 300b that compares the detection result with a predetermined reference temperature and outputs the comparison result to a control unit 300f, and a detection result from the room temperature sensor 72 with the predetermined reference temperature to control the comparison result. a room temperature comparison unit 300c that outputs to the unit 300f; an oil temperature comparison unit 300d that compares the detection result from the oil temperature sensor 73 with a predetermined reference temperature and outputs the comparison result to the control unit 300f; A manipulated variable comparison unit 300e that compares the detection result from and a predetermined reference manipulated variable and outputs the comparison result to the control unit 300f, an outside air temperature comparison unit 300a, a water temperature comparison unit 300b, a room temperature comparison unit 300c, an oil temperature Opening degree control signals for controlling the first control valve V1, the second control valve V2, and the third control valve V3 based on the comparison results input from the comparison unit 300d and the manipulated variable comparison unit 300e. , and a control unit 300f for calculating and outputting a channel switching signal for controlling the actuator 200a.

FIG. 8 is a flow chart showing the control contents of the cooling water circulation system by the ECU, and FIG. 9 is a diagram showing how the first to third control valves are switched between open and closed states. 10 and 11 are diagrams showing how the cooling water flow path is switched in the cooling water circulation device.

As shown in FIG. 8, first, when the engine 100 is started, the ECU 300 reads the detection result of the outside air temperature sensor 70 (step S100). −5° C.) or less (step S110).

If the determination result in step S110 is NO, as shown in FIG. 9, the first control valve V1 and the second control valve V2 are controlled to be fully closed, and the third control valve V3 is fully opened. state (step S111). At this time, the cooling water in the cooling water circulation system circulates through the third circulation circuit C3 that flows through the radiator 17 .

Further, if the determination result in step S110 is YES, that is, if the outside air temperature is low (for example, in winter), the detection result of the room temperature sensor 72 is read (step S120), and the room temperature of the cab 9 is It is determined whether or not the temperature is below a predetermined reference temperature T2 (for example, 20° C.) (step S130). At this time, the ECU 300 reads the detection result of the water temperature sensor 71 and finds that the temperature of the cooling water is below a predetermined reference temperature (the temperature at which the room temperature becomes 20° C., for example, 60° C.). It is determined at the same time whether

If the determination result in step S130 is YES, as shown in FIG. 9, the first control valve V1 is controlled to be fully open, and the second control valve V2 and the third control valve V3 are fully closed. state (step S131), and the processes of steps S130 and S131 are repeated until the determination result of step S130 becomes NO. In step S131, as shown in FIG. 10, the cooling water in the cooling water circulation device circulates through the first circulation circuit C1. As a result, the cooling water whose temperature is raised by the heat recovered from the exhaust gas of the engine 100 by the exhaust heat recovery device 60 is distributed to the heater core 40 and used to raise the indoor temperature. Further, at this time, since the temperature rise of the room temperature is prioritized, cooling water is not distributed to the hydraulic oil heat exchanger 50, and the temperature of the hydraulic oil in the hydraulic oil heat exchanger 50 is not increased.

Further, if the determination result in step S130 is NO, that is, if the room temperature is higher than the reference temperature (or if the cooling water temperature is higher than the reference temperature), the oil temperature sensor 73 is read (step S140), and it is determined whether or not the temperature of the hydraulic oil is equal to or higher than a predetermined reference temperature T3 (eg, 60° C.) (step S150).

If the determination result in step S150 is NO, as shown in FIG. 9, the first control valve V1 is controlled to a half-open state (for example, a half-open state), and the second control valve V2 is opened. The control valve V3 is fully opened and the third control valve V3 is fully closed (step S151), and steps S150 and S151 are repeated until the determination result in step S150 becomes YES. In step S151, the first control valve V1 is controlled to be half-opened, so the recovered heat capacity distributed to the heater core 40 is reduced. Further, since the second control valve V2 is controlled to be fully open, the cooling water in the cooling water circulation system mainly circulates through the second circulation circuit C2 as shown in FIG.

At this time, since the first control valve V1 is controlled to be half open or less, the heater core 40 of the cooling water whose temperature is raised in the exhaust heat recovery device 60 by the heat recovered from the exhaust gas of the engine 100 and the hydraulic oil heat exchanger 50 , the flow rate to the hydraulic heat exchanger 50 is greater than the flow rate to the heater core 40 . That is, since the cooling water flows through the hydraulic oil heat exchanger 50, the temperature of the hydraulic oil is raised by the thermal energy recovered by the cooling water from the exhaust gas. Further, since the cooling water does not flow through the radiator 17 by controlling the third control valve V3 to the fully closed state, the cooling water is cooled by the radiator 17, that is, the heat energy of the cooling water is transferred to the radiator. Since the discharge at 17 is suppressed, higher temperature cooling water flows through the hydraulic oil heat exchanger 50, and the hydraulic oil can be heated more quickly.

If the determination result in step S150 is YES, as shown in FIG. 9, the first control valve V1 is set to a half-open state (for example, a quarter-open state lower than the opening degree in step S151). In addition, the second control valve V2 and the third control valve V3 are fully opened (step S160), and the process ends. When the temperature of the hydraulic oil rises above a predetermined temperature, oxidation is accelerated, resulting in deterioration of performance. Therefore, in the present embodiment, when the detected value of the oil temperature sensor 73 installed in the hydraulic oil tank 102 is equal to or higher than a predetermined reference temperature T3 (for example, 60° C.), the second control valve V2 is controlled to be fully closed to block the flow of cooling water into the hydraulic oil heat exchanger 50, so that the temperature of the hydraulic oil can be prevented from rising too much.

FIG. 12 is a diagram showing changes in the degree of opening of the third control valve together with changes in the degree of opening of the thermostat valve. FIG. 13 is a diagram showing a comparison of changes in the temperature of cooling water and hydraulic oil and changes in the degree of opening of the third control valve.

As shown in FIGS. 12 and 13, the degree of opening of the third control valve V3 is controlled by the ECU 300 according to the temperature of the cooling water. As shown in FIG. 12, the temperature at which the third control valve V3 starts to change from the fully closed state to the half open state is set to be higher than the temperature at which the thermostat valve 20 starts to change from the fully closed state to the half open state. there is By controlling the degree of opening of the third control valve V3 in this way, heat radiation from the cooling water by the radiator 17 is suppressed to suppress a decrease in the temperature of the cooling water. Since cooling water having a higher temperature than in the case of controlling the flow rate of is allowed to flow through the hydraulic oil heat exchanger 50, the heat exchange capacity can be maximized, and the temperature of the hydraulic oil can be quickly increased.

The temperature characteristic of the degree of opening of the thermostat valve 20 is determined, for example, from the relationship between the temperature of the engine 100 (that is, the temperature of the cooling water) and the fuel consumption. When controlling , the temperature of the cooling water is controlled with emphasis on fuel efficiency, and regardless of the temperature rise state of the hydraulic oil in the hydraulic oil heat exchanger 50 using the thermal energy of the cooling water, That is, even if the temperature of the hydraulic oil is not sufficiently raised, the radiator 17 dissipates heat from the cooling water. This leads to a decrease in efficiency from the viewpoint of temperature rise of the hydraulic oil. Therefore, in the present embodiment, the temperature of the third control valve V3 is higher than that of the thermostat valve 20, and the degree of opening of the third control valve V3 is increased. It is configured to allow water to flow through the hydraulic oil heat exchanger 50 . However, the temperature characteristics of the degree of opening of the third control valve V3 with respect to the temperature characteristics of the degree of opening of the thermostat valve 20 are in a range in which fuel consumption does not decrease due to an increase in the temperature of the cooling water (that is, an increase in the temperature of the engine 100). Alternatively, it is set in a range in which the improvement in work efficiency due to the improvement in operability of the working machine due to the early temperature rise of the hydraulic oil exceeds the decrease in efficiency due to a slight decrease in fuel consumption.

The reference temperature T4 at which the third control valve V3 begins to change from the fully closed state to the half-open state is an appropriate temperature (eg, 95° C.) below the warning temperature (eg, 100° C.) at which the engine 100 does not overheat. and so on. As shown in FIG. 13, when the engine 100 is started, the coolant temperature rises earlier than the working oil temperature. At this time, the third control valve V3 is fully closed. Then, by flowing high-temperature cooling water through the hydraulic oil heat exchanger 50, the temperature of the hydraulic oil rises, and when it reaches a predetermined temperature (reference temperature T3), the third control valve V3 is controlled to a fully open state. high-temperature cooling water to flow through the radiator 17. As a result, the temperature of the cooling water can be lowered, and overheating of the engine 100 can be prevented.

Effects of the present embodiment configured as above will be described.

In the prior art, there is a technique related to automobiles that improves the overall energy efficiency by reusing the thermal energy of the exhaust gas that has not been used. However, although the conventional technology is optimized for a small amount of hydraulic oil, such as the usage conditions in automobiles, it is suitable for rapid temperature rise of the hydraulic oil when using a large amount of hydraulic oil, such as in working machines. There was room for improvement in energy efficiency when applied to work machines, rather than being a technology that was easy to use.

On the other hand, in the present embodiment, an engine 100, a hydraulic pump 101 driven by the engine 100, and hydraulic actuators (boom cylinder 12, arm cylinder 14) driven by hydraulic fluid discharged from the hydraulic pump 101 , a bucket cylinder 16), a hydraulic oil tank 102 that stores hydraulic oil, a radiator 17 that cools the cooling water that cools the engine 100, and a heater core 40 that heats the air sent to the cab 9 by the heat of the cooling water. , an outside air temperature sensor 70 that detects the outside air temperature, a hydraulic oil heat exchanger 50 that exchanges heat between the cooling water and the hydraulic oil, and an exhaust heat recovery device 60 that heats the cooling water with the heat of the exhaust gas of the engine 100. , a first circulation circuit C1 for flowing cooling water flowing out of the engine 100 into the engine 100 via the heater core 40 and the exhaust heat recovery device 60, and a hydraulic oil heat exchanger 50 for flowing cooling water flowing out of the engine 100. a second circulation circuit C2 that flows into the engine via an exhaust heat recovery device 60; A water temperature sensor 71 that detects the temperature of the cooling water inside, a first control valve V1 that adjusts the flow rate of the cooling water flowing into the heater core 40 in the first circulation circuit C1, and a hydraulic oil in the second circulation circuit C2 A second control valve V2 for adjusting the flow rate of cooling water flowing into the heat exchanger 50, and a third control valve V3 for adjusting the flow rate of cooling water flowing into the engine 100 from the radiator 17 in the third circulation circuit C3. and the ECU 300 that controls the opening degrees of the first to third control valves V1 to V3 to adjust the flow rate of the cooling water, and the radiator 17 of the third circulation circuit C3 and the engine 100. , and a thermostat valve 20 for controlling the flow rate of cooling water flowing into the engine 100 from the radiator 17 according to the temperature of the flowing cooling water. The temperature of the coolant when the ECU 300 controls the opening of the third control valve V3 and controls the third control valve V3 from the closed state to the open state when the detection result of the outside air temperature sensor 70 is equal to or lower than a predetermined reference temperature. is higher than the temperature when the thermostat valve 20 changes from the closed state to the open state, energy efficiency can be improved, and the temperature of the hydraulic oil can be raised early.

That is, according to the present embodiment, the cooling water whose temperature is raised by the heat recovered from the exhaust gas of the engine by the exhaust heat recovery device is used according to the operation status of the construction machine, and the hot water circulation circuit is appropriately switched. , it is possible to quickly raise the temperature of the hydraulic oil for the hydraulic pump while maintaining the heating performance in the cab. Therefore, it is possible to improve the energy efficiency of the working machine as a whole, including fuel consumption.

Further, since the temperature of the hydraulic oil is raised by the thermal energy of the cooling water, the temperature of the hydraulic oil can be raised early, and the operability of the work machine can be improved. In particular, when the outside air temperature is low and the temperature of the hydraulic oil is expected to be lower, heat radiation from the cooling water by the radiator 17 is suppressed to suppress a drop in the temperature of the cooling water, so the operation is more efficient. Early heating of the oil can be performed.

<Modification>
The opening/closing control of the first to third control valves V1 to V3 shown in this embodiment can be modified as follows.

FIG. 10 is a diagram showing how the open/closed states of the first to third control valves according to this modification are switched.

In the second circulation circuit C<b>2 , the cooling water flowing out of the engine 100 flows into the engine 100 via the hydraulic oil heat exchanger 50 . By flowing high-temperature cooling water through the hydraulic oil heat exchanger 50, the hydraulic oil temperature rises, and when it reaches a predetermined temperature T5 (for example, 25° C.), the operation device is operated based on the detection result of the operation amount sensor 74. The state is determined, and if the operation state is equal to or lower than the half lever, the second control valve V2 is controlled to be fully open, and the third control valve V3 is controlled to be fully closed. Further, if the operation state of the operating device is the full lever, the second control valve V2 is controlled to be fully closed, and the third control valve V3 is controlled to be fully open. This control can prevent an excessive rise in hydraulic oil due to the addition of throttle energy on the hydraulic system due to full lever operation. Further, it is possible to prevent a sudden increase in the coolant level due to a sudden increase in the engine load due to full lever operation, and prevent overheating of the engine 100 .

Next, features of each of the above embodiments will be described.

(1) In the above embodiment, the engine 100, the hydraulic pump 101 driven by the engine, and the hydraulic actuators (for example, the boom cylinder 12 and the arm cylinder 14) driven by hydraulic fluid discharged from the hydraulic pump , bucket cylinder 16), a hydraulic oil tank 102 that stores the hydraulic oil, a radiator 17 that cools the cooling water that cools the engine, and the air sent to the cab (for example, the cab 9) to the cooling water. A heater core 40 that heats with heat, an outside air temperature sensor 70 that detects the outside air temperature, a hydraulic oil heat exchanger 50 that exchanges heat between the cooling water and the hydraulic oil, and the heat of the exhaust gas of the engine. an exhaust heat recovery device 60 for heating cooling water; a first circulation circuit C1 for causing the cooling water flowing out of the engine to flow into the engine via the heater core and the exhaust heat recovery device; a second circulation circuit C2 for allowing the outflowing cooling water to flow into the engine via the hydraulic oil heat exchanger and the exhaust heat recovery device; A third circulation circuit C3 that flows into the engine, a water temperature sensor 71 that detects the temperature of the cooling water in the engine, and a third circulation circuit that adjusts the flow rate of the cooling water that flows into the heater core in the first circulation circuit. 1 control valve V1, a second control valve V2 for adjusting the flow rate of the cooling water flowing into the hydraulic oil heat exchanger in the second circulation circuit, and opening of the first and second control valves A control device (e.g., ECU 300) that adjusts the flow rate of the cooling water by controlling the temperature of the cooling water, and the temperature of the cooling water that is provided between the radiator and the engine in the third circulation circuit. and a thermostat valve 20 for controlling the flow rate of the cooling water flowing from the radiator to the engine according to A third control valve V3 is provided for adjusting the flow rate of the cooling water, and the control device closes the third control valve when the detection result of the outside air temperature sensor is equal to or lower than a predetermined reference temperature. The temperature of the cooling water when the thermostat valve is controlled from the closed state to the open state is higher than the temperature of the cooling water when the thermostat valve is changed from the closed state to the open state, according to the detection result of the water temperature sensor. The opening of the control valve was controlled.

As a result, energy efficiency can be improved, and the temperature of the hydraulic oil can be raised early.

(2) In the above-described embodiment, in the working machine of (1), the control device (for example, the ECU 300) controls, when the detection result of the water temperature sensor 71 is below a predetermined switching temperature, The second control valve V2 is controlled to be closed while controlling the first control valve V1 to be open, and when the detection result of the water temperature sensor is higher than the switching temperature, the first control valve is controlled to be closed while the second control valve is controlled to be opened.

(3) In the above embodiment, the work machine of (2) includes an oil temperature sensor 73 that detects the temperature of the hydraulic oil stored in the hydraulic oil tank 102, and the control device (for example, The ECU 300 controls the first control valve V1 to a half -open state when the detection result of the oil temperature sensor is below a predetermined temperature.

(4) In the above embodiment, in the work machine of (2), the control device (e.g., ECU 300) operates the hydraulic actuators (e.g., boom cylinder 12, arm cylinder 14, bucket cylinder 16). The degree of opening of the second control valve V2 is controlled according to the detection result of an operation amount sensor 74 that detects the amount of operation of the operating device for controlling.

<Appendix>
It should be noted that the present invention is not limited to the above-described embodiments, and includes various modifications and combinations within the scope of the invention. Moreover, the present invention is not limited to those having all the configurations described in the above embodiments, and includes those having some of the configurations omitted. Further, each of the above configurations, functions, etc. may be realized by designing a part or all of them, for example, with an integrated circuit. Moreover, each of the above configurations, functions, etc. may be realized by software by a processor interpreting and executing a program for realizing each function.

DESCRIPTION OF SYMBOLS 1... Lower running body 2... Upper revolving body 3... Front device 4... Crawler frame 5... Crawler 7... Traveling motor 8... Revolving frame 9... Cab 10... Machine room 11... Boom 12 Boom cylinder 13 Arm 14 Arm cylinder 15 Bucket 16 Bucket cylinder 17 Radiator 18 Lower tank 19 Upper tank 20 Thermostat valve 30 Water pump 40 Heater core 50 Hydraulic oil heat exchanger 60 Exhaust heat recovery device 60a Shell 61 Flat tube 63 End plate 64 Tube assembly 65 Cooling water inlet 66 Cooling water outlet 70 Outside air temperature sensor 71 Water temperature sensor 72 Room temperature sensor 73 Oil temperature sensor 74 Operation amount sensor 100 Engine 101 Hydraulic pump 102 Hydraulic oil tank 200 Switching valve 200a Actuator 300 ECU ( control device), 300a outside air temperature comparison unit 300b water temperature comparison unit 300c room temperature comparison unit 300d oil temperature comparison unit 300e manipulated variable comparison unit 300f control unit C1 first circulation circuit, C2... second circulation circuit, C3... third circulation circuit, H1 to H11... pipeline, V1... first control valve, V2... second control valve, V3... third control valve

Claims (4)

engine and
a hydraulic pump driven by the engine;
a hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump;
a hydraulic oil tank that stores the hydraulic oil;
a radiator for cooling cooling water for cooling the engine;
a heater core that heats the air sent to the cab by the heat of the cooling water;
an outside air temperature sensor that detects the outside air temperature;
a hydraulic oil heat exchanger that exchanges heat between the cooling water and the hydraulic oil;
an exhaust heat recovery device that heats the cooling water with the heat of the exhaust gas of the engine;
a first circulation circuit that causes the cooling water that has flowed out of the engine to flow into the engine through the heater core and the exhaust heat recovery device;
a second circulation circuit that causes the cooling water that has flowed out of the engine to flow into the engine via the hydraulic oil heat exchanger and the exhaust heat recovery device;
a third circulation circuit that causes the cooling water that has flowed out of the engine to flow into the engine via the radiator;
a water temperature sensor that detects the temperature of the cooling water in the engine;
a first control valve that adjusts the flow rate of the cooling water flowing into the heater core in the first circulation circuit;
a second control valve that adjusts the flow rate of the cooling water flowing into the hydraulic oil heat exchanger in the second circulation circuit;
a control device that controls the opening degrees of the first and second control valves to adjust the flow rate of the cooling water;
a thermostat valve provided between the radiator and the engine in the third circulation circuit for controlling the flow rate of the cooling water flowing from the radiator into the engine according to the temperature of the flowing cooling water; In a working machine equipped with
A third control valve that adjusts the flow rate of the cooling water flowing into the engine from the radiator in the third circulation circuit through the thermostat valve,
When the detection result of the outside air temperature sensor is equal to or lower than a predetermined reference temperature, the control device controls the temperature at which the third control valve is controlled from the closed state to the open state so that the thermostat valve is closed. A working machine, wherein the degree of opening of the third control valve is controlled according to the detection result of the water temperature sensor so that the temperature of the cooling water becomes higher than the temperature of the cooling water when the working machine changes from the state to the open state. The work machine according to claim 1,
When the detection result of the water temperature sensor is equal to or lower than a predetermined switching temperature, the control device controls the first control valve to open and the second control valve to close. A working machine according to claim 1, wherein, when the detection result of a water temperature sensor is higher than the switching temperature, the first control valve is controlled to be closed and the second control valve is controlled to be opened. The work machine according to claim 2,
An oil temperature sensor that detects the temperature of the hydraulic oil stored in the hydraulic oil tank,
The working machine, wherein the control device controls the first control valve to a half-open state when the detection result of the oil temperature sensor is equal to or lower than a predetermined temperature. The work machine according to claim 2,
The working machine, wherein the control device controls the degree of opening of the second control valve according to a detection result of an operation amount sensor that detects an operation amount of an operation device for operating the hydraulic actuator.

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