JP6511953B2 - Engine cooling system and engine cooling method - Google Patents

Description

  The present invention relates to a cooling system for an engine and a method for cooling an engine, and more specifically, cools both an engine body and intake air supercharged by a supercharger to avoid fuel consumption deterioration while avoiding deterioration of exhaust gas performance. The present invention relates to an engine cooling device and an engine cooling method for suppressing the thickness increase of the device without increasing the number of radiators.

  As a cooling device for an engine, one provided with a water-cooled heat exchanger for cooling intake air supercharged by a supercharger with cooling water in addition to an engine body has been proposed (see, for example, Patent Document 1) ).

  However, if the temperature of the cooling water supplied to the water-cooled heat exchanger at low engine speed or low load is higher than the temperature of the intake air at the outlet of the turbocharger, the intake air can not be cooled but it is There is a problem that the temperature rises and the exhaust gas performance is deteriorated because the required intake volume at the time of combustion can not be secured, and if the supercharging pressure is increased to secure the necessary intake volume, the fuel efficiency is increased There was a problem of getting worse.

  Therefore, the above-described apparatus is not limited to the engine radiator for cooling the cooling water supplied to the engine main body, and the intercooler radiator for cooling the cooling water supplied to the water-cooled heat exchanger. Equipped with two radiators, and if the temperature of the cooling water supplied to the water-cooled heat exchanger is higher than the temperature of the intake air at the outlet of the turbocharger, adjusting the water volume of the intercooler cooling radiator The fuel efficiency is improved while suppressing the deterioration of the gas performance.

  However, providing the two radiators of the engine radiator and the intercooler cooling radiator causes the apparatus to become thicker and thicker, resulting in a new problem that fuel consumption is deteriorated.

Japanese Utility Model Publication No. 6-25637

  The object of the present invention is to improve the fuel consumption while cooling both the engine body and the intake air supercharged by the supercharger to avoid the deterioration of the exhaust gas performance, and to increase the weight of the device without increasing the number of radiators. An engine cooling device and an engine cooling method capable of suppressing an increase in size.

  An engine cooling device according to the present invention for achieving the above object comprises: a mechanical water pump; an engine body; a radiator; and a bypass passage bypassing the radiator, and the mechanical water pump in this order. An engine cooling device comprising: a main cooling circuit that circulates; and an auxiliary cooling circuit that circulates cooling water to a water-cooled heat exchanger that cools intake air supercharged by a turbocharger; A first cooling circuit in which cooling water circulates in the order of the mechanical water pump, the water cooling heat exchanger, and the mechanical water pump, and the cooling water is an electric water pump, the water cooling heat exchanger, the water cooling heat exchanger A radiator, a second cooling circuit circulating in the order of the electric water pump, and a flow path of cooling water flowing to the water-cooled heat exchanger are provided at the outlet of the mechanical water pump. Switching to the first cooling circuit and stopping the electric water pump when the outlet temperature of the cooling water is lower than the intake temperature of the intake at the outlet of the supercharger, while the outlet temperature is higher than the intake temperature In this case, a cooling circuit switching mechanism for switching the second cooling circuit and driving the electric water pump is provided.

  Further, according to the engine cooling method of the present invention which achieves the above object, any one of a mechanical water pump, an engine body, a radiator and a bypass passage bypassing the radiator, and the mechanical water pump In order to cool the engine body by circulating it in the following order, cooling water is circulated to a water-cooled heat exchanger that cools the intake air supercharged by the turbocharger to cool the water-cooled heat exchanger In the method, when the outlet temperature of the cooling water at the outlet of the mechanical water pump is lower than the intake temperature of the intake air at the outlet of the turbocharger, the mechanical water pump, the water cooled heat exchanger, And circulating the mechanical water pump in order to cool the water-cooled heat exchanger, and driving the electric water pump when the outlet temperature is higher than the intake temperature. The cooling water, the electric water pump, the water-cooling heat exchanger is the radiator, and a method which is characterized in that circulates in the order of the electric water pump for cooling the water-cooled heat exchanger.

  According to the engine cooling device and engine cooling method of the present invention, when the outlet temperature of the cooling water at the outlet of the mechanical water pump is lower than the intake temperature of the intake air at the outlet of the turbocharger, the radiator of the main cooling circuit The cooling water is supplied to the water-cooled heat exchanger in a first cooling circuit that does not intervene, and when the outlet temperature is equal to or higher than the intake temperature, the electric water pump is driven to drive the second cooling radiator via the main cooling circuit. Since the cooling water is supplied to the water-cooled heat exchanger in the cooling circuit, the second cooling circuit can also be used for the radiator even in the low rotation and low load region of the engine where the outlet temperature of the cooling water is higher than the intake temperature. Cooling water that is cooled to a temperature below the intake air temperature can be supplied to the water-cooled heat exchanger, and the water-cooled heat exchanger can cool the supercharged intake air with the supercharger. As a result, the amount of intake air can be increased without increasing the work of the supercharger in the low rotation speed or low load area of the engine, thereby improving the fuel efficiency while suppressing the deterioration of the exhaust gas performance. can do.

  In addition, since one radiator is shared by the main cooling circuit and the sub-cooling circuit, it is possible to suppress the increase in thickness of the apparatus without increasing the number of radiators for cooling the intake air in a water-cooled heat exchanger. it can. As a result, space saving of the engine room can be achieved and fuel consumption can be further improved.

  In addition, when the outlet temperature of the cooling water is equal to or higher than the intake air temperature, the electric water pump is driven to supply the cooling water cooled by the radiator to the water-cooled heat exchanger. The flow rate of the cooling water supplied to the water-cooled heat exchanger can also be adjusted, and the intake air can be reliably cooled even when the discharge rate of the mechanical water pump is small at low engine speed and low load. .

It is a block diagram which illustrates the cooling device for engines of 1st embodiment of this invention, and shows the case where the exit temperature of the cooling water in the exit of a water pump is less than the intake temperature of the intake air in the exit of a supercharger. It is a block diagram which illustrates the cooling device for engines of a first embodiment of the present invention, and shows the case where the outlet temperature of cooling water is more than intake temperature. It is map data which illustrates the relationship between the fuel injection quantity of the engine main body of FIG. 1, the exit temperature of a cooling water, intake-air temperature, and the inlet temperature of the cooling water in the inlet of a water-cooled heat exchanger. It is a block diagram which illustrates the 1st modification of the cooling device for engines shown in FIG.1 and FIG.2. It is a block diagram which illustrates the 2nd modification of the cooling device for engines shown in FIG.1 and FIG.2. It is a block diagram which illustrates the cooling device for engines of 2nd embodiment of this invention, and shows warming up of an engine main body. It is a block diagram which illustrates the cooling device for engines of 2nd embodiment of this invention, and shows the case where the exit temperature of the cooling water of the outlet of a water pump is less than the intake temperature of the inhalation | air-intake in the exit of a turbocharger. It is a block diagram which illustrates the cooling device for engines of 2nd embodiment of this invention, and shows the case where the exit temperature of the cooling water of the outlet of a water pump is less than the intake temperature of the inhalation | air-intake in the exit of a turbocharger. It is a block diagram which illustrates the cooling device for engines of 2nd embodiment of this invention, and shows the case where the exit temperature of a cooling water is more than intake temperature. It is a flow figure which illustrates the cooling method of the engine of an embodiment of the present invention. It is the map data which illustrates the 1st field and the 2nd field which were set up based on engine number of rotations and output torque of an engine body of Drawing 6A. It is a block diagram which illustrates the 1st modification of the cooling device for engines shown in FIGS. 6-9. It is a block diagram which illustrates the 2nd modification of the cooling device for engines shown in FIGS. 6-9.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 illustrate an engine cooling device 30 according to a first embodiment of the present invention. Note that the alternate long and short dash line in the figure indicates a control signal.

  The engine cooling device 30 cools the engine 10 mounted on a vehicle. In the engine 10, the intake air A drawn into the intake passage 11 when the vehicle is traveling is compressed by the compressor (supercharger) 13 of the turbocharger 12 to a high temperature, and the water-cooled intercooler (water-cooled thermal) After being cooled by the exchanger (14), it is supplied to the engine body 16 through the intake manifold 15. The intake air A supplied to the engine main body 16 is mixed with the fuel injected into the cylinder 17 and burned to generate thermal energy, and then becomes exhaust gas G and is exhausted from the exhaust manifold 18 to the exhaust passage 19 After the turbine 20 of the turbocharger 12 is driven, the gas is purified by an exhaust gas purification device (not shown) and then released to the atmosphere. The control device 21 controls the fuel injection amount of the engine 10 and the like.

  The engine cooling device 30 includes a main cooling circuit 31 for cooling the engine body 16 and a sub cooling circuit 40 for cooling the water-cooled intercooler 14. In the main cooling circuit 31, the cooling water W includes a first cooling passage 35 in which the water pump 32, the engine body 16, the thermostat 33, and the radiator 34 are interposed halfway and a bypass passage 36 bypassing the radiator 34. One or the other and the water pump 32 circulate in this order.

  The water pump 32 is a mechanical type, and the rotational power of the engine body 16 is transmitted from the crankshaft 22 through a power transmission mechanism 23 such as an endless belt or gear mechanism, and is driven by this rotational power.

The thermostat 33 is disposed on the outlet side of the engine main body 16 of the main cooling circuit 31. The thermostat 33 includes a lifter (not shown) that expands and contracts with a thermal expansion body having a property of expanding as the temperature rises and shrinking as the temperature decreases, and the cooling water W heated by the engine main body 16 The flow rate of the cooling water W flowing through the first cooling passage 35 and the bypass passage 36 is adjusted by the expansion and contraction of the lifter according to the temperature. In addition, you may use for this thermostat 33 the electrothermal thermostat which carries out expansion-contraction operation of lift forcibly by electrical heat.

  As described above, the thermostat 33 is disposed on the outlet side of the engine main body 16 of the main cooling circuit 31 and the water temperature of the cooling water W is controlled on the outlet side. This can improve and suppress the occurrence of cavitation, which is advantageous for improving the durability, and is particularly suitable for a large vehicle such as a truck.

  The radiator 34 is disposed on the front side of the vehicle on which the engine 10 and the engine cooling device 30 are mounted, and a cooling fan 37 coupled to the crankshaft 22 and driven behind the radiator 34 is disposed. The radiator 34 cools the cooling water W passing inside by using the vehicle speed wind and the cooling air by the subsequent cooling fan 37.

  In such an engine cooling device 30, the sub cooling circuit 40 is configured to include a first cooling circuit 41, a second cooling circuit 43 having an electric water pump 42, and a cooling circuit switching mechanism. As shown in FIG. 1, the first cooling circuit 41 is a circuit in which the cooling water W1 circulates in the order of the water pump 32, the water-cooled intercooler 14, and the water pump 32, and the second cooling circuit 43 is a circuit. As shown in 2, the cooling water W2 is a circuit in which the electric water pump 42, the water-cooled intercooler 14, the radiator 34, and the electric water pump 42 circulate in this order. The cooling circuit switching mechanism is a mechanism for switching the first cooling circuit 41 and the second cooling circuit 43.

  The cooling circuit switching mechanism stops the electric water pump 42 and the sub cooling circuit when the outlet temperature Tout of the cooling water W at the outlet of the water pump 32 is less than the intake temperature Ta of the intake air A at the outlet of the compressor 13. The flow path of 40 is switched to the first cooling circuit 41, and when the outlet temperature Tout is equal to or higher than the intake air temperature Ta, the electric water pump 42 is driven and the flow path of the sub cooling circuit 40 is switched to the second cooling circuit 43. Configured

  The cooling circuit switching mechanism is not particularly limited as long as the flow path of the sub cooling circuit 40 can be switched to either the first cooling circuit 41 or the second cooling circuit 43, but the first cooling circuit is not particularly limited. 41, a first valve 44 interposed between the water pump 32 and the water-cooled intercooler 14, a second valve 45 interposed between the water-cooled intercooler 14 and the water pump 32, electric water It is desirable that the controller 21 be configured to control the drive of the pump 42 and to adjust the opening degree of the first valve 44 and the second valve 45, respectively.

  The first cooling circuit 41 is a circuit that does not include the radiator 34, and includes a first introduction passage 46 connecting the outlet of the water pump 32 and the inlet of the water cooled intercooler 14, the outlet of the water cooled intercooler 14, and the water pump And a first outlet passage 47 connecting the 32 inlets. The first introduction passage 46 may be directly connected to the outlet of the water pump 32, and the first lead-out passage 47 may also be directly connected to the inlet of the water pump 32.

  The first cooling circuit 41 is a circuit corresponding to the flow rate when the engine body 16 is in a high load and high rotation operation state, that is, when the discharge flow rate of the water pump 32 is maximum. The temperature of the cooling water W1 circulating through the first cooling circuit 41 is the same as the outlet temperature Tout of the cooling water W at the outlet of the water pump 32.

  The electric water pump 42 is connected to the electric motor 28, and is driven by the control device 21 driving the electric motor 28 and stopped by stopping the driving of the electric motor 28. The electric motor 28 is connected to a battery (not shown).

  The second cooling circuit 43 is a circuit for passing the cooling water W2 to the radiator 34 by the electric water pump 42. The second cooling circuit 43 connects the outlet of the radiator 34 and the inlet of the water-cooled intercooler 14 and It comprises a second cooling passage 48 in which a pump 42 is interposed and a second lead-out passage 49 connecting the outlet of the water-cooled intercooler 14 and the inlet of the radiator 34. The second cooling passage 48 may be directly connected to the inlet of the water-cooled intercooler 14, and the second lead-out passage 49 may also be directly connected to the outlet of the water-cooled intercooler 14.

  Further, in the second cooling circuit 43, the cooling water W circulating in the main cooling circuit 31 mainly flows through the bypass passage by the thermostat 33 when the engine main body 16 is in the low load and low rotation operating condition. It is a circuit that is switched when, and is a circuit for low flow rate compared to the first cooling circuit 41. The temperature of the cooling water W 2 circulated through the second cooling circuit 43 and passed through the radiator 34 by the electric water pump 42 is lower than the outlet temperature Tout of the cooling water W at the outlet of the water pump 32.

  The first valve 44 is interposed in the first introduction passage 46, and is opened and closed by the control signal (current value) sent from the control device 21 to open and shut the first introduction passage 46, opening and closing It is comprised by the flow control valve which can adjust the flow volume of the cooling water W1 which flows through the 1st introductory passage 46 repeatedly, or the flow control valve whose opening degree is adjusted, such as a rotary valve and a proportional control valve, and is adjustable.

  The second valve 45 is interposed in the first lead-out passage 47, and is opened / closed to open / close the first lead-out passage 47 by the control signal (current value) sent from the control device 21. It is comprised by the flow control valve which can adjust the flow volume of the cooling water W2 which flows through the 1st derivation | leading-out path | pass 47 repeatedly, or the flow control valve whose opening degree is adjusted, such as a rotary valve and a proportional control valve.

  The control device 21 is connected to a first water temperature sensor 50 that detects the outlet temperature Tout of the cooling water W at the outlet of the water pump 32, and an intake temperature sensor 51 that detects the intake temperature Ta of the intake air A at the outlet of the compressor 13. It is done.

  The first water temperature sensor 50 is preferably disposed between the outlet of the water pump 32 and the inlet of the engine body 16, and is disposed between the outlet of the water pump 32 and the branch of the first introduction passage 46. Is more preferred. The intake air temperature sensor 51 is preferably disposed between the outlet of the compressor 13 and the inlet of the intake air A of the water-cooled intercooler 14. Note that, instead of the first water temperature sensor 50, a means for estimating the outlet temperature Tout of the cooling water W at the outlet of the water pump 32 based on the water temperature detected by the second water temperature sensor disposed at the outlet of the engine main body 16 May be

  3 shows the fuel injection amount Qe injected into the cylinder 17, the outlet temperature Tout of the cooling water W at the outlet of the water pump 32, the intake temperature Ta of the intake air A at the outlet of the compressor 13, and the inlet of the water cooled intercooler 14. The relationship of the inlet temperature Tin of the cooling water W1 in W2 and W2 is illustrated. The straight line indicates the outlet temperature Tout, the dashed-dotted line indicates the intake air temperature Ta, and the dotted line indicates the inlet temperature Tin.

  The outlet temperature Tout is determined by the cooling water W after cooling the engine body 16 being distributed to each of the first cooling passage 35 and the bypass passage 36 or to either of them by the thermostat 33 according to the temperature. It is adjusted to be the set temperature T1 within the range. The temperature T1 is preset according to the specifications of the engine 10, and is set to, for example, 65 ° C. or more and 105 ° C. or less.

  On the other hand, the intake air temperature Ta increases in proportion to the fuel injection amount Qe, and becomes equal to the set temperature T1 at a predetermined fuel injection amount Q1. Therefore, the intake air temperature Ta has an area lower than the set temperature T1 and an area which is higher than the set temperature T1.

  Therefore, in the engine cooling device 30, the electric water pump 42 is driven by the cooling circuit switching device and the flow path of the sub cooling circuit 40 is used in the region where the intake air temperature Ta is lower than the outlet temperature Tout, that is, the set temperature T1. Switching to the second cooling circuit 43 is performed. As a result, the cooling water W2 is cooled by the radiator 34 so that the inlet temperature Tin is lower than the intake air temperature Ta, and the cooling water W2 having a temperature lower than the intake air temperature Ta is supplied to the water-cooled intercooler 14 Thus, the intake air A supercharged by the compressor 13 can be cooled.

  On the other hand, in the region where the intake air temperature Ta is equal to or higher than the outlet temperature Tout, the electric water pump 42 is stopped by the cooling circuit switching device and the flow path of the sub cooling circuit 40 is switched to the first cooling circuit 41. Thereby, when the cooling water W is cooled by the radiator 34 in the main cooling circuit 31 by the thermostat 33, the first cooling circuit 41 of the sub cooling circuit 40 supercharges the compressor 13 without using the radiator 34. The intake air A can be cooled.

  As described above, since the flow path of the sub cooling circuit 40 is switched by the cooling circuit switching device, the second cooling circuit 43 is also performed in the low rotation speed and low load region of the engine 10 where the outlet temperature Tout becomes higher than the intake temperature Ta. The cooling water W2 cooled by the radiator 34 so that the temperature T becomes lower than the intake air temperature Ta is supplied to the water-cooled intercooler 14 to cool the intake air A supercharged by the compressor 13 by the water-cooled intercooler 14 Can. As a result, the boost pressure can be increased without increasing the work of the compressor 13 in the low rotation speed or low load region of the engine 10, and therefore, the fuel efficiency is improved while suppressing the deterioration of the exhaust gas performance. be able to.

  Further, since one radiator 34 is shared by the main cooling circuit 31 and the sub-cooling circuit 40, the cooling device 30 of the engine cooling device 30 can be used without increasing the number of radiators for cooling the water-cooled intercooler 14. It is possible to suppress the increase in thickness. As a result, space saving of the engine room can be achieved and fuel consumption can be further improved.

  In addition, when the outlet temperature Tout is equal to or higher than the intake air temperature Ta, the electric water pump 42 is driven to supply the cooling water W2 cooled by the radiator 34 to the water-cooled intercooler 14. The flow rate of the cooling water W2 supplied to the water-cooled intercooler 14 can also be adjusted by the pump 42, and even when the discharge flow rate of the mechanical water pump 32 is small when the engine 10 has low rotation or low load, The intake air A can be cooled.

  In the above embodiment, the detection values of the first water temperature sensor 50 and the intake air temperature sensor 51 are compared, and the flow path of the sub cooling circuit 40 is switched. However, instead of one of the detection values, Alternatively, the control device 21 may store a preset target temperature and compare the target temperature with the other detection value to switch the flow path.

  In the first embodiment, the engine cooling device 30 for outlet control in which the thermostat 33 is disposed on the outlet side of the engine main body 16 of the main cooling circuit 31 has been described, but as shown in FIG. The present invention can also be applied to an inlet-controlled engine cooling device 30 in which a thermostat 33 is disposed on the inlet side of the main body 16. In the case of inlet control, it is advantageous in terms of temperature control of the cooling water W as compared with outlet control.

  In the first embodiment, the first lead-out passage 47 is connected between the radiator 34 and the water pump 32. However, as shown in FIG. 5, the first lead-out passage 47 is the outlet from the engine main body 16 And the thermostat 33 may be connected.

  6 to 9 illustrate an engine cooling device 30 according to a second embodiment of the present invention.

  In the engine cooling device 30 according to the second embodiment, as shown in FIG. 6, the electric water pump 42 is stopped by the cooling circuit switching mechanism and the flow path of the sub cooling circuit 40 is maintained while the engine body 16 is warming up. The first cooling circuit 41 is configured to be switched.

  In addition to the configuration of the first embodiment, a third valve 52 is interposed between the radiator 34 of the second cooling circuit 43 and the electric water pump 42, and the control device 21 drives the electric water pump 42. When the electric water pump 42 is stopped, control is performed to bring the third valve 52 to the opening side. Ru.

  Furthermore, in addition to the configuration of the first embodiment, the fourth valve 53 is interposed between the radiator 34 of the main cooling circuit 31 and the water pump 32, and the control device 21 controls the cooling water flowing to the radiator 34 by the thermostat 33. Control is performed to adjust the opening degree of the fourth valve 53 in accordance with the flow rate of W. Specifically, when the flow rate of the first cooling passage 35 in which the radiator 34 is interposed is increased by the thermostat 33, the fourth valve 53 is controlled to have an opening degree on the open side, while the first cooling is performed. When the flow rate of the passage 35 decreases, the fourth valve 53 is controlled to open at the closing side.

  The third valve 52 is opened and closed by the control signal (current value) sent from the control device 21 to open and shut off the radiator 34 and the electric water pump 42, and the opening and closing are repeated to output electric water from the radiator 34 A flow control valve capable of adjusting the flow rate of the cooling water W flowing to the pump 42 or a flow control valve capable of adjusting the flow rate by adjusting the opening degree of a rotary valve, a proportional control valve or the like is configured.

  The fourth valve 53 is opened and closed by the control signal (current value) sent from the control device 21 to open and shut off the radiator 34 and the water pump 32, and the opening and closing are repeated so that the radiator 34 to the water pump 32. A flow control valve capable of adjusting the flow rate of the cooling water W flowing to the valve, or a flow control valve capable of adjusting the flow rate by adjusting the opening degree of a rotary valve, a proportional control valve or the like.

  A method of cooling the engine 10 equipped with the engine cooling device 30 will be described below as a function of the control device 21 based on the flowcharts shown in FIGS. The control of this flowchart is started when the engine body 16 starts up, that is, when the water pump 32 starts driving.

  First, in step S10, the controller 21 determines whether the engine body 16 is warming up. Specifically, the engine body 16 is warmed up by the temperature of the cooling water W after the engine body 16 is cooled after the engine body 16 is started by the start key, that is, the engine temperature detected by the second water temperature sensor 54 This is until Te reaches a predetermined temperature set to, for example, 60 ° C. or more and 80 ° C. or less. The determination as to whether the engine main body 16 is being warmed up is not limited to the determination based on the engine temperature Te, but may be based on, for example, the temperature of the engine oil. In this step S10, if the engine body 16 is warming up, the process proceeds to step S20, and if the engine body 16 is not warming up, the process proceeds to step S30.

  Next, in step S20, as shown in FIG. 6, the controller 21 opens the first valve 44 and the second valve 45 to the open side, and closes the third valve 52 and the fourth valve 53 to the close side. At this time, the first valve 44 and the second valve 45 may be fully open, and the third valve 52 and the fourth valve 53 may be fully closed.

  Next, in step S30, the control device 21 determines whether the outlet temperature Tout detected by the first water temperature sensor 50 is equal to or higher than the intake air temperature Ta detected by the intake air temperature sensor 51. In step S30, when the outlet temperature Tout is equal to or higher than the intake air temperature Ta, the process proceeds to step S40. On the other hand, when the outlet temperature Tout is lower than the intake air temperature Ta, the process proceeds to step S60.

  Next, in step S40, as shown in FIG. 8, the controller 21 drives the electric water pump 42. Next, in step S50, the controller 21 opens the first valve 44 and the second valve 45 to the closing side, opens the third valve 52 to the opening side, and closes the fourth valve 53 to the closing side. At this time, it is preferable that the first valve 44 and the second valve 45 be fully closed so that the cooling water W1 does not flow through the first cooling circuit 41. Further, the third valve 52 can maintain the outlet temperature Tout at the set temperature T1, and an opening degree proportional to the operating state of the engine 10, that is, the inlet temperature Tin after passing through the radiator 34 becomes less than the intake temperature Ta. When the operating condition of the engine 10 is low rotation and low load, the opening degree is controlled to be smaller, and when the operating condition of the engine 10 is high rotation and high load, the opening degree is controlled to be larger. Is preferred. In addition, it is preferable that the fourth valve 53 be controlled to an opening on the closed side proportional to the flow rate of the cooling water W flowing to the first cooling passage 35 by the thermostat 33.

  By performing steps S40 and S50, the cooling water W2 which has been cooled to a temperature lower than the intake air temperature Ta by the electric water pump 42 through the radiator 34 is supplied to the water-cooled intercooler 14 to cool the intake air A. Do.

  Further, when the operating state of the engine 10 approaches the high speed and high load in the steps S40 and S50, the fuel injection amount Qe increases, and as shown in FIG. The flow rate of the cooling water W flowing to 35 is increased. Thus, when the flow rate of the cooling water W flowing into the first cooling passage 35 increases, the intake air temperature Ta approaches the outlet temperature Tout, and the outlet temperature Tout approaches the inlet temperature Tin. Then, the outlet temperature Tout, the intake air temperature Ta, and the inlet temperature Tin become equal to each other at a predetermined fuel injection amount Q1.

  On the other hand, in step S60, as shown in FIG. 10, the control device 21 stops the electric water pump 42. Next, in step S70, the controller 21 opens the first valve 44 and the second valve 45 to the open side, closes the third valve 52 to the close side, and opens the fourth valve 53 to the open side. At this time, it is preferable that the first valve 44 and the second valve 45 be fully open. The third valve 52 is preferably fully closed so that the cooling water W2 does not flow to the second cooling circuit 43. In addition, it is preferable that the fourth valve 53 be controlled to an opening degree on the open side proportional to the flow rate of the cooling water W flowing to the first cooling passage 35 by the thermostat 33.

  By performing steps S60 and S70, in the main cooling circuit 31, the cooling water W is circulated by the thermostat 33 via the first cooling passage 35, and in the sub cooling circuit 40, the cooling water W1 is the first cooling circuit. Circulate via 41.

Further, when the operating state of the engine 10 approaches low rotation and low load in these steps S60 and S70, the fuel injection amount Qe decreases, and the flow rate of the cooling water W flowing into the bypass passage 36 by the thermostat 33 accordingly. Thus, when the flow rate of the cooling water W flowing through the bypass passage 36 increases, the outlet temperature Tout approaches the intake temperature Ta and becomes equal to or less than the predetermined fuel injection amount Q1, the outlet temperature Tout becomes the intake temperature Ta. It will be higher than that.

  Next, in step S80, the control device 21 determines whether the engine 10 has stopped. In step S80, the stop of the engine 10 is determined based on the stop of the injection of fuel to the cylinder 17 of the engine body 16, the engine speed, the speed of the water pump 32, and the like. If it is determined in step S80 that the engine 10 is stopped, the process proceeds to step S90. If it is determined that the engine 10 is not stopped, the process returns to step S30.

  Next, in step S90, the controller 21 opens all of the first valve 44, the second valve 45, the third valve 52, and the fourth valve 53 to the open side, returns to the start, and the control according to this flowchart is completed. Do.

  Since such control is performed, both the engine body 16 and the intake air A supercharged by the compressor 13 are cooled to improve the fuel consumption while avoiding the deterioration of the exhaust gas performance while the number of radiators is increased. It is possible to suppress the increase in thickness and thickness of the device without increasing the number.

  In addition, since step S20 is performed during warm-up of the engine 10, in the main cooling circuit 31, the cooling water W is circulated by the thermostat 33 via the bypass passage 36, and in the sub cooling circuit 40, the cooling water W1 Circulates through the first cooling circuit 41. That is, the warming-up can be promoted by warming the cooling water W1 from the intake air A supercharged by the compressor 13 via the water-cooled intercooler 14 using the first cooling circuit 41 during warming-up. It is advantageous to reduce machine time.

  In addition, since the engine 10 is stopped, that is, step S90 is performed when the water pump 32 is stopped, when the water pump 32 is stopped, the first valve 44, the second valve 45, and the third valve 52, By opening all of the fourth valve 53, it is possible to improve the air bleeding performance while the water pump 32 is stopped, and to suppress the occurrence of cavitation when the water pump 32 resumes driving, It is advantageous to the improvement of durability.

  Further, the third valve 52 is interposed between the radiator 34 and the electric water pump 42, and when the electric water pump 42 is stopped, the second cooling passage 38 is shut off by the third valve 52, It is possible to prevent reverse rotation of the electric water pump 42 due to differential pressure or to prevent water leakage when the electric water pump 42 is stopped.

  Moreover, the fourth valve 53 is interposed between the radiator 34 and the water pump 32, and the opening degree of the fourth valve 53 is adjusted in accordance with the flow rate of the cooling water W flowing to the radiator 34 by the thermostat 33. Therefore, when the outlet temperature Tout is equal to or higher than the intake air temperature Ta, the fourth valve 53 can be set to the opening degree on the closing side in step S50. Thereby, when the water cooling intercooler 14 is cooled by the second cooling circuit 43, the cooling water W can be prevented from flowing from the radiator 34 to the water pump 32, and the operating state of the engine 10 is low. When the load is low, the inlet temperature Tin of the cooling water W2 is reliably lowered to a temperature less than the intake air temperature Ta to cool the intake air A while maintaining the outlet temperature Tout of the cooling water W at the set temperature T1. Can.

In the engine cooling device 30 described above, the controller 21 controls the first region R1 where the outlet temperature Tout is lower than the intake air temperature Ta based on the engine speed and the engine output torque, and the outlet temperature Tout becomes higher than the intake air temperature Ta The map data M1 in which the second region R2 is set is provided, and control is performed to compare the operating state of the engine main body 16 with the map data M1. When the operating state of the engine main body 16 is the first region R1, Control is performed to stop the water pump 42 and set the first valve 44 and the second valve 45 to the open side, while driving the electric water pump 42 in the case of the second region R2 It is desirable to be configured to perform control to bring the valve 44 and the second valve to the closing side.

  FIG. 11 illustrates the map data M1. The map data M1 is stored in the control device 21 with the first region R1 and the second region R2 set in advance by experiments and tests. The first region R1 is a region where the operating state of the engine body 16 is a region of high rotation and high load, and the outlet temperature Tout is lower than the intake air temperature Ta. The second region R2 is a region where the operating state of the engine body 16 is a region of low rotation and low load, and the outlet temperature Tout is equal to or higher than the intake temperature Ta.

  Thus, instead of performing control to compare the detection values of the first water temperature sensor 50 and the intake air temperature sensor 51, the number of sensors is reduced by comparing the operating state of the engine main body 16 with the map data M1. Thus, the cost can be reduced, and the responsiveness of switching of the flow path of the sub cooling circuit 40 can be improved.

  In the second embodiment, the fourth valve 53 is interposed between the radiator 34 and the water pump 32 as an example. However, as shown in FIG. A thermostat 55 may be interposed. When the operating temperature zone of the second thermostat 55 is set to a temperature lower than the operating temperature zone of the thermostat 33, when the cooling water W flows to the first cooling passage 35 by the thermostat 33, the cooling water W is the second thermostat It is possible to avoid being blocked at 55.

  Further, as shown in FIG. 13, the engine cooling device 30 according to the first and second embodiments described above is equipped with a multistage supercharging system provided with a second turbocharger 24 in addition to the first turbocharger 12. It can apply also to the engine 10 which carried out.

  In the engine 10, the exhaust gas G sequentially passes through the turbine 25 of the second turbocharger 24 and the turbine 20 of the first turbocharger 12 to drive them. The intake air A is supercharged by the compressor 13 of the first turbocharger 12 and then cooled by the water cooled intercooler 14 and further supercharged by the compressor 26 of the second turbocharger 24. It is cooled by 27.

  In such a multi-stage supercharging system, since the compressors 13, 26 continuously supercharge, it is particularly necessary to improve the cooling performance of the water-cooled intercooler 14 interposed between the compressors 13, 26. is there. Therefore, by applying the above first and second embodiments to such an engine 10, the supercharging pressure can be increased by the multistage charging system, and the exhaust gas is reduced by lowering the intake temperature Ta of the intake air A. Fuel consumption can be improved while avoiding deterioration in performance.

  The engine cooling device 30 according to the first and second embodiments compares the outlet temperature Tout and the intake air temperature Ta, and switches the first cooling circuit 41 and the second cooling circuit 43 by the cooling circuit switching mechanism. Although the configuration is made, the inlet temperature Tin and the intake temperature Ta can be compared and switched. In this case, as shown in FIG. 3, it is preferable that the switching timing be such that the inlet temperature Tin becomes equal to the intake temperature Ta.

The engine cooling device 30 according to the second embodiment has been described by way of example in which the flow path of the sub cooling circuit 40 is switched to the first cooling circuit 41 during warm-up of the engine 10. Depending on the cooling performance of the water-cooled intercooler 14, the warm-up may not be promoted. In such a case, during warm-up of engine 10, control device 21 performs control to fully close all of first valve 44, second valve 45, third valve 52, and fourth valve 53. By configuring, the warm-up of engine 10 can be promoted.

13 Compressor (supercharger)
14 Water-cooled intercooler (water-cooled heat exchanger)
DESCRIPTION OF SYMBOLS 16 engine main body 21 control apparatus 30 engine cooling apparatus 31 main cooling circuit 32 water pump 33 thermostat 34 radiator 36 bypass passage 40 subcooling circuit 41 1st cooling circuit 42 electric water pump 43 2nd cooling circuit 44 1st valve 45 2nd Valve 50 First water temperature sensor 51 Intake air temperature sensor 52 Third valve 53 Fourth valve Ta Intake air temperature Tout Outlet temperature W Cooling water W1 Cooling water W2 Cooling water

Claims (10)

In the supercharger, the cooling water is circulated by the mechanical water pump, the engine body, the radiator, and the bypass passage bypassing the radiator, and the main cooling circuit in which the mechanical water pump is circulated in order, and the cooling water. An engine cooling system comprising a secondary cooling circuit circulating to a water-cooled heat exchanger for cooling the supercharged intake air;
A first cooling circuit in which cooling water is circulated in the secondary cooling circuit in the order of the mechanical water pump, the water-cooled heat exchanger, and the mechanical water pump;
A second cooling circuit in which cooling water circulates in the order of an electric water pump, the water-cooled heat exchanger, the radiator, and the electric water pump;
The flow path of the cooling water flowing to the water-cooled heat exchanger, the first cooling circuit when the outlet temperature of the cooling water at the outlet of the mechanical water pump is lower than the intake temperature of the intake at the outlet of the turbocharger And the cooling circuit switching mechanism for switching to the second cooling circuit and driving the electric water pump when the outlet temperature is equal to or higher than the intake air temperature. Engine cooling system characterized by The cooling circuit switching mechanism comprises: a first valve interposed between the mechanical water pump of the first cooling circuit and the water-cooled heat exchanger; and the mechanical water pump from the water-cooled heat exchanger And a control device for controlling the drive of the electric water pump and controlling the opening degree of the first valve and the second valve, respectively.
The control device performs control to compare the outlet temperature with the intake air temperature, and stops the electric water pump when the outlet temperature is less than the intake air temperature. The first valve is opened. An opening degree and an opening-side opening degree of the second valve are respectively controlled, while the electric water pump is driven when the outlet temperature is equal to or higher than the intake temperature, the first valve The engine cooling device according to claim 1, wherein control is performed to set the opening degree of the closed side and the opening degree of the closed side of the second valve.   A third valve is disposed either before or after the electric water pump, and the control device performs control to make the third valve an opening degree on the closing side when the electric water pump is stopped. 3. The engine cooling device according to claim 2, wherein when the electric water pump is driven, control is performed to make the third valve open. A thermostat is interposed between the outlet of the main cooling circuit from the engine body and the radiator, and a fourth valve is interposed between the radiator and the mechanical water pump.
When the outlet temperature is less than the intake temperature, the controller performs control to bring the fourth valve to an opening on the closed side, and when the outlet temperature is higher than the intake temperature, the fourth control is performed. The engine cooling device according to claim 2 or 3, wherein control is performed to make the valve open.   The water-cooled heat exchanger of the first cooling circuit and the mechanical water pump are connected via the thermostat, and between the water-cooled heat exchanger of the first cooling circuit and the thermostat The engine cooling device according to claim 4, wherein the second valve is interposed. A thermostat is interposed between the radiator of the main cooling circuit and the inlet to the engine body, and a fourth valve is interposed between the engine body and the radiator.
When the outlet temperature is less than the intake temperature, the controller performs control to bring the fourth valve to an opening on the closed side, and when the outlet temperature is higher than the intake temperature, the fourth control is performed. The engine cooling device according to claim 2 or 3, wherein control is performed to make the valve open. Map data in which the first region where the outlet temperature is lower than the intake temperature and the second region where the outlet temperature is higher than the intake temperature are set in the control device based on the engine speed and the engine output torque Equipped with
Instead of performing control to compare the outlet temperature with the intake air temperature, the control device performs control to compare the operating state of the engine main body with the map data, and the operating state of the engine main body In the case of the first region, control is performed such that the first valve is at the opening side and the second valve is at the opening side, while in the case of the second region, The control according to any one of claims 2 to 6, wherein control is performed such that the first valve has an opening on the closing side and the second valve has an opening on the opening side. Engine cooling system.   The control system according to any one of claims 2 to 7, wherein, when the operation of the engine body is stopped, the control device performs control to make the first valve and the second valve open. Cooling device for an engine according to claim 1.   The engine according to any one of claims 1 to 8, wherein the cooling circuit switching mechanism is configured to switch the flow path of the sub cooling circuit to the first cooling circuit during warm-up of the engine body. Cooling system. The cooling water is circulated in the order of the mechanical water pump, the engine body, the radiator and the bypass passage bypassing the radiator, and the mechanical water pump in order to cool the engine body and the cooling water. In a method of cooling an engine, which circulates to a water-cooled heat exchanger for cooling intake air supercharged by a turbocharger to cool the water-cooled heat exchanger,
When the outlet temperature of the cooling water at the outlet of the mechanical water pump is lower than the intake temperature of the intake air at the outlet of the turbocharger, the cooling water may be the mechanical water pump, the water-cooled heat exchanger, and the machine The water-cooled heat exchanger is cooled by circulating in the order of a water pump.
When the outlet temperature is equal to or higher than the intake temperature, the electric water pump is driven to circulate cooling water in the order of the electric water pump, the water-cooled heat exchanger, the radiator, and the electric water pump. A method of cooling an engine comprising cooling a water-cooled heat exchanger.