Engine System

Abstract

To adjust a wall temperature of a combustion chamber with high responsiveness in accordance with a load of an engine.SOLUTION: An engine system 1 includes an engine 10, a circulation device 91 for circulating cooling water to a water jacket 20, and a controller (ECU 100). The circulation device includes a radiator flow passage 53 including a heat exchanger (radiator 27), a bypass flow passage 51, a flow control device (cooling water control valve 4), and a thermostat valve 28. The controller controls the flow control device so that a flow rate of the cooling water flowing in the water jacket is adjusted in accordance with a load of the engine by closing the radiator flow passage and adjusting a flow rate of the cooling water flowing through the bypass flow passage when the load is lower than a first load, and controls the flow control device so that the cooling water flows in the radiator flow passage and the bypass flow passage when the load is equal to or higher than the first load.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to engine systems. [Background technology]

[0002] Patent Document 1 discloses an engine cooling device. This cooling device has a radiator path (23, the symbol shown in the specification; the same applies below) that circulates cooling water between the engine and a radiator, and a radiator bypass path (24) that circulates the cooling water bypassing the radiator. A heater core (31) of an air conditioner and an ATF warmer (32) that warms lubricating oil for an automatic transmission are disposed in the radiator bypass path (24).

[0003] The cooling device has a rotary flow control valve (50). The rotary flow control valve (50) opens and closes the radiator path (23) and the radiator bypass path (24) depending on the rotational position of a rotary valve element (51). The rotary flow control valve (50) also has a radiator path connection path (71) and a thermostat valve installation path (72). The radiator path connection path (71) is connected to the radiator path (23). A thermostat valve (40) is provided in the thermostat valve installation path (72). When the thermostat valve 40 is open, the coolant flows from the thermostat valve installation path (72) to the radiator path (23).

[0004] When the engine is warm and the temperature of the cooling water has reached a predetermined temperature or higher, the rotary flow control valve (50) rotates the rotary valve element (51) to a rotational position such that the cooling water flows through both the radiator bypass path (24) and the thermostat valve installation path (72). When the engine is warm, the thermostat valve (40) opens, and the cooling water flows from the thermostat valve installation path (72) to the radiator path (23).

[0005] When the temperature of the cooling water further increases, the rotary flow control valve (50) changes the rotational position of the rotary valve element (51) to a rotational position that allows the cooling water to flow through all of the radiator bypass path (24), the thermostat valve installation path (72), and the radiator path connection path (71). Moreover, the rotational position of the rotary valve element (51) is adjusted so that the flow rate of the cooling water into the radiator path (23) increases as the cooling water temperature, the engine load, and / or the engine speed increases. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2016-128652 A Summary of the Invention [Problem to be solved by the invention]

[0007] After the engine is completely warmed up, the combustion chamber becomes hot. To cool the combustion chamber, as in the cooling device of Patent Document 1, a flow path through which cooling water cooled by a radiator flows, that is, a so-called water jacket, is provided around the combustion chamber in the cylinder bore, cylinder head, etc. that constitute the main body of the engine.

[0008] Incidentally, in engine combustion control, the temperature inside the combustion chamber (in-cylinder temperature) is one of the important factors. The more advanced the combustion control, the more precise control of the in-cylinder temperature is required. For example, to stably control compression ignition combustion, it is necessary to control the in-cylinder temperature at a higher temperature than spark ignition combustion, and with high precision. In addition, the amount of heat generated in the combustion chamber changes depending on the engine load, so the in-cylinder temperature also changes.

[0009] In controlling the in-cylinder temperature, the wall temperature of the combustion chamber is one of the important factors. It is required to adjust the wall temperature of the combustion chamber with good responsiveness to changes in the engine load.

[0010] In this regard, the cooling device of Patent Document 1 lowers the temperature of the cooling water by increasing the flow rate of the cooling water flowing through the radiator path when the temperature of the cooling water becomes high. When the temperature of the cooling water changes, the amount of heat exchanged between the cooling water and the combustion chamber changes. By changing the amount of heat exchange according to the amount of heat generated in the combustion chamber, the wall temperature of the combustion chamber can be adjusted.

[0011] However, because the heat capacity of the cooling water is large, it takes a long time to change the temperature of the cooling water. It is difficult to adjust the wall temperature of the combustion chamber with good responsiveness to changes in the engine load by adjusting the temperature of the cooling water.

[0012] The technology disclosed herein adjusts the wall temperature of the combustion chamber with high responsiveness in response to the engine load. [Means for solving the problem]

[0013] The inventors of the present application focused on the fact that, rather than changing the temperature of the cooling water, the flow rate of the cooling water flowing through the water jacket can be changed to change the heat transfer coefficient between the cooling water and the combustion chamber, thereby adjusting the wall temperature of the combustion chamber, and completed the technology disclosed herein.

[0014] The technology disclosed herein relates to an engine system, An engine having a water jacket disposed around a combustion chamber; a circulation device attached to the engine and configured to circulate cooling water through the water jacket; a controller that controls the circulation device in accordance with an operating state of the engine; The circulation device includes: a radiator flow path including a heat exchanger; a bypass flow path that bypasses the heat exchanger; a flow rate adjusting device that adjusts a flow rate of the cooling water flowing through the water jacket by adjusting a flow rate of the cooling water flowing through each of the radiator flow path and the bypass flow path; a thermostat valve connected to the radiator flow path and opening to allow the coolant to pass through the heat exchanger; The controller is electrically connected to the flow control device and When a load of the engine is lower than a first load, the flow rate control device is controlled to close the radiator flow path and adjust a flow rate of the cooling water flowing through the bypass flow path to adjust a flow rate of the cooling water flowing through the water jacket in accordance with the load; and When the load is equal to or greater than the first load, the flow rate control device is controlled so that the cooling water flows through both the radiator passage and the bypass passage.

[0015] According to this configuration, the cooling water passing through the water jacket of the engine exchanges heat with the combustion chamber. The cooling water is circulated through the water jacket by the circulation device.

[0016] The circulation device has a thermostatic valve that opens when the cooling water is at a predetermined temperature. When the thermostatic valve opens, a portion of the cooling water passes through the heat exchanger, lowering the temperature of the cooling water. The thermostatic valve maintains the temperature of the cooling water at a specific temperature that corresponds to the opening temperature of the thermostatic valve.

[0017] When the engine load is lower than the first load, the flow rate control device closes the radiator flow path. The coolant flows through the bypass flow path. The flow rate control device also adjusts the flow rate of the coolant, thereby changing the flow rate of the coolant flowing through the water jacket. Because the flow rate control device can change the flow rate of the coolant more quickly than the temperature of the coolant, the flow rate control device can adjust the flow rate of the coolant flowing through the water jacket with high responsiveness to changes in load.

[0018] When the flow rate of the cooling water flowing through the water jacket decreases, the heat transfer coefficient decreases, and when the flow rate of the cooling water flowing through the water jacket increases, the heat transfer coefficient increases. The amount of heat generated in the combustion chamber changes depending on the engine load. Therefore, in the above engine system, the controller changes the flow rate of the cooling water flowing through the water jacket through the flow rate adjustment device depending on the engine load, so that the wall temperature of the combustion chamber can be adjusted with high responsiveness.

[0019] When the engine load is equal to or greater than the first load, the amount of heat generated in the combustion chamber increases relatively. The controller controls the flow rate control device to allow the coolant to flow through both the radiator passage and the bypass passage. For example, the temperature of the coolant is reduced by increasing the flow rate of the coolant flowing through the radiator passage. When the engine load is equal to or greater than the first load, the wall temperature of the combustion chamber becomes appropriate.

[0020] The controller may increase a flow rate of the cooling water flowing through the water jacket when the load is high and the load is lower than the first load, compared to when the load is low.

[0021] When the engine load increases, the amount of heat generated in the combustion chamber increases. When the load is high, the flow rate of the cooling water flowing through the water jacket increases compared to when the load is low, increasing the heat transfer coefficient. The wall temperature of the combustion chamber is maintained at an appropriate temperature.

[0022] The controller may adjust the temperature of the cooling water flowing through the water jacket in accordance with the load by adjusting the flow rate of the cooling water flowing through the bypass flow path and the flow rate of the cooling water flowing through the radiator flow path when the load is equal to or greater than the first load.

[0023] When the flow rate of the cooling water flowing through the radiator passage increases, the temperature of the cooling water drops. As the load increases, the amount of heat generated in the combustion chamber increases, but the temperature of the cooling water flowing through the water jacket is adjusted according to the load, so the wall temperature of the combustion chamber is kept at an appropriate temperature.

[0024] When the load is equal to or greater than the first load, the controller may reduce the flow rate of the cooling water flowing through the bypass passage and increase the flow rate of the cooling water flowing through the radiator passage when the load is high, compared to when the load is low.

[0025] When the flow rate of the cooling water flowing through the radiator passage increases, the temperature of the cooling water decreases. When the load is high and the amount of heat generated in the combustion chamber is high, the cooling water temperature decreases, and the wall temperature of the combustion chamber becomes appropriate. Conversely, when the flow rate of the cooling water flowing through the radiator passage decreases, the cooling water temperature increases. When the load is low and the amount of heat generated in the combustion chamber is low, the cooling water temperature increases, and the wall temperature of the combustion chamber becomes appropriate.

[0026] The controller may set a flow rate of the cooling water flowing through the water jacket to a maximum flow rate when the load is equal to or greater than the first load.

[0027] When the load exceeds the first load, the amount of heat generated in the combustion chamber increases. By setting the flow rate of the cooling water flowing through the water jacket to the maximum, the wall temperature of the combustion chamber becomes appropriate when the amount of heat generated in the combustion chamber is high.

[0028] The controller may maintain a wall temperature of the combustion chamber at a constant temperature when the load is lower than the first load and when the load is equal to or higher than the first load.

[0029] The ideal wall temperature of the combustion chamber when the engine load is low does not necessarily match the ideal wall temperature of the combustion chamber when the engine load is high. Ideally, the wall temperature of the combustion chamber should be changed depending on the load. However, since the wall of the combustion chamber has a large heat capacity, it is difficult to raise or lower the temperature of the wall of the combustion chamber in a short period of time.

[0030] Therefore, the above-mentioned configuration maintains the wall temperature of the combustion chamber at a specific temperature that is tolerable when the load is lower than the first load and when the load is equal to or higher than the first load. Specifically, when the load is lower than the first load, the flow rate of the cooling water flowing through the water jacket is adjusted according to the load while the cooling water is kept at a constant temperature using a thermostat valve, thereby maintaining the wall temperature of the combustion chamber at a specific temperature. When the load is equal to or higher than the first load, the flow rate of the cooling water flowing through the bypass flow passage and the flow rate of the cooling water flowing through the radiator flow passage are adjusted to adjust the temperature of the cooling water flowing through the water jacket according to the load, thereby maintaining the wall temperature of the combustion chamber at the same specific temperature. As a result, even when the engine load is lower than the first load or equal to or higher than the first load, the wall temperature of the combustion chamber is at an appropriate temperature.

[0031] The controller may be configured to reduce a temperature of the cooling water flowing through the water jacket below a valve opening temperature of the thermostat valve when the load is equal to or greater than the first load.

[0032] When the engine load is high, a lot of heat is generated in the combustion chamber. The temperature of the cooling water flowing through the water jacket is relatively lowered, allowing the wall temperature of the combustion chamber to be at an appropriate temperature.

[0033] When the engine load is low, the amount of heat generated in the combustion chamber is small. When the load is lower than the first load, the temperature of the cooling water is determined by the opening temperature of the thermostat valve, as described above. By setting the opening temperature of the thermostat valve to a relatively high temperature, the temperature of the cooling water flowing through the water jacket increases relatively, so that the wall temperature of the combustion chamber can be kept at an appropriate temperature.

[0034] The controller may be configured to increase a flow rate of the cooling water flowing through the radiator flow passage so that a temperature of the cooling water flowing through the water jacket decreases as the load increases when the load is equal to or greater than the first load and lower than a second load, and to increase a flow rate of the cooling water flowing through the radiator flow passage so that a temperature of the cooling water flowing through the water jacket remains constant as the load increases when the load is equal to or greater than the second load.

[0035] When the load is equal to or greater than the first load but lower than the second load, i.e., medium load, as the load increases, the temperature of the cooling water flowing through the water jacket decreases. The wall temperature of the combustion chamber can be maintained at a constant temperature regardless of the increase in load. When the load is equal to or greater than the second load, i.e., high load, the temperature of the cooling water flowing through the water jacket becomes constant regardless of the increase in load. The wall temperature of the combustion chamber can be maintained at an appropriate temperature.

[0036] The engine may have an ignition device that forcibly ignites the mixture, and when the load is lower than the first load, the mixture in the combustion chamber may be burned without forced ignition by the ignition device, and when the load is equal to or greater than the first load, the mixture in the combustion chamber may be burned by forced ignition by the ignition device.

[0037] When the mixture in the combustion chamber burns without forced ignition, that is, when it burns by self-ignition, the thermal efficiency of the engine is improved and the wall temperature of the combustion chamber tends to be low, but from the viewpoint of stabilizing combustion, it is preferable to maintain the wall temperature of the combustion chamber at a relatively high temperature. As described above, the temperature of the cooling water flowing through the water jacket may be relatively increased and the wall temperature of the combustion chamber may be increased by setting the opening temperature of the thermostat valve at a relatively high temperature.

[0038] As mentioned above, the flow rate of the cooling water flowing through the water jacket is adjusted according to the load. This changes the heat transfer coefficient according to the amount of heat generated in the combustion chamber, and the wall temperature of the combustion chamber is maintained at an appropriate temperature.

[0039] When the mixture in the combustion chamber is burned by forced ignition, the wall temperature of the combustion chamber becomes relatively high due to a decrease in thermal efficiency, and if the wall temperature of the combustion chamber becomes too high, there is a risk of abnormal combustion such as knocking. Therefore, when the mixture in the combustion chamber is burned by forced ignition, the controller controls the flow rate adjustment device so that the cooling water flows through both the radiator flow path and the bypass flow path. This relatively lowers the temperature of the cooling water, so that the wall temperature of the combustion chamber can be made appropriate.

[0040] The flow rate control device is installed at a location where the bypass flow path and the radiator flow path branch off or at a location where the bypass flow path and the radiator flow path join together, The circulation device further includes a communication passage that communicates the bypass passage and the radiator passage, The thermostatic valve may open and close the communication passage.

[0041] According to this configuration, when the temperature of the cooling water rises and the thermostatic valve opens while the radiator passage is closed, the cooling water flows from the bypass passage to the radiator passage. The temperature of the cooling water drops. The thermostatic valve can maintain the cooling water at a predetermined temperature.

[0042] The flow rate control device is installed at a location where the bypass flow path and the radiator flow path branch off or at a location where the bypass flow path and the radiator flow path join together, The circulation device further includes a communication passage that bypasses the flow rate adjustment device and connects the water jacket and the radiator passage, The thermostatic valve may open and close the communication passage.

[0043] With this configuration, when the temperature of the cooling water rises and the thermostatic valve opens while the radiator passage is closed by the flow rate control device, the cooling water bypasses the flow rate control device and flows into the radiator passage. The temperature of the cooling water drops. Even in this case, the thermostatic valve can maintain the cooling water at a predetermined temperature.

[0044] The flow rate control device is a housing provided with a first port connected to the bypass flow path, a second port connected to the radiator flow path, and a third port connected to each of the first port and the second port; a rotary valve body that is rotatably accommodated in the housing, that is interposed between the first port, the second port, and the third port, and that has a first water passage opening that is connected to the first port and a second water passage opening that is connected to the second port; an actuator that adjusts the flow rate of cooling water flowing through each of the first port and the second port by rotating the rotary valve body to change the opening degree of each of the first water passage opening and the second water passage opening; It may also be said that the inventive subject has the following characteristics.

[0045] The flow control device having a rotary valve body can selectively close the bypass passage and / or the radiator passage and can adjust the flow rate of the bypass passage and the flow rate of the radiator passage. The engine system equipped with the flow control device can achieve the above-mentioned flow rate adjustment of the water jacket with a simple configuration. Effect of the Invention

[0046] As described above, according to the engine system, the wall temperature of the combustion chamber can be adjusted with high responsiveness in accordance with the engine load. [Brief description of the drawings]

[0047] [Figure 1] FIG. 1 illustrates an exemplary engine system. [Diagram 2] FIG. 2 is a block diagram of an exemplary engine system. [Diagram 3] FIG. 3 illustrates an example control map for an engine system. [Figure 4] FIG. 4 illustrates an exemplary circulation device. [Diagram 5] FIG. 5 illustrates an exemplary flow regulator. [Figure 6] FIG. 6 illustrates an exemplary control of a circulation device. [Figure 7] FIG. 7 illustrates an exemplary control of a circulation device. [Figure 8] FIG. 8 shows an exemplary control procedure for the circulation device. [Figure 9] FIG. 9 shows an exemplary control procedure for the circulation device. [Figure 10] FIG. 10 illustrates an exemplary circulation device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an engine system will be described below with reference to the drawings. The engine system described here is merely an example.

[0049] (Example of engine system configuration) 1 and 2 show a configuration example of an engine system 1. The engine system 1 is mounted on an automobile. The engine system 1 includes an engine 10, which is an internal combustion engine. When the engine 10 is operating, the automobile moves. The automobile may be an automobile equipped with only the engine 10 as a power source for moving, or may be a hybrid automobile equipped with the engine 10 and an electric motor.

[0050] The engine 10 includes a cylinder block 11 and a cylinder head 12. A plurality of cylinders 13 are formed in the cylinder block 11. The engine 10 is a multi-cylinder engine.

[0051] The multiple cylinders 13 are aligned in a row along the crankshaft 14 (see also FIG. 4). A piston 15 is inserted into each cylinder 13. The piston 15 is connected to the crankshaft 14 via a connecting rod 151. The piston 15, the cylinder 13, and the cylinder head 12 form a combustion chamber 16.

[0052] An intake port 121 communicating with each cylinder 13 is formed in the cylinder head 12. An intake valve 122 disposed in the intake port 121 opens and closes the intake port 121. An intake valve train 123 (see FIG. 2) opens and closes the intake valve 122 at a predetermined timing. The intake valve train 123 is a variable valve train that varies the valve timing and / or the valve lift.

[0053] An exhaust port 124 communicating with each cylinder 13 is formed in the cylinder head 12. An exhaust valve 125 disposed in the exhaust port 124 opens and closes the exhaust port 124. An exhaust valve train 126 opens and closes the exhaust valve 125 at a predetermined timing. The exhaust valve train 126 is a variable valve train that makes the valve timing and / or the valve lift variable.

[0054] An injector 131 is attached to the cylinder head 12 for each cylinder 13. The injector 131 directly injects fuel into the cylinder 13. An ignition plug 132 is attached to the cylinder head 12 for each cylinder 13. The ignition plug 132 forcibly ignites the air-fuel mixture in the cylinder 13.

[0055] An intake passage 17 is connected to one side of the engine 10. The intake passage 17 is connected to an intake port 121. A throttle valve 171 is disposed in the intake passage 17. The throttle valve 171 adjusts the amount of air introduced into the cylinder 13. An exhaust passage 18 is connected to the other side of the engine 10. The exhaust passage 18 is connected to an exhaust port 124.

[0056] An EGR passage 19 is connected between the intake passage 17 and the exhaust passage 18. The EGR passage 19 recirculates a portion of the exhaust gas to the intake passage 17. An EGR cooler 191 is disposed in the EGR passage 19. The EGR cooler 191 cools the exhaust gas. An EGR valve 192 is also disposed in the EGR passage 19. The EGR valve 192 adjusts the flow rate of the exhaust gas flowing through the EGR passage 19.

[0057] The engine system 1 includes an ECU (Engine Control Unit) 100 for operating an engine 10. The ECU 100 is a controller based on a known microcomputer, and includes a central processing unit (CPU) 101, a memory 102, and an I / F circuit 103. The CPU 101 executes a program. The memory 102 is configured, for example, by a RAM (Random Access Memory) or a ROM (Read Only Memory) and stores programs and data. The I / F circuit 103 inputs and outputs electric signals. The ECU 100 is an example of a controller.

[0058] Various sensors SN1 to SN5 are connected to the ECU 100. The sensors SN1 to SN5 output signals to the ECU 100. The sensors include the following sensors. First water temperature sensor SN1: outputs a signal corresponding to the temperature of the cooling water flowing into the engine 10 in a cooling water circulation device 91 described later. A second water temperature sensor SN2 is attached to the engine 10 and outputs a signal corresponding to the temperature of the cooling water flowing through the engine 10. In-cylinder pressure sensor SN3: attached to the cylinder head 12 and outputs a signal corresponding to the pressure in each cylinder 13. Crank angle sensor SN4: attached to the engine 10 and outputs a signal corresponding to the rotation angle of the crankshaft 14. Accelerator opening sensor SN5: Attached to the accelerator pedal mechanism, outputs a signal corresponding to the amount of accelerator pedal operation.

[0059] The ECU 100 judges the operating state of the engine 10 based on the signals of these sensors SN1 to SN5, and calculates the control amount of each device according to a predetermined control logic. The control logic is stored in the memory 102. The control logic includes calculating a target amount and / or a control amount by using a map stored in the memory 102. The ECU 100 outputs an electric signal related to the calculated control amount to the injector 131, the spark plug 132, the intake valve train 123, the exhaust valve train 126, the throttle valve 171, the EGR valve 192, and a cooling water control valve 4 described later.

[0060] More specifically, the ECU 100 has a load calculation unit 104, a combustion type determination unit 105, a water temperature determination unit 106, and a CCV control unit 107 as functional blocks.

[0061] The load calculation unit 104 calculates a target load of the engine 10 based on the output signal of the accelerator opening sensor SN5. The combustion mode determination unit 105 determines the operating region of the engine 10 in a base map 301 (see FIG. 3) described later based on the load of the engine 10 and the output signal of the crank angle sensor SN4, and determines the combustion mode corresponding to the operating region. The water temperature determination unit 106 determines the temperature of the cooling water flowing through the water jacket 20 (see FIG. 4) around the combustion chamber 16 based on the output signal of the second water temperature sensor SN2. The CCV control unit 107 cools the engine 10 by controlling the cooling water control valve 4 according to the operating state of the engine 10.

[0062] (Engine operation control map) 3 illustrates a base map 301 related to the control of the engine 10. The base map 301 is stored in the memory 102 of the ECU 100. The illustrated base map 301 is the base map 301 when the engine 10 is completely warmed up.

[0063] The base map 301 is defined by the load and the rotation speed of the engine 10. The base map 301 is roughly divided into four regions according to the high and low loads and the high and low rotation speeds. More specifically, the first region 311 includes a region from low load to high load at high rotation speed and a region of high load at low and medium rotation speed. The second region 312 is a region of low load at low and medium rotation speed. The third region 313 is a region of low to medium load at low and medium rotation speed. The fourth region 314 is a region of medium to high load at low and medium rotation speed. The low rotation speed region, the medium rotation speed region, and the high rotation speed region may be respectively the low rotation speed region, the medium rotation speed region, and the high rotation speed region when the entire operating region of the engine 10 is divided into approximately three equal parts in the rotation speed direction into the low rotation speed region, the medium rotation speed region, and the high rotation speed region.

[0064] Next, the operation of the engine 10 in each region will be briefly described. The ECU 100 determines the operating region according to the target load for the engine 10 and the engine speed of the engine 10, and according to the determined operating region, the ECU 100 changes the opening and closing operation of the intake valve 122 and the exhaust valve 125, the fuel injection timing, and the presence or absence of forced ignition. As a result, the combustion mode of the engine 10 changes to SI (Spark Ignition) combustion, HCCI (Homogeneous Charge Compression Ignition) combustion, MPCI (Multiple Premixed fuel injection Compression Ignition) combustion, and SPCCI (Spark Controlled Compression Ignition) combustion.

[0065] (SI Combustion) When the operating state of the engine 10 is in the first region 311, the ECU 100 causes the mixture in the cylinder 13 to undergo flame propagation and combustion. The intake valve train 123 opens the intake valve 122 at a predetermined timing and / or with a predetermined lift amount, and the exhaust valve train 126 opens the exhaust valve 125 at a predetermined timing and / or with a predetermined lift amount. The injector 131 injects fuel into the cylinder 13 during the intake stroke and / or the compression stroke. The spark plug 132 ignites the mixture near the top dead center of the compression stroke.

[0066] (HCCI combustion) When the operating state of the engine 10 is in the second region 312, the ECU 100 causes the mixture in the cylinder 13 to undergo compression ignition and combustion. The intake valve train 123 opens the intake valve 122 at a predetermined timing and / or with a predetermined lift amount, and the exhaust valve train 126 opens the exhaust valve 125 at a predetermined timing and / or with a predetermined lift amount. The injector 131 injects fuel into the cylinder 13 during the intake stroke. The spark plug 132 does not ignite the mixture. The mixture undergoes compression autoignition and burns near the top dead center of compression.

[0067] (MPCI Combustion) When the operating state of the engine 10 is in the third region 313, the ECU 100 causes the mixture in the cylinder 13 to undergo compression ignition and combustion. The intake valve train 123 opens the intake valve 122 at a predetermined timing and / or with a predetermined lift amount, and the exhaust valve train 126 opens the exhaust valve 125 at a predetermined timing and / or with a predetermined lift amount. The injector 131 injects fuel into the cylinder 13 during the intake stroke and during the compression stroke. The injector 131 performs split injection. The spark plug 132 does not ignite the mixture. The mixture undergoes compression auto-ignition and burns near the top dead center of compression.

[0068] Split injection creates a non-homogenous mixture in the cylinder 13. In this respect, MPCI combustion differs from HCCI combustion, which creates a homogeneous mixture. MPCI combustion makes it possible to control the timing of compression ignition when the load of the engine 10 is relatively high.

[0069] (SPCCI Combustion) When the operating state of the engine 10 is in the fourth region 314, the ECU 100 causes a part of the mixture in the cylinder 13 to undergo flame propagation combustion, and causes the remaining part to undergo compression ignition combustion. The intake valve train 123 opens the intake valve 122 at a predetermined timing and / or with a predetermined lift amount, and the exhaust valve train 126 opens the exhaust valve 125 at a predetermined timing and / or with a predetermined lift amount. The injector 131 injects fuel into the cylinder 13 during the compression stroke. The spark plug 132 ignites the mixture near the compression top dead center. The mixture starts flame propagation combustion. The temperature in the cylinder 13 increases due to heat generated by the combustion, and the pressure in the cylinder 13 increases due to flame propagation. As a result, the unburned mixture undergoes compression autoignition, for example, after the compression top dead center, and starts to burn. After the compression ignition combustion starts, the flame propagation combustion and the compression ignition combustion proceed in parallel.

[0070] (Circulation system configuration) Next, the configuration of the circulation device 91 of the engine system 1 will be described with reference to Fig. 4. The circulation device 91 is attached to the engine 10, and is a device that circulates the cooling water through the water jacket 20.

[0071] The water jacket 20 is formed inside the engine 10. The water jacket 20 is connected to a circulation device 91, and together with the circulation device 91, forms a circuit through which the cooling water circulates. The water jacket 20 has an in-block jacket 21 and an in-head jacket 22. The in-block jacket 21 is formed in the cylinder block 11 so as to extend along the outer periphery of each cylinder 13.

[0072] The head jacket 22 is formed in the cylinder head 12. The head jacket 22 communicates with the block jacket 21 (see the dotted line in FIG. 4). The head jacket 22 has a first jacket 22a and a second jacket 22b. The first jacket 22a and the second jacket 22b are independent of each other.

[0073] The first jacket 22a is formed to extend along the upper portions of the multiple combustion chambers 16 arranged in a row. The cooling water flowing through the first jacket 22a mainly exchanges heat with (mainly cools) the combustion chambers 16. In detail, the cooling water flowing through the first jacket 22a exchanges heat with the atmosphere in the combustion chambers 16 via the wall surfaces of the combustion chambers 16.

[0074] The second jacket 22b is formed to extend along the periphery of the exhaust ports 124 of the multiple cylinders 13 arranged in a row. The cooling water flowing through the second jacket 22b mainly exchanges heat (mainly cools) with the exhaust ports 124 through which high-temperature exhaust gas flows.

[0075] A water pump 3 is provided in a cylinder block 11 at an end (inlet end 10a) of the engine 10. The water pump 3 constitutes a part of a circulation device 91.

[0076] The water pump 3 is a mechanical pump in which a rotating shaft of the pump is connected to the crankshaft 14 of the engine 10 via a pulley, a belt, etc. The water pump 3 is operated by the driving force of the engine 10. However, the water pump 3 may be an electric pump that can be operated independently of the engine 10.

[0077] The intra-block jacket 21 is connected to the discharge port 3a of the water pump 3 via a cooling water inlet passage 23. Therefore, the cooling water discharged by the water pump 3 flows into the intra-block jacket 21 through the cooling water inlet passage 23. The cooling water that has flowed into the intra-block jacket 21 flows into the intra-head jacket 22. In detail, the cooling water is divided and flows into the first jacket 22a and the second jacket 22b.

[0078] A coolant control valve 4 (CCV, which corresponds to the "flow rate regulator" in the disclosed technology) is provided in the cylinder head 12 at the end (outlet end 10b) opposite to the inlet end 10a of the engine 10. The coolant control valve 4 constitutes a part of the circulation device 91.

[0079] A third port 65 (see FIG. 5) of the cooling water control valve 4 is connected to the first jacket 22a via the first cooling water outlet passage 24. Therefore, the cooling water flowing through the first jacket 22a flows out of the engine 10 through the first cooling water outlet passage 24 and flows into the cooling water control valve 4 (the cooling water control valve 4 will be described in detail later).

[0080] A second cooling water outlet passage 25 communicating with the second jacket 22b is formed in a portion of the exhaust side of the cylinder head 12 at the outlet end 10b. Therefore, the cooling water flowing through the second jacket 22b flows out of the engine 10 through the second cooling water outlet passage 25 and flows into a second circulation passage 31, which will be described later.

[0081] A third cooling water outlet passage 26 communicating with the block inner jacket 21 is formed in a portion of the intake side of the cylinder block 11 at the outlet end 10b. Therefore, a portion of the cooling water flowing through the block inner jacket 21 flows out of the engine 10 through the third cooling water outlet passage 26 and into a third circulation passage 41, which will be described later.

[0082] The circulation device 91 includes, in addition to the above-mentioned water pump 3 and coolant control valve 4, a radiator 27 (corresponding to the "heat exchanger" in the disclosed technology) and a thermostat valve 28. The engine system 1 including the circulation device 91 is broadly divided into a second circuit 30, a third circuit 40, and a first circuit 50 as flow paths through which the coolant circulates.

[0083] (2nd circuit) The second circuit 30 has a second circulation flow path 31 provided with two branched flow paths (a first branch flow path 31a and a second branch flow path 31b). An EGR cooler 191 and a heater 71 are arranged in the first branch flow path 31a. The heater 71 is incorporated in an air conditioner that adjusts the air in the vehicle cabin. A throttle valve (Electric Throttle Body: ETB) 171 and an EGR valve 192 are arranged in the second branch flow path 31b. An upstream end of the second circulation flow path 31 is connected to the second coolant discharge path 25. A downstream end of the second circulation flow path 31 is connected to the suction port 3b of the water pump 3 in a state where it merges with the first circuit 50 and the third circuit 40.

[0084] Inside the engine 10, the block inner jacket 21, the second jacket 22b, and the second coolant discharge passage 25 form a flow path of the second circuit 30. Therefore, in the second circuit 30, the coolant discharged from the water pump 3 flows through the block inner jacket 21 and the second jacket 22b, and then branches off to flow into each of the first branch passage 31a and the second branch passage 31b. Then, after merging, the coolant flows back to the water pump 3.

[0085] The coolant flowing through the second circuit 30 exchanges heat mainly with the exhaust port 124 of the engine 10. The coolant also exchanges heat with the EGR cooler 191, the heater 71, the throttle valve 171, and the EGR valve 192.

[0086] (3rd circuit) The third circuit 40 has a third circulation flow path 41 in which an oil cooler 72 and an ATF heat exchanger 73 are installed. The oil cooler 72 is installed in a system that circulates and supplies lubricating oil to the engine 10. The ATF heat exchanger 73 is installed in a system that circulates and supplies hydraulic oil for an automatic transmission. An upstream end of the third circulation flow path 41 is connected to the third coolant outlet path 26. A downstream end of the third circulation flow path 41 is connected to the suction port 3b of the water pump 3 in a state where it merges with the first circuit 50 and the second circuit 30.

[0087] Inside the engine 10, the block inner jacket 21 and the third coolant outlet passage 26 form a flow path of a third circuit 40. Therefore, in the third circuit 40, of the coolant discharged from the water pump 3, a part of the coolant flowing through the block inner jacket 21 flows through the third circulation passage 41 and returns to the water pump 3. The coolant flowing through the third circuit 40 exchanges heat with an oil cooler 72 and an ATF heat exchanger 73.

[0088] (1st circuit) The first circuit 50 has a bypass passage 51, a communication passage 52, and a radiator passage 53. Inside the engine 10, the block inner jacket 21, the first jacket 22a, and the first coolant discharge passage 24 configure the passage of the first circuit 50.

[0089] The flow path of the first circuit 50 branches into a bypass flow path 51 and a radiator flow path 53 at the coolant control valve 4. The downstream ends of the bypass flow path 51 and the radiator flow path 53 are connected to the suction port 3b of the water pump 3 while merging with the second circuit 30 and the third circuit 40.

[0090] The radiator 27 is provided in the radiator flow path 53. The radiator 27 is installed behind the front grill of the vehicle. The cooling water flowing through the radiator 27 exchanges heat mainly with outside air caused by the running wind. The cooling water dissipates heat and is cooled by flowing through the radiator flow path 53.

[0091] As a result, the radiator flow path 53 cools the cooling water discharged from the water pump 3, which flows through the block inner jacket 21 and the first jacket 22a and is heated by heat exchange, in the radiator 27, and returns the water to the block inner jacket 21 and the first jacket 22a.

[0092] The bypass flow passage 51 is a flow passage that bypasses the radiator flow passage 53. The bypass flow passage 51 is shorter than the radiator flow passage 53. Only the thermostatic valve 28 is provided in the bypass flow passage 51. The thermostatic valve 28 is connected to the radiator flow passage 53 via the communication flow passage 52 in a state in which the upstream side and the downstream side of the bypass flow passage 51 are always in communication with each other.

[0093] As a result, the bypass passage 51 returns the cooling water discharged from the water pump 3, which flows through the block inner jacket 21 and the first jacket 22a and exchanges heat, to the block inner jacket 21 and the first jacket 22a without being cooled by the radiator 27.

[0094] The thermostat valve 28 is a known device that opens and closes at a preset high temperature. The thermostat valve 28 has a valve body that is biased in a closing direction by the elastic force of a spring. The valve body is displaced by the action of wax, thereby opening and closing the thermostat valve 28. The opening temperature of the thermostat valve 28 of this engine system 1 is set higher than that of conventional thermostat valves.

[0095] When the thermostatic valve 28 opens, the bypass passage 51 communicates with the radiator passage 53 via the communication passage 52. Therefore, when the thermostatic valve 28 opens, a portion of the cooling water flowing through the bypass passage 51 passes through the communication passage 52 and flows into the radiator passage 53.

[0096] (Cooling water control valve) 5 shows the cooling water control valve 4. The cooling water control valve 4 is a valve capable of adjusting the flow rate of the cooling water, and is composed of a housing 60, a rotary valve body 61, an actuator 62, and the like.

[0097] A cylindrical flow dividing chamber 60a is provided inside the housing 60. A cylindrical rotary valve element 61 is rotatably accommodated in the flow dividing chamber 60a. A first port 63 and a second port 64 are formed in the housing 60 so as to extend radially outward from a predetermined position on the outer periphery of the flow dividing chamber 60a. The first port 63 is connected to the bypass flow passage 51. The second port 64 is connected to the radiator flow passage 53.

[0098] One end of the flow division chamber 60a is open. The opening defines a third port 65 through which the cooling water flows into the flow division chamber 60a. The housing 60 is attached to the cylinder head 12 so that the third port 65 is connected to the first cooling water outlet passage 24 with its center aligned. As a result, the peripheral wall of the rotary valve body 61 is interposed between the third port 65 and each of the first port 63 and the second port 64.

[0099] A first water passage opening 61a and a second water passage opening 61b are formed at predetermined positions on the peripheral wall of the rotary valve body 61. The first water passage opening 61a is longer in the circumferential direction than the second water passage opening 61b, and has a relatively large opening area. Depending on the rotational position of the rotary valve body 61, the third port 65 communicates with each of the first port 63 and the second port 64 via each of the first water passage opening 61a and the second water passage opening 61b, or does not communicate with each of them. Even when the third port 65 communicates with each of the first port 63 and the second port 64, the opening degree between the third port 65 and each of the first port 63 and the second port 64 changes depending on the rotational position of the rotary valve body 61.

[0100] The other end of the diversion chamber 60a is sealed by a sealing wall 66. An actuator 62 is accommodated inside the housing 60 on the opposite side of the sealing wall 66 to the diversion chamber 60a. A rotating shaft 62a of the actuator 62 protrudes into the diversion chamber 60a through a shaft hole that opens in the center of the sealing wall 66. A rotary valve element 61 is attached to the rotating shaft 62a protruding into the diversion chamber 60a via a support arm 62b. The ECU 100 outputs a control signal to the actuator 62. The ECU 100 controls the actuator 62, causing the rotary valve element 61 to rotate.

[0101] Returning to FIG. 4, the first water temperature sensor SN1 is disposed in a flow path where the first circuit 50, the second circuit 30, and the third circuit 40 join and flow into the water pump 3. The second water temperature sensor SN2 is disposed in the first jacket 22a. The first water temperature sensor SN1 measures the temperature of the coolant flowing into the engine 10. The second water temperature sensor SN2 measures the temperature of the coolant flowing through the water jacket 20, more precisely, the first jacket 22a. These sensors SN1 and SN2 are used for controlling the coolant and for controlling combustion. For example, the second water temperature sensor SN2 is used to estimate the wall temperature of the combustion chamber 16 when performing advanced combustion control. The second water temperature sensor SN2 is also used for controlling the actuator 62.

[0102] In this circulation device 91, the ECU 100 controls the coolant control valve 4 based on the measurement value of the second water temperature sensor SN2, thereby adjusting the flow rate of the coolant flowing through the first circuit 50, that is, the bypass flow path 51 and the radiator flow path 53 (the flow of the coolant in the communication flow path 52 is automatically adjusted by the thermostat valve 28).

[0103] The cooling water flowing through the circulation device 91 is mainly cooled by the radiator 27 installed in the radiator flow passage 53. The temperature of the cooling water is adjusted.

[0104] That is, the main component of this circulation device 91 is the first circuit 50. The flow rate and temperature of the cooling water in each of the second circuit 30 and the third circuit 40 change according to the adjustment of the flow rate and temperature of the cooling water in the first circuit 50. In this circulation device 91, the first circuit 50 is essential, but the second circuit 30 and the third circuit 40 are not essential.

[0105] (How to drain the cooling water) As described above, the cooling water flowing through the first jacket 22a mainly exchanges heat with the wall of the combustion chamber 16 to cool the wall of the combustion chamber 16. In this engine system 1, in order to stably and efficiently control the combustion of the engine 10, a plurality of cooling water flow patterns are set according to the temperature of the cooling water flowing through the first jacket 22a (the measured value of the second water temperature sensor SN2). Figure 6 shows the water flow state of each circuit in the engine system 1 according to the temperature of the cooling water.

[0106] In the cooling water control valve 4, the actuator 62 is controlled to adjust the flow rate of the cooling water flowing through both the first port 63 and the second port 64. That is, the opening degree of each of the first water passage opening 61a and the second water passage opening 61b is changed so that the rotary valve body 61 is in a predetermined rotation position.

[0107] "Low temperature" is a so-called cold state, such as immediately after the engine 10 is started. "Low temperature" is a state in which the temperature t of the cooling water flowing through the first jacket 22a is less than a first switching temperature t11 (e.g., 40°C). "Complete warm-up" is a state in which the engine 10 is warmed up to a temperature suitable for operation, and is a so-called warm state. "Complete warm-up" is a state in which the temperature t of the cooling water flowing through the first jacket 22a is equal to or higher than a second switching temperature t12 (e.g., 80°C). "Semi-warm-up" is a state between "low temperature" and "complete warm-up", that is, a transitional state. "Semi-warm-up" is a state in which the temperature t of the cooling water flowing through the first jacket 22a is equal to or higher than the first switching temperature t11 and lower than the second switching temperature t12, and is, for example, a state in which the temperature t of the cooling water is between 40°C and 80°C.

[0108] At "low temperature," as shown in state 81 on the left side of Fig. 6, no coolant flows through either the bypass passage 51 or the radiator passage 53 (the flow rates of both are zero). In other words, no coolant circulates through the first circuit 50. At this time, in the coolant control valve 4, the rotary valve element 61 is set to a rotation position where neither the first port 63 nor the second port 64 communicates with the third port 65.

[0109] Since no cooling water flows through the radiator flow passage 53, the cooling water is not cooled by the radiator 27. Therefore, the temperature of the cooling water rises quickly. Moreover, the combustion chamber 16 is not cooled by the circulation of the cooling water. The combustion chamber 16 can be quickly warmed by the heat of combustion. Since the engine 10 quickly reaches a temperature state suitable for combustion, fuel efficiency can be improved. At this time, the cooling water discharged by the water pump 3 circulates through the second circuit 30 and the third circuit 40.

[0110] During "semi-warm-up," as shown in state 82 in the center of Fig. 6, coolant flows through the bypass passage 51 but does not flow through the radiator passage 53 (the flow rate of the radiator passage 53 is zero). That is, in the first circuit 50, coolant circulates only through the bypass passage 51. At this time, in the coolant control valve 4, the rotary valve element 61 is set to a rotation position in which only the first port 63 communicates with the third port 65. The opening of the first water passage opening 61a is, for example, fully open.

[0111] Since the cooling water does not flow through the radiator passage 53, the temperature of the cooling water rises quickly. On the other hand, since the cooling water flows through the bypass passage 51, the cooling water flows into the first jacket 22a. The bypass passage 51 is short. Furthermore, since the cooling water control valve 4 is set to be fully open, most of the cooling water flows through the bypass passage 51 and the first jacket 22a.

[0112] The combustion chamber 16 can be quickly heated by the circulating cooling water. Because the cooling water circulates, the combustion chamber 16 and its surroundings can be heated evenly. The engine 10 quickly reaches a temperature state suitable for combustion, improving fuel efficiency.

[0113] At this time, the remainder of the coolant discharged by the water pump 3 circulates through the second circuit 30 and the third circuit 40 (the same applies in the case of "complete warm-up"). Also, the temperature of the coolant in the "semi-warm-up" state is lower than the opening temperature of the thermostat valve 28. Therefore, the thermostat valve 28 is in a fully closed state. No part of the coolant flows into the radiator flow path 53 from the bypass flow path 51.

[0114] At the time of "complete warm-up", the engine 10 has reached a temperature state suitable for combustion. After the engine 10 has been completely warmed up, the engine 10 switches the combustion mode depending on the load and the rotation speed, as described above. The engine system 1 controls the circulation device 91 so that the wall temperature of the combustion chamber 16 becomes a temperature suitable for the combustion mode. At the time of "complete warm-up", the engine system 1 switches between a state 82 shown in the center of FIG. 6 and a state 83 shown on the right side of FIG. 6 depending on the operating state of the engine 10. As described above, the state 82 is a state in which the bypass passage 51 is opened and the radiator passage 53 is closed. However, at the time of "complete warm-up", the temperature of the cooling water is rising, and therefore, as described later, the thermostat valve 28 may open and the cooling water may flow through the radiator passage 53. The state 83 is a state in which the cooling water is circulated using the entire first circuit 50 by opening both the bypass passage 51 and the radiator passage 53.

[0115] More specifically, in the case of "complete warm-up", which is a state 82 shown in the center, the rotary valve element 61 of the coolant control valve 4 is set to a rotational position where the first port 63 communicates with the third port 65 and the second port 64 does not communicate with the third port 65. Then, the flow rate of the coolant is adjusted in the first port 63 (bypass flow passage 51) according to the load of the engine 10.

[0116] In the state 83 shown on the right in the case of "complete warm-up", the coolant flows through both the bypass passage 51 and the radiator passage 53. In this case, in the coolant control valve 4, the rotary valve element 61 is set to a rotational position where both the first port 63 and the second port 64 communicate with the third port 65. Then, the flow rate of the coolant is adjusted in both the first port 63 (bypass passage 51) and the second port 64 (radiator passage 53) according to the load of the engine 10.

[0117] (How to drain the cooling water when the engine is fully warmed up) A specific example of how the cooling water flows during complete warm-up is shown in Fig. 7. In Fig. 7, changes in main parameters according to the magnitude of the load on the engine 10 are shown in each of the charts (A) to (D).

[0118] Graph (A) shows a change G1 in the flow rate of the coolant passing through the coolant control valve 4, and a change G2 in the flow rate of the coolant passing through the radiator flow path 53. Graph (B) shows a breakdown of the changes in the flow rate of the coolant flowing through the first circuit 50, that is, a change G3 in the flow rate of the coolant flowing from the coolant control valve 4 to the bypass flow path 51, a change G4 in the flow rate of the coolant flowing through the communication flow path 52, and a change G5 in the flow rate of the coolant flowing from the coolant control valve 4 to the radiator flow path 53.

[0119] (C) shows a change G6 in the temperature of the cooling water flowing through the first jacket 22a, and a change G7 in the temperature of the cooling water flowing into the water pump 3. In other words, the changes in the measured values ​​of the second water temperature sensor SN2 and the first water temperature sensor SN1 are shown. (D) shows a change G8 in the wall temperature of the combustion chamber 16.

[0120] The load region of the engine 10 is divided into three regions, which are a region below the first load L1, a region equal to or greater than the second load L2, and a region equal to or greater than the first load L1 and less than the second load L2, in relation to the control of the cooling water. Each chart in FIG. 7 corresponds to a case where the engine 10 is at a low or medium speed. The region below the first load L1 generally corresponds to a region where the engine 10 performs HCCI combustion or MPCI combustion. The region equal to or greater than the second load L2 generally corresponds to a region where the engine 10 performs SI combustion. The region between the first load L1 and the second load L2 generally corresponds to a region where the engine 10 performs SPCCI combustion. The first load L1 and the second load may or may not coincide with the load at which the combustion mode is switched.

[0121] In this engine system 1, the flow rate of the cooling water is controlled in a region below the first load L1, and the temperature of the cooling water is controlled in a region between the first load L1 and the second load L2. As a result, the wall temperature of the combustion chamber 16 is maintained at a specific constant temperature in the low load region and the medium load region of the engine 10 (see G8).

[0122] That is, in order to realize compression ignition combustion without forced ignition such as HCCI combustion or MPCI combustion, it is necessary to control the temperature in the combustion chamber 16 (in-cylinder temperature) at a higher temperature than that in SI combustion and with high precision. On the other hand, SPCCI combustion is a combustion with forced ignition, although a part of the mixture is burned by compression ignition, and the temperature in the combustion chamber 16 is allowed to be lower than that in the case of HCCI combustion or MPCI combustion. Conversely, if the temperature in the combustion chamber 16 is too high, the mixture may self-ignite before forced ignition, or the proportion of self-ignition combustion may become too large in SPCCI combustion, which is a combination of flame propagation combustion and self-ignition combustion. In other words, if the temperature in the combustion chamber 16 is too high, stable SPCCI combustion cannot be realized.

[0123] Therefore, it is ideal to increase or decrease the wall temperature of the combustion chamber 16 in response to the switching of the combustion mode. However, since the heat capacity of the wall of the combustion chamber 16 is large, it is difficult to change the wall temperature of the combustion chamber 16 with good responsiveness in response to the switching of the combustion mode or the change in the load. Therefore, in this engine system 1, the wall temperature of the combustion chamber 16 is maintained at a specific constant temperature in the low to medium load range. This specific temperature is an intermediate temperature between the optimum temperature for HCCI combustion or MPCI combustion and the optimum temperature for SPCCI combustion, and is a temperature that is acceptable for the execution of HCCI combustion or MPCI combustion, and is also an acceptable temperature for the execution of SPCCI combustion. By maintaining the wall temperature of the combustion chamber 16 at a constant temperature, the wall temperature of the combustion chamber 16 becomes an appropriate temperature even if the combustion mode is switched or the load is changed.

[0124] However, when the load of the engine 10 is low, the heat of combustion generally decreases, whereas when the load of the engine 10 is high, the heat of combustion generally increases. In order to maintain a constant wall temperature of the combustion chamber 16 regardless of the load of the engine 10, it is necessary to adjust the amount of heat exchange by the cooling water with high responsiveness to the generated heat of combustion.

[0125] In order to adjust the amount of heat exchange, it is conceivable to adjust, for example, the temperature of the cooling water in accordance with the load of the engine 10. However, since the heat capacity of the cooling water is large, it takes a long time to raise or lower the temperature of the cooling water. It is difficult to adjust the temperature of the cooling water with high response to changes in the load of the engine 10.

[0126] Therefore, this engine system 1 maintains the temperature of the coolant at a constant predetermined temperature, and uses the coolant control valve 4 to adjust the flow rate of the coolant flowing through the first port 63 and the first jacket 22a in accordance with the load of the engine 10. Since the flow rate can be adjusted with high responsiveness, the heat transfer coefficient of the coolant can be adjusted with high responsiveness to the generated combustion heat, and as a result, the wall temperature of the combustion chamber 16 can be maintained constant.

[0127] (Area below the first load L1) As shown in FIG. 7, in the region below the first load L1, the coolant control valve 4 does not allow the coolant to flow through the radiator passage 53, but adjusts the flow rate of the coolant flowing through the bypass passage 51 (see G3, G5).

[0128] Since the radiator flow passage 53 is closed, the temperature of the cooling water is determined by the valve opening temperature of the thermostatic valve 28. The valve opening temperature of the thermostatic valve 28 is set to a relatively high temperature. The temperature of the cooling water flowing through the first jacket 22a is constant at the first target temperature t21 regardless of the load (see G6). The first target temperature t21 is a temperature close to the temperature related to the reliability limit of the engine 10. By setting the temperature of the cooling water to a relatively high temperature, it is possible to maintain the wall temperature of the combustion chamber 16 at a relatively high temperature (i.e., the target temperature tw) in a region below the first load L1. A high wall temperature of the combustion chamber 16 is advantageous for stabilizing compression ignition combustion without forced ignition, such as HCCI combustion or MPCI combustion. In the illustrated example, in a region below the first load L1, the temperature of the cooling water flowing into the engine 10 gradually increases as the load of the engine 10 increases (see G7).

[0129] In the region below the first load L1, when the load of the engine 10 is low, the flow rate of the cooling water flowing through the bypass passage 51 is small, and when the load of the engine 10 is high, the flow rate of the cooling water flowing through the bypass passage 51 is increased, by adjusting the flow rate by the cooling water control valve 4.

[0130] At this time, in the coolant control valve 4, the actuator 62 is controlled so that the rotary valve element 61 is located at a rotational position where the third port 65 is not in communication with the second port 64 and is in communication with the first port 63. Then, the degree of opening between the third port 65 and the first port 63 is adjusted to be large or small according to the load of the engine 10.

[0131] In the region below the first load L1, the flow rate of the cooling water flowing through the communication passage 52 when the thermostat valve 28 opens changes in response to the change in the flow rate of the cooling water flowing through the bypass passage 51 (see G4).

[0132] In the illustrated example, the load of the engine 10 and the flow rate of the cooling water have a linear relationship, but the relationship is not limited to a linear relationship.

[0133] The flow rate of the cooling water flowing through the first jacket 22a corresponds to the flow rate of the cooling water flowing through the bypass passage 51. Therefore, when the load of the engine 10 is low, the flow rate of the cooling water flowing through the first jacket 22a is low, and when the load of the engine 10 is high, the flow rate of the cooling water flowing through the first jacket 22a is high. In the example of FIG. 7, when the load of the engine 10 is the first load L1, the flow rate of the cooling water flowing through the first jacket 22a becomes the maximum flow rate (see G1). However, when the load of the engine 10 is the first load L1, the flow rate of the cooling water flowing through the first jacket 22a may be set to a flow rate lower than the maximum flow rate.

[0134] When the flow rate of the cooling water flowing through the first jacket 22a is low, the heat transfer coefficient with the combustion chamber 16 decreases. Therefore, even if the heat of combustion decreases, the wall temperature of the combustion chamber 16 can be adjusted to be high. When the flow rate of the cooling water flowing through the first jacket 22a is high, the heat transfer coefficient with the combustion chamber 16 increases. Therefore, even if the heat of combustion increases, the wall temperature of the combustion chamber 16 can be adjusted to be low.

[0135] In this way, while maintaining the temperature of the cooling water constant using the thermostat valve 28 (see G6), the flow rate of the cooling water flowing through the first jacket 22a is increased or decreased using the cooling water control valve 4 in a highly responsive manner depending on the load on the engine 10 (see G1, G3), thereby making it possible to maintain the wall temperature of the combustion chamber 16 constant at the target temperature tw (see G8).

[0136] (Area between first load L1 and second load L2) The flow rate of the cooling water flowing through the cooling water control valve 4, i.e., the flow rate of the cooling water flowing through the first circuit 50, reaches its upper limit at the first load L1 (see G1). That is, flow rate control cannot be performed at loads equal to or greater than the first load L1. Therefore, in the region between the first load L1 and the second load L2, the temperature of the cooling water is controlled. As the load of the engine 10 increases, the cooling water flowing through the bypass flow passage 51 is gradually diverted to the radiator flow passage 53 for cooling, thereby maintaining the wall temperature of the combustion chamber 16 at the target temperature tw.

[0137] Specifically, while the flow rate of the cooling water flowing through the first circuit 50 is kept at a maximum by the cooling water control valve 4, as the load of the engine 10 increases, the flow rate of the cooling water flowing through the bypass flow path 51 is gradually decreased while the flow rate of the cooling water flowing through the radiator flow path 53 is gradually increased (see G1, G2, G3, and G5). In a region of the first load L1 or more and less than the second load L2, the cooling water control valve 4 adjusts the flow rate of the cooling water flowing through the radiator flow path 53 to adjust the temperature of the cooling water flowing through the first jacket 22a. Note that when the load of the engine 10 is the first load L1 or more, the flow rate of the cooling water flowing through the radiator flow path 53 exceeds the flow rate of the cooling water flowing through the bypass flow path 51. The load of the engine 10 at which the flow rates are reversed varies depending on the operating environment of the engine 10 (for example, the outside temperature, the amount of wind during running, etc.).

[0138] In the coolant control valve 4, the actuator 62 is controlled so that the rotary valve element 61 is positioned at a rotational position where the third port 65 is in communication with both the first port 63 and the second port 64. Then, the degree of opening between the third port 65 and each of the first port 63 and the second port 64 is adjusted to be large or small according to the load of the engine 10.

[0139] As a result, the temperature of the cooling water flowing through the first jacket 22a and the cooling water flowing into the engine 10 is lower as the load of the engine 10 is higher (see G6 and G7). When the load of the engine 10 is higher and the heat of combustion increases, the amount of cooling by the cooling water flowing through the first jacket 22a can be maintained because the temperature of the cooling water is low even if the flow rate of the cooling water flowing through the first jacket 22a is constant. In addition, the flow rate of the cooling water flowing through the first circuit 50 is the maximum flow rate, which is advantageous for cooling the combustion chamber 16. As a result, even in the region of the first load L1 or more and less than the second load L2, the wall temperature of the combustion chamber 16 can be maintained at the target temperature tw (see G8).

[0140] In order to suppress an excessive temperature rise in the combustion chamber 16, in the cooling system 2, a second target temperature t22 (e.g., 88°C) lower than the first target temperature t21 is set as the target temperature of the cooling water flowing through the first jacket 22a. The temperature control is performed until the temperature of the cooling water flowing through the first jacket 22a reaches the second target temperature t22.

[0141] 7, when the temperature of the cooling water reaches the second target temperature t22, the flow rate of the cooling water flowing through the radiator passage 53 is less than the maximum flow rate. If the flow rate of the cooling water flowing through the radiator passage 53 is further increased, the temperature of the cooling water can be further reduced. In other words, even if the load of the engine 10 exceeds L2, it is possible to maintain the wall temperature of the combustion chamber 16 at the target wall temperature tw.

[0142] In this way, the engine system 1 can maintain the wall temperature of the combustion chamber 16 constant over a wide range of loads, from low to medium, of the engine 10, by combining flow rate control and temperature control. Even if the combustion type switches between HCCI combustion, MPCI combustion, and SPCCI combustion in response to changes in the load of the engine 10, each combustion is performed stably because the wall temperature of the combustion chamber 16 is maintained at an appropriate temperature.

[0143] The coolant control valve 4 having the rotary valve body 61 can selectively close the bypass passage 51 and / or the radiator passage 53, and can adjust the flow rate of the bypass passage 51 and the flow rate of the radiator passage 53. The engine system 1 equipped with the coolant control valve 4 can achieve the above-mentioned flow rate adjustment of the water jacket 20 with a simple configuration.

[0144] In addition, in the region of the first load L1 or more and less than the second load L2, the cooling water flowing into the radiator flow passage 53 through the communication flow passage 52 gradually decreases and stops flowing as the load of the engine 10 increases (see G4). In detail, the temperature of the cooling water flowing into the bypass flow passage 51 from the cooling water control valve 4 gradually decreases from the first target temperature t21. Accordingly, the temperature of the cooling water flowing through the thermostat valve 28 also decreases. Therefore, in the region of the first load L1 or more and less than the second load L2, the thermostat valve 28 gradually closes and becomes fully closed. As a result, the cooling water flowing into the radiator flow passage 53 through the communication flow passage 52 gradually decreases and stops flowing.

[0145] 7, there is a proportional relationship between the decrease in the flow rate of the cooling water flowing through the bypass passage 51 and the increase in the flow rate of the cooling water flowing through the radiator passage 53, but this does not have to be the proportional relationship. In the region between the first load L1 and the second load L2, the flow rate of the cooling water flowing through the cooling water control valve 4 may be equal to or lower than the upper limit.

[0146] (Area above the second load L2) In the region of the second load L2 or more, the coolant control valve 4 adjusts so that the temperature of the coolant flowing through the first jacket 22a is maintained at the second target temperature t22. Specifically, the actuator 62 is controlled to adjust so that the opening between the third port 65 and the second port 64 is increased and the opening between the third port 65 and the first port 63 is decreased as the load of the engine 10 increases. As a result, the amount of coolant flowing through the radiator passage 53 gradually increases, and the amount of coolant flowing through the bypass passage 51 gradually decreases (see G3 and G5). This allows the temperature of the coolant flowing through the first jacket 22a to be maintained at the second target temperature t22 (see G6).

[0147] In the region where SI combustion is performed, abnormal combustion such as knocking can be suppressed by keeping the coolant temperature relatively low.

[0148] In the region between the first load L1 and the second load L2 described above, in order to keep the wall temperature of the combustion chamber 16 constant, the temperature of the cooling water flowing through the first jacket 22a is actively lowered as the load of the engine 10 increases, so that the degree of change in the flow rate of the cooling water flowing from the cooling water control valve 4 to the bypass flow path 51 and the flow rate of the cooling water flowing from the cooling water control valve 4 to the radiator flow path 53 in response to an increase in the load of the engine 10 is relatively increased. In other words, the slopes of G3 and G5 are large.

[0149] On the other hand, in the region equal to or greater than the second load L2, the temperature of the coolant is maintained at the second target temperature t22, so that the degree of change in the flow rate of the coolant flowing from the coolant control valve 4 to the bypass flow path 51 and the flow rate of the coolant flowing from the coolant control valve 4 to the radiator flow path 53 in response to an increase in the load of the engine 10 is relatively small. In other words, the slopes of G3 and G5 are small, and the slopes of G3 and G5 change at the boundary of the second load L2.

[0150] Incidentally, even in the region of the second load L2 or more, the proportional relationship between the decrease in the flow rate of the cooling water flowing through the bypass passage 51 and the increase in the flow rate of the cooling water flowing through the radiator passage 53 is not necessarily required. In the region of the second load L2 or more, the flow rate of the cooling water flowing through the cooling water control valve 4 may be equal to or lower than the upper limit.

[0151] In the region equal to or greater than the second load L2, the flow rate of the cooling water flowing through the first jacket 22a is at a maximum, and the temperature of the cooling water is maintained at the second target temperature t22. As the load of the engine 10 increases, the amount of heat generated in the combustion chamber 16 increases, and therefore the wall temperature of the combustion chamber 16 gradually rises as the load of the engine 10 increases (see G8).

[0152] In the region equal to or greater than the second load L2, the temperature of the coolant is maintained at the second target temperature t22, so the thermostat valve 28 is fully closed. No coolant flows through the communication passage 52. The bypass passage 51 and the radiator passage 53 form passages independent of each other.

[0153] Next, the control executed by the ECU 100 regarding the cooling of the engine 10 will be described with reference to FIGS.

[0154] 8 is a flow chart relating to switching between the low temperature state, the semi-warmed-up state, and the fully warmed-up state of the engine 10. First, in step S81 after starting, the ECU 100 acquires signal values ​​output by the various sensors SN1 to SN5. In the following step S82, the ECU 100 determines whether the coolant temperature t is equal to or higher than the second switching temperature t12 based on the signal of the second water temperature sensor SN2. If the coolant temperature t is equal to or higher than the second switching temperature t12, the process proceeds from step S82 to step S83. In step S83, the ECU 100 executes the fully warmed-up control. Details of the fully warmed-up control will be described with reference to FIG. 9.

[0155] If the coolant temperature is less than the second switching temperature t12, the process proceeds from step S82 to step S84. In step S84, the ECU 100 determines whether the coolant temperature t is equal to or higher than the first switching temperature t11. If the coolant temperature t is equal to or higher than the first switching temperature t11, the process proceeds from step S84 to step S85. In step S85, the ECU 100 executes semi-warm-up control. As described above, the ECU 100 opens the bypass passage 51 and closes the radiator passage 53 through the coolant control valve 4.

[0156] If the coolant temperature t is lower than the first switching temperature t11, the process proceeds from step S84 to step S86. In step S86, the ECU 100 executes low-temperature control. As described above, the ECU 100 closes the bypass passage 51 and closes the radiator passage 53 through the coolant control valve 4.

[0157] 9 shows a flow of the complete warm-up control in step S83. In step S91 after starting, the ECU 100 calculates a target load for the engine 10 based on the signal values ​​output by the sensors SN1 to SN5. In the following step S92, it is determined whether the target load L is less than the first load L1. If the target load L is less than the first load L1, the process proceeds from step S92 to step S93. In step S93, the ECU 100 performs flow control. That is, the ECU 100 closes the radiator flow path 53 through the coolant control valve 4 and adjusts the flow rate of the bypass flow path 51 according to the load of the engine 10.

[0158] If the target load L is equal to or greater than the first load L1, the process proceeds from step S92 to step S94. In step S94, the ECU 100 determines whether the target load L is less than the second load L2. If the target load L is less than the second load L2, the process proceeds from step S94 to step S95. In step S95, the ECU 100 performs temperature control. That is, the ECU 100 adjusts the flow rates of the radiator passage 53 and the bypass passage 51 according to the load of the engine 10 through the coolant control valve 4 so that the wall temperature of the combustion chamber 16 is constant.

[0159] If the target load L is equal to or greater than the second load L2, the process proceeds from step S94 to step S96. In step S96, the ECU 100 adjusts the flow rates of the radiator passage 53 and the bypass passage 51 according to the load of the engine 10 via the coolant control valve 4 so that the temperature of the coolant is constant.

[0160] (Modification of the Circulation Device) 10 shows a circulation device 92 according to a modified example. This circulation device 92 differs from the circulation device 91 in FIG. 4 in the position of the thermostat valve 28.

[0161] Specifically, the thermostatic valve 28 is attached to the outflow end 10b of the engine 10, not to the bypass passage 51. The downstream end of the first jacket 22a provided in the cylinder head 12 branches into two. The cooling water control valve 4 and the thermostatic valve 28 are each connected to the first jacket 22a.

[0162] The thermostatic valve 28 is also connected to a radiator passage 53 via a communication passage 52. More specifically, the communication passage 52 is connected to the radiator passage 53 upstream of the radiator 27.

[0163] Incidentally, the circulation device 92 does not have a communication passage that connects the bypass passage 51 and the radiator passage 53 in the circulation device 91 of FIG.

[0164] The way in which the coolant flows in the circulation device 92 is the same as in the circulation device 91 of Fig. 4. That is, when the temperature t of the coolant is "low temperature" below the first switching temperature t11, the coolant does not flow through either the bypass flow path 51 or the radiator flow path 53 (the flow rate of both is zero). At this time, in the coolant control valve 4, the rotary valve element 61 is set to a rotation position where neither the first port 63 nor the second port 64 communicates with the third port 65. Also, the thermostat valve 28 is closed. Therefore, the coolant does not circulate in the first circuit 50.

[0165] In the "semi-warm-up" state where the coolant temperature t is equal to or higher than the first switching temperature t11 and lower than the second switching temperature t12, the coolant flows through the bypass passage 51 but not through the radiator passage 53 (the flow rate through the radiator passage 53 is zero). At this time, in the coolant control valve 4, the rotary valve element 61 is set to a rotation position where only the first port 63 communicates with the third port 65. The opening of the first water passage opening 61a is, for example, fully open. Also, since the temperature of the coolant is low, the thermostat valve 28 is closed. In the first circuit 50, the coolant circulates only through the bypass passage 51.

[0166] During "complete warm-up" when the cooling water temperature t is equal to or higher than the second switching temperature t12, the circulation device 92 is controlled depending on the level of the load.

[0167] Specifically, when the operating state of the engine 10 is in a region below the first load L1, flow rate control is executed. The temperature of the coolant is kept constant by the thermostat valve 28. The coolant control valve 4 opens the bypass passage 51 and closes the radiator passage 53. However, when the thermostat valve 28 is opened, the coolant may pass through the radiator 27. The coolant control valve 4 adjusts the flow rate of the coolant flowing through the bypass passage 51 depending on the load of the engine 10. Thereby, the wall temperature of the combustion chamber 16 is maintained at the target temperature tw.

[0168] When the operating state of the engine 10 is in a region of the first load L1 or more and less than the second load L2, temperature control is executed. The coolant control valve 4 opens both the bypass passage 51 and the radiator passage 53. More specifically, as the load of the engine 10 increases, the coolant control valve 4 reduces the flow rate of the coolant flowing through the bypass passage 51 and increases the flow rate of the coolant flowing through the radiator passage 53. This maintains the wall temperature of the combustion chamber 16 at the target temperature tw.

[0169] When the operating state of the engine 10 is in a region equal to or higher than the second load L2, the coolant control valve 4 adjusts the flow rates of the coolant flowing through the bypass passage 51 and the radiator passage 53 so that the coolant temperature t is constant at the second target temperature t22. More specifically, as the load of the engine 10 increases, the coolant control valve 4 reduces the flow rate of the coolant flowing through the bypass passage 51 and increases the flow rate of the coolant flowing through the radiator passage 53. The thermostat valve 28 is closed.

[0170] The engine system 1 equipped with the circulation device 92 also performs flow control in the region less than the first load L1, so that the flow rate of the cooling water flowing through the first jacket 22a can be changed with high response in response to changes in the load of the engine 10, and the wall temperature of the combustion chamber 16 can be kept constant.

[0171] Furthermore, by performing temperature control in the region equal to or greater than the first load L1 and less than the second load L2, the wall temperature of the combustion chamber 16 can be maintained at the target temperature tw, so that even if the load of the engine 10 changes between the first load L1 and the second load L2, the wall temperature of the combustion chamber 16 does not change. HCCI combustion and MPCI combustion without forced ignition can be stably performed, and SPCCI combustion with forced ignition can also be stably performed.

[0172] In the circulation device 92, the thermostat valve 28 is not provided downstream of the cooling water control valve 4. The communication flow path 52 is a flow path that bypasses the cooling water control valve 4. Therefore, even if the cooling water control valve 4 fails due to sticking or the like, if the temperature of the cooling water reaches the opening temperature of the thermostat valve 28, the thermostat valve 28 opens, and the cooling water can be cooled by the radiator 27. The circulation device 92 is advantageous in improving the reliability of the engine system 1 because it can prevent the temperature of the cooling water from becoming excessively high.

[0173] (Other embodiments) In addition, the position of the coolant control valve 4 may be changed in the circulation device 91 of Fig. 4. Specifically, the coolant control valve 4 may be provided at a location where the bypass flow path 51 and the radiator flow path 53 join together (a location surrounded by a dashed line in Fig. 4). In this configuration, the upstream end of the bypass flow path 51 and the upstream end of the radiator flow path 53 are connected to the first jacket 22a independently of each other. In addition, the communication flow path 52 communicates the bypass flow path 51 with the radiator flow path 53 downstream of the radiator 27, and the thermostat valve 28 may be provided to open and close the communication flow path 52.

[0174] Similarly, the position of the coolant control valve 4 may be changed in the circulation device 92 of Fig. 10. Specifically, the coolant control valve 4 may be provided at a location where the bypass flow path 51 and the radiator flow path 53 join together (a location surrounded by a dashed line in Fig. 10). In this configuration, the upstream end of the bypass flow path 51 and the upstream end of the radiator flow path 53 are connected to the first jacket 22a independently of each other. Also, the communication flow path 52 may be provided to communicate the downstream of the radiator 27 and the upstream of the water pump 3 in the radiator flow path 53 so as to bypass the coolant control valve 4, and the thermostat valve 28 may be provided to open and close the communication flow path 52.

[0175] Furthermore, the flow rate adjustment device is not limited to being configured by the cooling water control valve 4 having the rotary valve body 61. The flow rate adjustment device may be configured by a first flow rate adjustment valve that adjusts the flow rate of the cooling water flowing through the bypass flow path 51, and a second flow rate adjustment valve that adjusts the flow rate of the cooling water flowing through the radiator flow path 53 and is independent of the first flow rate adjustment valve.

[0176] 3 shows an example of control of the engine system 1. The engine system 1 does not need to switch the combustion mode. Even if the engine system 1 switches the combustion mode, the switching is not limited to the example shown in FIG. [Explanation of symbols]

[0177] 1 Engine System 10 Engine 16 Combustion chamber 100 ECU (Controller) 22a 1st jacket (water jacket) 27 Radiator (heat exchanger) 28 Thermostatic valve 4. Cooling water control valve (flow regulator) 51 Bypass flow path 52 Connecting Channel 53 Radiator passage 91 Circulation device 92 Circulation device

Claims

1. An engine having a water jacket disposed around a combustion chamber; a circulation device attached to the engine and configured to circulate cooling water through the water jacket; a controller that controls the circulation device in accordance with an operating state of the engine; The circulation device includes: a radiator flow path including a heat exchanger; a bypass flow path that bypasses the heat exchanger; a flow rate adjusting device that adjusts a flow rate of the cooling water flowing through the water jacket by adjusting a flow rate of the cooling water flowing through each of the radiator flow path and the bypass flow path; a thermostat valve connected to the radiator flow path and opening to allow the coolant to pass through the heat exchanger; The controller is electrically connected to the flow control device and When a load of the engine is lower than a first load, the flow rate control device is controlled to close the radiator flow path and adjust a flow rate of the cooling water flowing through the bypass flow path to adjust a flow rate of the cooling water flowing through the water jacket in accordance with the load; and When the load is equal to or greater than the first load, the flow rate control device is controlled so that the cooling water flows through each of the radiator flow path and the bypass flow path. Engine system.

2. 2. The engine system according to claim 1, When the load is lower than the first load, the controller increases a flow rate of the cooling water flowing through the water jacket when the load is high, more than when the load is low. Engine system.

3. 3. The engine system according to claim 1, When the load is equal to or greater than the first load, the controller adjusts a flow rate of the cooling water flowing through the bypass flow path and a flow rate of the cooling water flowing through the radiator flow path to adjust a temperature of the cooling water flowing through the water jacket in accordance with the load. Engine system.

4. 4. The engine system according to claim 3, When the load is equal to or higher than the first load, the controller reduces a flow rate of the cooling water flowing through the bypass flow path and increases a flow rate of the cooling water flowing through the radiator flow path when the load is high, compared to when the load is low. Engine system.

5. In the engine system according to any one of claims 1 to 4, The controller sets a flow rate of the cooling water flowing through the water jacket to a maximum flow rate when the load is equal to or greater than the first load. Engine system.

6. In the engine system according to any one of claims 1 to 5, The controller maintains a wall temperature of the combustion chamber at a constant temperature when the load is lower than the first load and when the load is equal to or higher than the first load. Engine system.

7. 7. The engine system according to claim 6, The controller reduces a temperature of the cooling water flowing through the water jacket below a valve opening temperature of the thermostat valve when the load is equal to or higher than the first load. Engine system.

8. 5. The engine system according to claim 4, the controller increases a flow rate of the cooling water flowing through the radiator flow passage so that a temperature of the cooling water flowing through the water jacket decreases in response to an increase in the load when the load is equal to or greater than the first load and lower than a second load, and increases a flow rate of the cooling water flowing through the radiator flow passage so that a temperature of the cooling water flowing through the water jacket remains constant in response to an increase in the load when the load is equal to or greater than the second load. Engine system.

9. In the engine system according to any one of claims 1 to 8, the engine has an ignition device which forcibly ignites an air-fuel mixture, and when the load is lower than the first load, the air-fuel mixture in the combustion chamber is burned without forced ignition by the ignition device, and when the load is equal to or higher than the first load, the air-fuel mixture in the combustion chamber is burned by forced ignition by the ignition device. Engine system.

10. In the engine system according to any one of claims 1 to 9, The flow rate control device is installed at a location where the bypass flow path and the radiator flow path branch off or at a location where the bypass flow path and the radiator flow path join together, The circulation device further includes a communication passage that communicates the bypass passage and the radiator passage, The thermostat valve opens and closes the communication passage. Engine system.

11. In the engine system according to any one of claims 1 to 9, The flow rate control device is installed at a location where the bypass flow path and the radiator flow path branch off or at a location where the bypass flow path and the radiator flow path join together, The circulation device further includes a communication passage that bypasses the flow rate adjustment device and connects the water jacket and the radiator passage, The thermostat valve opens and closes the communication passage. Engine system.

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