JP5541371B2 - Engine cooling system - Google Patents

Description

  The present invention relates to an engine cooling apparatus.

  Engines are generally cooled with cooling water. It is also known that the engine head has a high thermal load on the cylinder. Patent Document 1 discloses a cooling device for a multi-cylinder engine that improves the cooling performance of the cylinder head while preventing excessive cooling of the cylinder block. Patent Document 2 discloses a cooling device for an internal combustion engine that actively cools the wall surface on the exhaust port side of the combustion chamber to improve the cooling efficiency of the internal combustion engine.

Japanese Patent Application Laid-Open No. 08-177483 JP 2009-216029 A

  FIG. 10 is a diagram showing a breakdown of the heat balance of the engine. In FIG. 10, the breakdown of the general heat balance of the spark ignition type internal combustion engine is shown for the full load case and the partial load case, respectively. A spark ignition type internal combustion engine generates a lot of heat that is not used for net work such as exhaust loss and cooling loss. The reduction of the cooling loss, which accounts for a large proportion of the total energy loss, is a very important factor for improving the thermal efficiency (fuel consumption). However, it is not always easy to reduce cooling loss and effectively use heat, which hinders improvement in thermal efficiency.

  The reason why it is difficult to reduce the cooling loss is that, for example, a general engine is not configured to locally change the state of heat transfer. That is, in a general engine, it is difficult to cool a part that needs to be cooled to a necessary degree because of the configuration. Specifically, when changing the state of heat transfer of the engine, generally, the flow rate of the cooling water is changed according to the engine speed by a mechanical water pump driven by the output of the engine. . However, in the water pump that adjusts the flow rate of the cooling water as a whole, even if a variable water pump that makes the flow rate variable is used, the heat transfer state can be locally changed according to the engine operating state. I can't do it.

  FIG. 11 is a diagram showing the inner wall temperature and heat transmittance of the cylinder. In FIG. 11, these are shown respectively for the case of the normal configuration and the case of increasing the heat insulation. As a case of a normal configuration, a case of a general engine provided with one cooling water circulation path for circulating cooling water from the lower part of the cylinder block toward the cylinder head against gravity is shown. Moreover, as a case where heat insulation is improved, the case where the material is changed as the wall thickness of the cylinder is increased and the case where air insulation with higher heat insulation is performed are shown.

  Here, in reducing the cooling loss, for example, it is conceivable to improve the heat insulation of the engine. In this case, a significant reduction in cooling loss can be expected as shown in FIG. However, in this case, by increasing the heat insulation of the engine, the temperature of the inner wall of the combustion chamber increases at the same time. In this case, knocking is induced when the temperature of the air-fuel mixture rises accordingly.

  In view of the above problems, an object of the present invention is to provide an engine cooling device that can achieve both reduction in cooling loss and knock performance.

  The present invention includes a cylinder block and a cylinder head of an engine provided with a first cooling medium passage and a second cooling medium passage for circulating a cooling medium, and the first cooling medium passage includes the cooling medium. After the cylinder block is circulated to the exhaust side portion, the cylinder head is circulated to the exhaust side portion including a predetermined area around the spark plug provided in the cylinder head, and the second The cooling medium passage is incorporated in a cooling medium circulation path different from the cooling medium circulation path in which the first cooling medium passage is incorporated, and the cooling medium is circulated through the intake side portion of the cylinder block. The engine cooling device is circulated to a portion on the intake side of the cylinder head.

  In the present invention, when the cooling medium is circulated through the engine, the cooling medium is circulated through the first cooling medium passage and the cooling medium is circulated through the second cooling medium passage. It is preferable that the configuration further includes cooling medium control means for reducing the flow rate of the cooling medium to be circulated through the second cooling medium passage when the load is low to medium load than when the load is high.

  Further, the present invention is an engine in which exhaust gas recirculation is performed, a cooler capable of cooling exhaust gas recirculated to the engine by heat exchange with the circulating cooling medium, and the first cooling medium passage It is preferable that the configuration further includes a first branching portion that divides the cooling medium flowing through the flow passage and flows through the cooler.

  Further, the present invention provides a heater that can heat air by heat exchange with the circulating cooling medium, and a second that distributes the cooling medium flowing through the first cooling medium passage to the heater. It is preferable that it is the structure further equipped with these branch parts.

  According to the present invention, both reduction in cooling loss and knock performance can be achieved.

1 is a schematic configuration diagram of an engine cooling device according to Embodiment 1. FIG. It is a figure which shows a water jacket. It is a figure which shows the cooling area | region of a water jacket. It is an enlarged view of the cooling area | region of a water jacket. It is a schematic block diagram of ECU. It is a figure which shows operation | movement of ECU with a flowchart. It is a figure which shows the heat transfer rate and surface area ratio of a combustion chamber according to a crank angle. It is a schematic block diagram of the engine cooling device of Example 2. FIG. 6 is a schematic configuration diagram of an engine cooling device according to a third embodiment. It is a figure which shows the breakdown of the heat balance of an engine. It is a figure which shows the inner-wall temperature and heat transmittance of a cylinder.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an engine cooling device (hereinafter referred to as a cooling device) 1A. The cooling device 1A is mounted on a vehicle (not shown). The cooling device 1 </ b> A includes a water pump (hereinafter referred to as W / P) 11, a radiator 12, a thermostat 13, a flow control valve 14, and an engine 50.

  W / P11 is a cooling medium pumping means for pumping cooling water as a cooling medium. Specifically, W / P11 is a variable W / P that makes the flow rate of the cooling water pumped variable. W / P11 may be a mechanical W / P driven by the output of the engine 50. Cooling water pumped by the W / P 11 is supplied to the engine 50. The engine 50 is provided with a first water jacket (hereinafter referred to as W / J) 501 and a second W / J 502. Specifically, the cooling water pumped by the W / P 11 is supplied to the W / J 501 and 502.

  FIG. 2 is a diagram showing W / J 501 and 502. FIG. 3 is a view showing cooling regions R1 and R2 of W / J 501 and 502. FIG. FIG. 4 is an enlarged view of the cooling regions R1 and R2. FIG. 2 is a perspective view of the engine 50 and shows a schematic structure of the W / J 501 and 502. FIG. 3 is a top view of the engine 50 and shows the cooling regions R1 and R2. FIG. 4 is an enlarged view of the cooling regions R1 and R2 per cylinder of the engine 50 among the cooling regions R1 and R2 shown in FIG. The cooling region R1 indicates the cooling region of the first W / J 501 in the cylinder head 52, and the cooling region R2 indicates the cooling region of the second W / J 502 in the cylinder head 52.

  The engine 50 includes a cylinder block 51, a cylinder head 52, a gasket 53, and a spark plug 54. A cylinder 51 a is formed in the cylinder block 51. A cylinder head 52 is provided on the cylinder block 51 via a gasket 53. The gasket 53 has high heat insulating properties. The cylinder head 52 is provided with a spark plug 54 for each cylinder 51a. The cylinder block 51 and the cylinder head 52 form a combustion chamber together with a piston (not shown).

  The first W / J 501 circulates cooling water to the exhaust side portion of the cylinder block 51, and includes a predetermined area around the spark plug 54 of the cylinder head 52 and includes a cooling medium in the exhaust side portion. Circulate. The predetermined area is an area in the cylinder head 52 where the portion around the spark plug 54 can be cooled. For this reason, a portion of the cylinder head 52 around the spark plug 54 is included in the cooling region R1.

  The second W / J 502 circulates cooling water in the intake side portion of the cylinder block 51 and circulates cooling water in the intake side portion of the cylinder head 52.

  Each of the W / Js 501 and 502 has a longitudinal flow structure in which the cooling water flows from the cylinder block 51 and the cooling water flows out from the cylinder head 52. Further, the side from which the output of the engine 50 is taken is the rear side, and cooling water is allowed to flow in from the front side of the engine 50 and the cooling water is allowed to flow out from the rear side.

  As shown in FIG. 1, a plurality of cooling water circulation paths are formed in the cooling device 1A. As the cooling water circulation path, for example, there is a first circulation path C1 which is a circulation path in which the first W / J 501 is incorporated. The cooling water flowing through the first circulation path C1 is discharged from the W / P 11 and then flows through the first W / J 501 and further through the thermostat 13 or through the radiator 12 and the thermostat 13. Return to P11.

  The radiator 12 is a heat exchanger, and cools the cooling water by exchanging heat between the circulating cooling water and the air. The thermostat 13 switches the distribution route communicating with the W / P 11 from the entrance side. Specifically, the thermostat 13 sets the flow path that bypasses the radiator 12 when the coolant temperature is lower than a predetermined value, and sets the flow path that flows through the radiator 12 when the temperature of the cooling water is equal to or higher than the predetermined value.

  Further, as the cooling water circulation path, for example, there is a second circulation path C2 which is a circulation path in which the second W / J 502 is incorporated. The cooling water flowing through the second circulation path C2 is discharged from the W / P 11 and then flows through the flow rate control valve 14 and further passes through the thermostat 13 or to the W / P 11 via the radiator 12 and the thermostat 13. It comes to return.

  The flow rate control valve 14 is provided in a part of the second circulation path C2 after the circulation paths C1 and C2 are branched and in a part upstream of the engine 50. The flow rate adjusting valve 14 is a cooling capacity adjusting means that can adjust the cooling capacity of the second W / J 502 by adjusting the flow rate of the cooling water flowing through the second W / J 502.

  Further, the flow rate adjusting valve 14 is a cooling capacity adjusting means capable of suppressing the cooling capacity of the second W / J 502 without suppressing the cooling capacity of the first W / J 501. Specifically, for example, when the W / J 501 and 502 have both the cooling capacity of the first W / J 501 and the cooling capacity of the second W / J 502 at the time of high rotation and high load in which the cooling water flows. The cooling capacity adjusting means is capable of suppressing the cooling capacity of the second W / J 502 without suppressing the cooling capacity of the first W / J 501 with respect to the capacity.

  Furthermore, the flow rate adjusting valve 14 cools the first W / J 501 when the flow rate of the cooling water flowing through the second W / J 502 is adjusted so as to suppress the cooling capacity of the second W / J 502. The cooling capacity adjusting means is capable of adjusting the flow rate of the cooling water flowing through the first W / J 501 so as to increase the capacity.

  In the cooling device 1 </ b> A, the cooling water flowing through the first circulation path C <b> 1 is not circulated through the second W / J 502 until one cycle after the cooling water is pumped by the W / P 11. . In addition, the cooling water flowing through the second circulation path C2 is not circulated through the first W / J 501 until one cycle after the cooling water is pumped by the W / P 11. That is, in the cooling device 1A, the first W / J 501 and the second W / J 502 are incorporated in different coolant circulation paths. The first W / J 501 corresponds to the first coolant passage, and the second W / J 502 corresponds to the second coolant passage.

  FIG. 5 is a schematic configuration diagram of the ECU 70. The cooling device 1A further includes an ECU 70 that is an electronic control device. The ECU 70 includes a microcomputer including a CPU 71, a ROM 72, a RAM 73, and the like and input / output circuits 75 and 76. These components are connected to each other via a bus 74.

  The ECU 70 includes a crank angle sensor 81 for detecting the rotational speed of the engine 50, an air flow meter 82 for measuring the intake air amount, an accelerator opening sensor 83 for detecting the accelerator opening, and cooling water. Various sensors and switches such as a water temperature sensor 84 for detecting the temperature of the water are electrically connected. In this regard, the load of the engine 50 is detected by the ECU 70 based on the outputs of the air flow meter 82 and the accelerator opening sensor 83. Various control objects such as the W / P 11 and the flow rate control valve 14 are electrically connected to the ECU 70.

  The ROM 72 is configured to store a program in which various processes executed by the CPU 71 are described, map data, and the like. When the CPU 71 executes processing while using the temporary storage area of the RAM 73 based on a program stored in the ROM 72 as necessary, various control means, determination means, detection means, calculation means, and the like are functional in the ECU 70. To be realized.

  For example, in the ECU 70, control means for controlling the W / P 11 and the flow rate adjustment valve 14 is functionally realized. The control means performs control for driving the W / P 11 when cooling water is circulated through the engine 50. Thus, when the cooling water is circulated through the engine 50, the cooling water is circulated through the W / J 501. When circulating cooling water through the engine 50, for example, the engine is operating. In the case where the coolant is circulated through the engine 50, for example, a predetermined time may have elapsed after the engine cold start.

  In addition, when the cooling water is circulated through the engine 50, the control means is configured to circulate the cooling water through the second W / J 502. Also, the control for reducing the opening degree of the flow control valve 14 is performed. As a result, when the load of the engine 50 is a low / medium load, the flow rate of the cooling water flowing through the second W / J 502 is reduced as compared with the case of a high load.

  When the load of the engine 50 is high, the control means can fully open the flow control valve 14, for example. Further, when the load of the engine 50 is a low / medium load, the flow rate control valve 14 can be opened, for example, in a fully closed state or a mode in which boiling of the cooling water can be suppressed. In performing the control for driving the W / P 11, the control unit can perform the control so that the discharge amount increases as the rotational speed of the engine 50 increases, for example. In the cooling device 1A, the W / P 11, the flow rate adjustment valve 14, and the ECU 70 correspond to the cooling medium control means.

  Next, the operation of the ECU 70 will be described using the flowchart shown in FIG. The ECU 70 determines whether or not the engine is operating (step S1). If negative. W / P11 is stopped (step S7). And this flowchart is once complete | finished. On the other hand, if an affirmative determination is made, the ECU 70 drives the W / P 11 (step S2). Thereby, when circulating cooling water through the engine 50, the cooling water always flows through the first W / J 501.

  Subsequently, the ECU 70 detects the load of the engine 50 (step S3). Then, it is determined whether or not the detected load is a high load (step S4). If the determination is affirmative, the ECU 70 opens the flow rate adjustment valve 14 (step S5). If the determination is negative, the ECU 70 opens the valve with a smaller opening than when the load is high, including closing the valve (step S6). Thereby, when the load of the engine 50 is a low / medium load, the flow rate of the cooling water flowing through the second W / J 502 is reduced as compared with the case of a high load.

  Next, the effect of the cooling device 1A will be described. FIG. 7 is a diagram showing the heat transfer coefficient and the surface area ratio of the combustion chamber according to the crank angle. As shown in FIG. 7, it can be seen that the heat transfer coefficient increases near the top dead center of the compression stroke. As for the surface area ratio, it can be seen that the surface area ratio of the cylinder head 52 and the piston increases near the top dead center of the compression stroke. Therefore, it can be seen that the influence of the temperature of the cylinder head 52 is large on the cooling loss.

  On the other hand, knocking depends on the compression end temperature, and it can be seen that the surface area ratio of the cylinder 51a is large in the intake compression stroke that affects the compression end temperature. Therefore, it can be seen that the influence of the temperature of the cylinder 51a is large for knocking. Further, regarding knocking, the influence of temperature on the exhaust side portion of the cylinder 51a is greater than that on the intake side because of the intake air flowing into the combustion chamber.

  On the other hand, 1 A of cooling devices can cool the part by the side of the exhaust of the engine 50 by distribute | circulating cooling water to 1st W / J501. As a result, the exhaust side portion of the cylinder 51a can be cooled. Further, the portion on the exhaust side of the engine 50 is a portion that tends to become hot for the convenience of exhaust. For this reason, 1 A of cooling devices can suppress generation | occurrence | production of knocking suitably by distribute | circulating cooling water to 1st W / J501. At the same time, the reliability of the engine 50 can be ensured by cooling the portion around the spark plug 54.

  In addition, the cooling device 1A can reduce the cooling loss in the intake side portion of the engine 50 by limiting the flow rate of the cooling water flowing through the second W / J 502. Thus, the cooling loss can be reduced at the intake side portion of the cylinder head 52. Further, the cooling device 1A is provided with the first W / J 501 on the exhaust side of the engine 50 and the second W / J 502 on the intake side of the engine 50, so that a simple longitudinal flow structure that is relatively easy to manufacture. Can have.

  Therefore, the cooling device 1A can locally change the state of heat transfer with a simple longitudinal flow structure based on the above-described knowledge. And thereby, thermal efficiency can be improved by making the reduction of cooling loss and knock performance compatible.

  Specifically, when the cooling device 1A distributes the cooling water to the engine 50, the occurrence of knocking can be suitably suppressed by always supplying the cooling water to the first W / J 501. At the same time, the reliability of the engine 50 can be suitably secured. In addition, when the cooling water is circulated through the second W / J 502, the flow rate of the cooling water circulated through the second W / J 502 is higher when the load of the engine 50 is low and medium than when the load is high. By reducing it, the cooling loss can be reduced at low and medium loads. As a result, a reduction in cooling loss and a knocking performance can both be suitably achieved.

  Further, in the cooling device 1A, when the flow rate adjusting valve 14 adjusts the flow rate of the cooling water flowing through the second W / J 502 so as to suppress the cooling capacity of the second W / J 502, the first W The flow rate of the cooling water flowing through the first W / J 501 is adjusted so as to increase the cooling capacity of / J501. For this reason, the cooling device 1A can further cool the intake air. As a result, the occurrence of knocking can be more suitably suppressed.

  FIG. 8 is a schematic configuration diagram of the cooling device 1B. The cooling device 1B further includes an EGR device 21 and a first branch portion 22 as compared with the cooling device 1A. The EGR device 21 performs exhaust gas recirculation with respect to the engine 50. In other words, the engine 50 is an engine that performs exhaust gas recirculation.

  The EGR device 21 includes an EGR pipe 211, an EGR flow rate adjustment valve 212, and an EGR cooler 213. The EGR pipe 211 recirculates the exhaust gas to the engine 50. The EGR flow rate adjustment valve 212 adjusts the flow rate of exhaust gas recirculated to the engine 50. The EGR cooler 213 cools the exhaust gas recirculated to the engine 50 through heat exchange with the cooling water. The EGR cooler 213 corresponds to a cooler.

  The first branch portion 22 divides the cooling water flowing through the first W / J 501 and distributes it to the EGR cooler 213. The cooling water flowing through the first W / J 501 is the cooling water flowing through the first circulation path C1. Therefore, the cooling water flowing through the first W / J 501 is divided by dividing the cooling water flowing through the portion of the first circulation path C1 from when the circulation paths C1 and C2 branch to the merge. Can be shunted.

  In this regard, specifically, the first branching section 22 divides the cooling water flowing through the first W / J 501 downstream from the first W / J 501 and distributes it to the EGR cooler 213. The cooling water circulated through the EGR cooler 213 is merged at a portion of the first circulation path C1 that is downstream of the first branch portion 22 and upstream of the junction of the circulation paths C1 and C2. Can do.

  Next, the effect of the cooling device 1B will be described. Here, the EGR cooler 213 is provided to suppress the occurrence of knocking when the high-temperature exhaust gas is recirculated to the engine 50. However, if the cooling water flow to the EGR cooler 213 is reduced or the cooling water flow to the EGR cooler 213 is stopped to reduce the cooling loss of the engine 50, the exhaust gas to be recirculated will be reduced. There is a concern that the temperature will rise or the cooling water will boil.

  On the other hand, the cooling device 1B diverts the cooling water flowing through the first W / J 501 and distributes it to the EGR cooler 213. For this reason, the cooling device 1 </ b> B can suitably use the EGR device 21. As a result, fuel consumption can be further improved by exhaust gas recirculation. Moreover, it is possible to prevent the cooling performance of the first W / J 501 from being affected by diverting the cooling water flowing through the first W / J 501 downstream of the first W / J 501.

  FIG. 9 is a schematic configuration diagram of the cooling device 1C. The cooling device 1C further includes a heater core 31 and a second branch portion 32, as compared with the cooling device 1A. Similar changes can be made to the cooling device 1B, for example. The heater core 31 is used for heating the vehicle and heats the air by heat exchange with the circulating cooling water. The heater core 31 corresponds to a heater.

  The second branch portion 32 divides the cooling water flowing through the first W / J 501 and distributes it to the heater core 31. Specifically, the cooling water flowing through the first W / J 501 is diverted downstream from the first W / J 501 and flows through the heater core 31. The cooling water circulated through the heater core 31 may be merged in a portion of the first circulation path C1 downstream of the second branching section 32 and upstream of the junction of the circulation paths C1 and C2. it can.

  Next, the effect of the cooling device 1C will be described. The cooling device 1 </ b> C diverts the cooling water flowing through the first W / J 501 and distributes it to the heater core 31. For this reason, 1 C of cooling devices can suppress that the heating performance of a vehicle falls according to reducing the cooling loss of the engine 50. FIG. That is, it is possible to suitably use heating. Further, the cooling water flowing through the first W / J 501 is diverted downstream from the first W / J 501 so that the cooling water having a large amount of heat can be used for heating. As a result, the heating performance can be suitably improved.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

Cooling device 1A, 1B, 1C
W / P 11
Radiator 12
Thermostat 13
Flow control valve 14
EGR device 21
EGR cooler 213
First branch part 22
Heater core 31
Second branch part 32
Engine 50
1st W / J 501
Second W / J 502
Cylinder block 51
Cylinder head 52
Gasket 53
Spark plug 54
ECU 70

Claims (4)

A cylinder block and a cylinder head of an engine provided with a first cooling medium passage and a second cooling medium passage for circulating the cooling medium;
After the first cooling medium passage circulates the cooling medium to the exhaust side portion of the cylinder block, a predetermined area around the spark plug provided in the cylinder head of the cylinder head is formed. Including the exhaust side,
The second cooling medium passage is incorporated in a cooling medium circulation path different from the cooling medium circulation path in which the first cooling medium passage is incorporated, and the cooling medium is circulated to a portion of the cylinder block on the intake side. An engine cooling device that is circulated to a portion on the intake side of the cylinder head.   When the coolant is circulated through the engine, the load of the engine is reduced when the coolant is circulated through the first coolant passage and the coolant is circulated through the second coolant passage. The engine cooling device according to claim 1, further comprising: a cooling medium control unit that reduces a flow rate of the cooling medium flowing through the second cooling medium passage when the load is medium load than when the load is high. The engine is an engine in which exhaust gas recirculation is performed;
A cooler capable of cooling the exhaust gas recirculated to the engine by heat exchange with the circulating cooling medium, and a cooling medium flowing through the first cooling medium passage, and the first cooling medium flowing through the cooler. The engine cooling device according to claim 2, further comprising: 1 branch portion.   A heater capable of heating air by heat exchange with the circulating cooling medium, and a second branch portion for diverting the cooling medium flowing through the first cooling medium passage and flowing the cooling medium to the heater The engine cooling device according to claim 2 or 3, further comprising:

Images