JP2020133521A - Work machine - Google Patents

Abstract

To provide a work machine capable of improving energy efficiency and early increasing a temperature of hydraulic oil.SOLUTION: A work machine comprises: a third circulation circuit C3 which allows cooling water from an engine 100 to flow back into the engine 100 through a radiator 17; a third control valve V3 which regulates a flow rate of the cooling water flowing from the radiator 17 into the engine 100 in the third circulation circuit C3; and a thermostat valve 20 which controls the flow rate of the cooling water flowing from the radiator 17 into the engine 100 in accordance with a temperature of the cooling water distributed between the radiator 17 and the engine 100 in the third circulation circuit C3. In the case where an external temperature is equal to or lower than a reference temperature, an ECU 300 controls an opening of the third control valve V3 in accordance with a detection result of a water temperature sensor 71 so that the temperature of the cooling water when controlling the third control valve V3 from a closed state to an open state becomes higher than the temperature of the cooling water when the thermostat valve 20 is operated from the closed state to the open state.SELECTED DRAWING: Figure 12

Description

The present invention relates to a working machine.

The viscosity of hydraulic oil, which is the driving medium of work machines such as hydraulic excavators, changes significantly with changes in temperature. For example, when the hydraulic oil is at a low temperature, the viscosity becomes high and the fluidity is poor, so that the responsiveness of the hydraulic equipment deteriorates and the load increases. Further, since the engine mounted on the work machine (for example, a diesel engine) is connected to the hydraulic pump, when the viscosity of the hydraulic oil is high, the applied load causes deterioration of the work fuel consumption. Therefore, it is important to raise the temperature of the hydraulic oil at an early stage to reduce the viscosity immediately after starting the work machine. On the other hand, considering the case where the thermal energy of the exhaust gas of the engine is directly discarded in the atmosphere, in the case of a diesel engine, the effective energy efficiency is considerably low at about 40% even at the upper limit.

Therefore, it is considered that the heat energy of the exhaust gas of the engine is recovered by a heat exchanger and reused for early temperature rise of the transmission hydraulic oil. For example, in Patent Document 1, the cooling flowed out from the engine is described. A first circulation circuit for allowing water to flow into the engine via the heater core, and a second circulation circuit for allowing the cooling water flowing out of the engine to flow into the engine via 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 are provided, and the circulation circuit is selected according to the situation. A cooling water circulation device is disclosed.

Patent No. 4998390

In the above-mentioned conventional technique, the overall energy efficiency can be improved by reusing the thermal energy of the exhaust gas that has not been used. However, although the above-mentioned conventional technique is a technique optimized for a small amount of hydraulic oil such as the conditions of use in an automobile, it is suitable for early temperature rise of the hydraulic oil when a large amount of hydraulic oil is used such as a work machine. There was room for improvement in energy efficiency when applied to work machines rather than technology.

The present invention has been made in view of the above, and an object of the present invention is to provide a working machine capable of improving energy efficiency and raising the temperature of hydraulic oil at an early stage.

The present application includes a plurality of means for solving the above problems, and to give an example thereof, an engine, a hydraulic pump driven by the engine, and a hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump. The hydraulic oil tank for storing the hydraulic oil, the radiator for cooling the cooling water for cooling the engine, the heater core for heating the air sent to the cab with the heat of the cooling water, and the outside air temperature are detected. An outside 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 by the heat of the exhaust gas of the engine, and an outflow from the engine. A first circulation circuit that allows the cooling water to flow into the engine via the heater core and the exhaust heat recovery device, and the hydraulic oil heat exchanger and the exhaust heat recovery device that flow out the cooling water from the engine. A second circulation circuit that flows into the engine via the above, a third circulation circuit that causes the cooling water that has flowed out of the engine to flow into the engine via the radiator, and the cooling water in the engine. A water temperature sensor that detects the temperature, a first control valve that adjusts the flow rate of the cooling water that flows into the heater core in the first circulation circuit, and a hydraulic oil heat exchanger that flows into the 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 controls the opening degree of the first to third control valves to adjust the flow rate of the cooling water, and the third circulation. In a work machine provided between the radiator of the circuit and the engine and provided with a thermostat valve for controlling the flow rate of the cooling water flowing into the engine from the radiator according to the temperature of the cooling water flowing through the circuit. The control device includes a third control valve that adjusts the flow rate of the cooling water that flows into the engine from the radiator in the third circulation circuit via the thermostat valve, and the control device is a detection result of the outside temperature sensor. When is equal to or lower than a predetermined reference temperature, the temperature at which the third control valve is controlled from the closed state to the open state is higher than the temperature at which the thermostat valve is changed from the closed state to the open state. It is assumed that the opening degree 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.

According to the present invention, energy efficiency can be improved and the hydraulic oil can be heated at an early stage.

It is a side view which shows the hydraulic excavator which is an example of the work machine provided with the cooling water circulation device which concerns on one Embodiment. It is a figure which shows typically the example of the cooling water circulation device mounted on the work machine by extracting with the related structure. It is a partial cross-sectional view which shows the structure of the exhaust heat recovery device. It is a figure which shows the exhaust heat recovery device installed in the exhaust gas flow path of an engine together with the peripheral composition. It is a figure which shows the exhaust heat recovery device installed in the exhaust gas flow path of an engine together with the peripheral composition. It is a figure which shows the relationship with other configurations of the ECU which is a control device. It is a functional block diagram which shows the processing content of an ECU. It is a flowchart which shows the control content of the cooling water circulation device by an ECU. It is a figure which shows the state of switching of the open / closed state of the 1st to 3rd control valves. It is a figure which shows the state of switching of the flow path of cooling water in a cooling water circulation device. It is a figure which shows the state of switching of the flow path of cooling water in a cooling water circulation device. It is a figure which shows the change of the opening degree of the 3rd control valve together with the change of the opening degree of a thermostat valve. It is a figure which compares and shows the temperature change of the cooling water and the hydraulic oil, and the change of the opening degree of the third control valve. It is a figure which shows the state of switching of the open / closed state of the 1st to 3rd control valves which concerns on a modification.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 14. In the present embodiment, a hydraulic excavator will be described as an example of a work machine, but another cooling water circulation device having a configuration in which the cooling water of the engine is heated by the heat recovered from the exhaust gas of the engine will be described. 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 work machine provided with a cooling water circulation device according to the present embodiment. Further, FIG. 2 is a diagram schematically showing an example of a cooling water circulation device mounted on a work machine, together with related configurations.

In FIG. 1, the hydraulic excavator is composed of a lower traveling body 1 and an upper swivel body 2 constituting the vehicle body, and a front device 3 is undulatingly mounted on the front portion of the upper swivel body 2.

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), and the crawlers 5 on both sides are individually rotationally driven by the left and right traveling motors 7 (only one is shown). Run.

The upper swivel body 2 is provided on the lower traveling body 1 so as to be swivelable, and is composed of a swivel frame 8, a cab 9 as an cab, a machine room 10, and the like. The cab 9 has a substantially sealed structure that is shielded from the outside air in order to protect the driver from external noise and dust. In addition to an air conditioner (air conditioner) to ensure its comfort, the operator A key switch for operating the start / stop of the hydraulic excavator (that is, start / stop of the engine 100 described later), a hydraulic actuator of the front device 3 (boom cylinder 12, arm cylinder 14, bucket cylinder 16), etc. It is equipped with an operating device (not shown) for operating the cylinder.

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

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

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

In FIG. 2, the cooling water circulation device includes a radiator 17 that cools the cooling water that cools the engine 100, a heater core 40 that heats the air sent into the cab 9 by the heat of the cooling water, and cooling water and 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 by the heat of the exhaust gas of the engine 100.

The discharge port of the water pump 30 communicates with a water jacket (not shown) formed on the engine 100. In this water jacket, the 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 pipeline H2. The engine 100 is provided with a water temperature sensor 71 that detects the temperature of the cooling water in the engine 100.

The pipeline H2 extending from the engine 100 is branched in two directions, a pipeline H3 such as a hose and a pipeline H4. The pipeline H4 is connected to an upper tank 19 provided in the inflow portion of the radiator 17. Further, the pipe line H1 is connected from the lower tank 18 provided in the outflow portion of the radiator 17, and the cooling water flowing out from the radiator 17 to the pipe line H1 passes through the pipe line H11 connected to the pipe line H1. It flows into the water pump 30.

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

As described above, the heater core 40 and the hydraulic oil heat exchanger 50 are provided in parallel with the 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, the first circulation circuit C1 (pipeline H2 → H3 → H7 → H8 → H5 → H6 → H11) that 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. A second circulation circuit C2 (tube) that allows the cooling water flowing out of the engine 100 to flow into the engine 100 via the hydraulic oil heat exchanger 50 and the exhaust heat recovery device 60. Road H2 → H3 → H9 → H10 → H5 → H6 → H11) and a third circulation circuit that allows the cooling water flowing out of the engine 100 to flow into the engine 100 via the radiator 17. C3 (flow path through which cooling water passes, such as pipeline H2 → H4 → H1 → H11) is defined.

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

A third control valve V3 for adjusting the flow rate of the cooling water flowing out from the radiator 17 to the engine 100 side in the third circulation circuit is arranged in the pipeline H1 connected to the downstream side of the radiator 17. Further, on the downstream side of the third control valve V3 of the pipeline H1, that is, on the engine 100 and the water pump 30 side, cooling provided between the radiator 17 of the third circulation circuit and the engine 100 to pass through. A thermostat valve 20 is provided to control the flow rate of the cooling water flowing into the engine from the radiator 17 according to the temperature of the water.

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

As shown in FIG. 3, the exhaust heat recovery device 60 is a flat tube in which the exhaust heat recovery device 60 is laminated with a substantially uniform clearance via a spacer (not shown), or a plurality of convex dowels are projected on the surface. A tube assembly 64 formed by superimposing the dowels of the flat tube 61 and the dowels of the flat tube 61 and assembling the ends to the end plate 63 while maintaining a substantially uniform clearance between the flat tubes 61, and a shell for accommodating the tube assembly 64. It is formed by 60a. A cooling water inlet 65 is provided at one end of the lower surface or the 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 upper surface or the side surface. When the exhaust gas of the engine 100 passes through the inside of the shell 60a of the exhaust heat recovery device 60, heat exchange is performed with the cooling water flowing through the laminated flat tubes 61.

As shown in FIGS. 4 and 5, the exhaust heat recovery device 60 is arranged in one of the flow paths of the exhaust gas that branches into two and merges. At the junction of the exhaust gas, a switching valve 200 that selectively switches the flow path of the exhaust gas to one of the two branching flow paths and a switching valve 200 based on the flow path switching signal from the ECU 300 that is the control device are provided. An actuator 200a for switching is arranged. The switching valve 200 is normally in an open state as shown in FIG. 4, and is in a state in which the 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 to switch the cooling water 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 is used to raise the temperature of the cooling water at an early stage.

FIG. 6 is a diagram showing a relationship with other configurations of an ECU which is a control device. Further, 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, has an outside temperature sensor 70 that detects the outside air temperature, a water temperature sensor 71 that detects the temperature of the cooling water of the engine 100 described later, and a room temperature that detects the temperature inside the cab 9. Based on the 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 operating amount sensor 74 that detects the operating amount of the operating device, the first The operation of the cooling water circulation device is controlled by controlling the control valve V1, the second control valve V2, the third control valve V3, and the actuator 200a of the switching valve 200.

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 from the outside air temperature comparison unit 300a and the water temperature sensor 71. The detection result is compared with the predetermined reference temperature, the water temperature comparison unit 300b that outputs the comparison result to the control unit 300f, the detection result from the room temperature sensor 72 and the predetermined reference temperature are compared, and the comparison result is controlled. The room temperature comparison unit 300c output to the unit 300f compares the detection result from the oil temperature sensor 73 with a predetermined reference temperature, and the oil temperature comparison unit 300d outputs the comparison result to the control unit 300f, and the operation amount sensor 74. The operation amount comparison unit 300e that compares the detection result from the above and the predetermined reference operation amount and outputs the comparison result to the control unit 300f, the outside air temperature comparison unit 300a, the water temperature comparison unit 300b, the room temperature comparison unit 300c, and the oil temperature. An opening control signal that controls 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 operation amount comparison unit 300e. It also has a control unit 300f that calculates and outputs a flow path switching signal that controls the actuator 200a.

FIG. 8 is a flowchart showing the control contents of the cooling water circulation device by the ECU, and FIG. 9 is a diagram showing a state of switching the open / closed state of the first to third control valves. Further, FIGS. 10 and 11 are diagrams showing a state of switching of the cooling water flow path in the cooling water circulation device.

As shown in FIG. 8, when the engine 100 is started, the ECU 300 first reads the detection result of the outside air temperature sensor 70 (step S100), and the outside air temperature is a predetermined reference temperature T1 (for example, as in winter). It is determined whether or not the temperature is -5 ° C. or lower (step S110).

When 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. It is controlled to the state (step S111). At this time, the cooling water in the cooling water circulation device circulates in the third circulation circuit C3 passing through the radiator 17.

Further, when the determination result in step S110 is YES, that is, when 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 changed. It is determined in advance whether or not the reference temperature is T2 (for example, 20 ° C.) or less (step S130). At this time, the ECU 300 reads the detection result of the water temperature sensor 71, and the temperature of the cooling water is equal to or lower than a predetermined reference temperature (the temperature at which the room temperature becomes 20 ° C., for example, 60 ° C.). Whether or not it is judged at the same time.

When the determination result in step S130 is YES, as shown in FIG. 9, the first control valve V1 is controlled to the fully open state, and the second control valve V2 and the third control valve V3 are fully closed. The state is controlled (step S131), and the processes of steps S130 and S131 are repeated until the determination result in step S130 becomes NO. In step S131, as shown in FIG. 10, the cooling water in the cooling water circulation device circulates in the first circulation circuit C1. As a result, the cooling water whose water 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 for raising the room temperature. Further, at this time, since the temperature rise of the room temperature is prioritized, the cooling water is not distributed to the hydraulic oil heat exchanger 50, and the hydraulic oil is not raised in the hydraulic oil heat exchanger 50.

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

When the determination result in step S150 is NO, as shown in FIG. 9, the first control valve V1 is controlled to the half-open state (for example, the 1/2 open state), and the second control valve V2 is set. The fully open state and the third control valve V3 are controlled to the fully closed state (step S151), and the processes of steps S150 and S151 are repeated until the determination result in step S150 becomes YES. In step S151, since the first control valve V1 is controlled in the half-open state, the recovered heat capacity distributed to the heater core 40 is reduced. Further, since the second control valve V2 is controlled to be in the fully open state, the cooling water in the cooling water circulation device mainly circulates in the second circulation circuit C2 as shown in FIG.

At this time, since the first control valve V1 is controlled to the half-open state or less, the heater core 40 of the cooling water and the hydraulic oil heat exchanger whose temperature has been raised by the exhaust heat recovery device 60 by the heat recovered from the exhaust gas of the engine 100. As for the distribution ratio flowing into the 50, the flow rate to the hydraulic oil heat exchanger 50 is larger than the flow rate of 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 heat energy recovered from the exhaust gas to the cooling water. Further, since the third control valve V3 is controlled to the fully closed state, the cooling water does not flow through the radiator 17, so that the cooling water is cooled by the radiator 17, that is, the thermal energy of the cooling water is the radiator. Since the release at 17 is suppressed, the cooling water having a higher temperature is passed through the hydraulic oil heat exchanger 50, and the temperature of the hydraulic oil can be raised earlier.

Further, when the determination result in step S150 is YES, as shown in FIG. 9, the first control valve V1 is put into a half-open state (for example, a 1/4 open state lower than the opening degree in step S151). At the same time as controlling, the second control valve V2 and the third control valve V3 are controlled to the fully open state (step S160), and the process is terminated. When the temperature of the hydraulic oil exceeds a predetermined temperature, oxidation is accelerated and the performance deteriorates. 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 the predetermined reference temperature T3 (for example, 60 ° C.), the second control valve V2 Is controlled to be in a fully closed state to block the inflow of cooling water to the hydraulic oil heat exchanger 50, so that it is possible to prevent the temperature of the hydraulic oil from rising too high.

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

As shown in FIGS. 12 and 13, the opening degree 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 opening degree of the third control valve V3 in this way, heat dissipation from the cooling water by the radiator 17 is suppressed to suppress a decrease in the temperature of the cooling water, and the cooling water to the radiator 17 is suppressed only by the thermostat valve 20. Since the cooling water having a higher temperature than that in the case of controlling the flow rate can be flowed to the hydraulic oil heat exchanger 50, the exchange heat capacity can be maximized and the hydraulic oil can be heated at an early stage.

The temperature characteristic of the opening degree 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, and the flow rate of the cooling water to the radiator 17 by the thermostat valve 20 alone is determined. In the case of controlling, it is controlled to adjust the temperature of the cooling water with an emphasis on fuel efficiency, 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 rise of the hydraulic oil is not sufficient, the cooling water is dissipated by the radiator 17. This leads to a decrease in efficiency from the viewpoint of raising the temperature of the hydraulic oil. Therefore, in the present embodiment, the third control valve V3 is configured to have a larger opening at a higher temperature than the thermostat valve 20, and the decrease in the temperature of the cooling water is suppressed to cool the third control valve at a higher temperature. It was configured to allow water to flow through the hydraulic oil heat exchanger 50. However, the temperature characteristic of the opening degree of the third control valve V3 with respect to the temperature characteristic of the opening degree of the thermostat valve 20 is within a range in which the fuel consumption does not decrease due to the increase in the temperature of the cooling water (that is, the increase in the temperature of the engine 100). Alternatively, the improvement in work efficiency due to the improvement in operability of the work machine due to the early temperature rise of the hydraulic oil is set in a range that exceeds the decrease in efficiency due to a slight decrease in fuel consumption.

The reference temperature T4 at which the third control valve V3 starts to change from the fully closed state to the half open state is an appropriate temperature (for example, 95 ° C.) equal to or lower than the alarm temperature (for example, 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 temperature of the cooling water rises earlier than the hydraulic oil temperature. At this time, the third control valve V3 is in the fully closed state. Then, by flowing high-temperature cooling water through the hydraulic oil heat exchanger 50, when the temperature of the hydraulic oil rises and reaches a predetermined temperature (reference temperature T3), the third control valve V3 is controlled to be fully open. The high temperature cooling water is passed through the radiator 17. As a result, the temperature of the cooling water can be lowered and the engine 100 can be prevented from overheating.

The effect of the present embodiment configured as described above will be described.

In the prior art, there is one related to automobiles in which the overall energy efficiency is improved 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 conditions for use in automobiles, it is suitable for early temperature rise of the hydraulic oil when a large amount of hydraulic oil is used such as a work machine. There was room for improvement in energy efficiency when applied to work machines rather than technology.

On the other hand, in the present embodiment, the engine 100, the hydraulic pump 101 driven by the engine 100, and the hydraulic actuators (boom cylinder 12, arm cylinder 14) driven by the hydraulic oil discharged from the hydraulic pump 101. , Bucket cylinder 16), hydraulic oil tank 102 for storing hydraulic oil, radiator 17 for cooling the cooling water for cooling the engine 100, and heater core 40 for heating the air sent to the cab 9 by the heat of the cooling water. , An outside 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 by the heat of the exhaust gas of the engine 100. A first circulation circuit C1 that allows the cooling water that flows 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 hydraulic oil heat exchanger 50 that causes the cooling water that flows out of the engine 100 to flow into the engine 100. A second circulation circuit C2 that flows into the engine via the exhaust heat recovery device 60, a third circulation circuit C3 that causes the cooling water that has flowed out of the engine 100 to flow into the engine 100 via the radiator 17, and the engine 100. 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 that adjusts the flow rate of the cooling water flowing into the heat exchanger 50, and a third control valve V3 that adjusts the flow rate of the 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 degree 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. The ECU 300 includes a thermostat valve 20 that controls the flow rate of the cooling water flowing from the radiator 17 to the engine 100 according to the temperature of the cooling water flowing through, and the ECU 300 is a third control valve according to the detection result of the water temperature sensor 71. The temperature of the cooling water when the ECU 300 controls the third control valve V3 from the closed state to the open state when the opening degree of the V3 is controlled and the detection result of the outside temperature sensor 70 is equal to or lower than the predetermined reference temperature. Since the temperature of the thermostat valve 20 is set to be higher than the temperature when the thermostat valve 20 is opened from the closed state, the energy efficiency can be improved and the temperature of the hydraulic oil can be raised at an early stage.

That is, according to the present embodiment, the hot water circulation circuit is appropriately switched by using the cooling water whose water temperature is raised by the heat recovered from the exhaust gas of the engine by the exhaust heat recovery device according to the operating condition of the construction machine. It is possible to raise the temperature of the hydraulic oil for the hydraulic pump at an early stage while maintaining the heating performance in the cab. Therefore, the energy efficiency of the entire work machine including fuel consumption can be improved.

Further, since the hydraulic oil is configured to be heated by the thermal energy of the cooling water, the hydraulic oil can be heated at an early stage, 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 considered to be lower, heat dissipation from the cooling water by the radiator 17 is suppressed to suppress a decrease in the temperature of the cooling water, so that the operation is more efficient. The temperature of the oil can be raised at an early stage.

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

FIG. 10 is a diagram showing a state of switching the open / closed state of the first to third control valves according to the present modification.

In the second circulation circuit C2, 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, when the hydraulic oil temperature rises and reaches a predetermined temperature T5 (for example, 25 ° C.), the operation of the operation device is operated from the detection result of the operation amount sensor 74. When the state is determined and the operating state is half lever or less, the second control valve V2 is controlled to the fully open state and the third control valve V3 is controlled to the fully closed state. If the operating state of the operating device is a full lever, the second control valve V2 is controlled to the fully closed state and the third control valve V3 is controlled to the fully open state. By this control, it is possible to prevent the hydraulic oil from rising excessively by applying each throttle energy on the hydraulic system by the full lever operation. Further, it is possible to prevent the cooling water from suddenly rising due to the sudden increase in the engine load due to the full lever operation, and it is possible to prevent the engine 100 from overheating.

Next, the 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 actuator driven by the hydraulic oil discharged from the hydraulic pump (for example, boom cylinder 12, arm cylinder 14). , Bucket cylinder 16), hydraulic oil tank 102 for storing the hydraulic oil, radiator 17 for cooling the cooling water for cooling the engine, and air sent to the cab (for example, cab 9) for the cooling water. The heater core 40 that heats by heat, the outside temperature sensor 70 that detects the outside air temperature, the 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. From the exhaust heat recovery device 60 that heats the cooling water, the first circulation circuit C1 that causes the cooling water that has flowed out from the engine to flow into the engine via the heater core and the exhaust heat recovery device, and the engine. A second circulation circuit C2 that causes the outflowed cooling water to flow into the engine via the hydraulic oil heat exchanger and the exhaust heat recovery device, and the cooling water that has flowed out of the engine via the radiator. A third circulation circuit C3 to flow into the engine, a water temperature sensor 71 to detect the temperature of the cooling water in the engine, and a second to adjust the flow rate of the cooling water flowing into the heater core in the first circulation circuit. The control valve V1 of 1, the 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 the opening of the first and second control valves. A control device (for example, ECU 300) that controls each degree to adjust the flow rate of the cooling water, and the temperature of the cooling water that is provided between the radiator and the engine of the third circulation circuit and flows through the cooling water. In a work machine provided with a thermostat valve 20 for controlling the flow rate of the cooling water flowing from the radiator into the engine according to the above, the radiator in the third circulation circuit flows into the engine via the thermostat. A third control valve V3 for adjusting the flow rate of the cooling water is provided, and the control device closes the third control valve when the detection result of the outside temperature sensor is equal to or lower than a predetermined reference temperature. According to the detection result of the water temperature sensor, the temperature 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 opened from the closed state. The opening degree of the control valve is controlled.

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

(2) Further, in the above-described embodiment, in the work machine of (1), when the detection result of the water temperature sensor 71 is equal to or lower than the predetermined switching temperature, the control device (for example, ECU 300) is described. When the second control valve V2 is controlled to the closed state while controlling the first control valve V1 to the open state and the detection result of the water temperature sensor is higher than the switching temperature, the first control valve The second control valve was controlled to the open state while controlling the closed state.

(3) Further, in the above embodiment, in the work machine of (2), the oil temperature sensor 73 for detecting the temperature of the hydraulic oil stored in the hydraulic oil tank 102 is provided, and the control device (for example, The ECU 300) controls the second control valve V2 to be in a half-open state when the detection result of the oil temperature sensor is equal to or lower than a predetermined temperature.

(4) Further, in the above-described embodiment, in the work machine of (2), the control device (for example, ECU 300) operates the hydraulic actuator (for example, boom cylinder 12, arm cylinder 14, bucket cylinder 16). The opening degree of the second control valve V2 is controlled according to the detection result of the operation amount sensor 74 that detects the operation amount of the operation device for the operation.

<Additional notes>
The present invention is not limited to the above-described embodiment, and includes various modifications and combinations within a range that does not deviate from the gist thereof. Further, the present invention is not limited to the one including all the configurations described in the above-described embodiment, and includes the one in which a part of the configurations is deleted. Further, each of the above configurations, functions and the like may be realized by designing a part or all of them by, for example, an integrated circuit. Further, each of the above configurations, functions, and the like may be realized by software by the processor interpreting and executing a program that realizes each function.

1 ... Lower traveling body, 2 ... Upper rotating body, 3 ... Front device, 4 ... Crawler frame, 5 ... Crawler, 7 ... Travel motor, 8 ... Swivel 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 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 temperature comparison unit, 300b ... water temperature comparison unit, 300c ... room temperature comparison unit, 300d ... oil temperature comparison unit, 300e ... operation amount comparison unit, 300f ... control unit, C1 ... first circulation circuit, C2 ... 2nd circulation circuit, C3 ... 3rd circulation circuit, H1 ... H11 ... Pipe line, V1 ... 1st control valve, V2 ... 2nd control valve, V3 ... 3rd control valve

Claims (4)

With the engine
The hydraulic pump driven by the engine and
A hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump and
A hydraulic oil tank for storing the hydraulic oil and
A radiator that cools the cooling water that cools the engine, and
A heater core that heats the air sent to the driver's cab with 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 flowing out of the engine to flow into the engine via the heater core and the exhaust heat recovery device.
A second circulation circuit that causes the cooling water flowing 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 allows 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, and
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 second control valve for adjusting the flow rate of the cooling water flowing into the hydraulic oil heat exchanger in the second circulation circuit, and
A control device that controls the opening degree of the first and second control valves to adjust the flow rate of the cooling water, and
A thermostat valve provided between the radiator and the engine of the third circulation circuit and controlling the flow rate of the cooling water flowing from the radiator into the engine according to the temperature of the cooling water flowing through the engine. In the equipped work machine
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 via the thermostat valve is provided.
In the control device, when the detection result of the outside air temperature sensor is equal to or lower than a predetermined reference temperature, the temperature at which the third control valve is controlled from the closed state to the open state is higher than the temperature at which the thermostat valve is closed. A work machine characterized in that the opening degree of the third control valve is controlled according to the detection result of the water temperature sensor so that the temperature becomes higher than the temperature of the cooling water when the state is changed to the open state. In the work machine according to claim 1,
When the detection result of the water temperature sensor is equal to or lower than the predetermined switching temperature, the control device controls the second control valve to the closed state while controlling the first control valve to the open state. A work machine characterized in that when the detection result of the water temperature sensor is higher than the switching temperature, the first control valve is controlled to the closed state and the second control valve is controlled to the open state. In the work machine according to claim 2.
The oil temperature sensor for detecting the temperature of the hydraulic oil stored in the hydraulic oil tank is provided.
The control device is a work machine characterized in that when the detection result of the oil temperature sensor is equal to or lower than a predetermined temperature, the second control valve is controlled to a half-open state. In the work machine according to claim 2.
The control device is a work machine characterized in that the opening degree of the second control valve is controlled according to the detection result of the operation amount sensor that detects the operation amount of the operation device for operating the hydraulic actuator.

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