JP2012188965A - Engine cooling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine cooling system that promptly eliminates deterioration in fuel consumption due to friction loss in the cold state while securing cooling performance for auxiliary machines by a simple configuration.SOLUTION: The engine cooling system includes: a bypass passage 17 for internally circulating cooling water in a water jacket 8; an auxiliary passage 20 that communicates between the upstream side and the downstream side of a water pump 10 and circulates cooling water supplied to auxiliary machines; and an electromagnetic valve 19 for opening/closing the bypass passage 17. When there is no local abnormal rise in the temperature in an engine body 5 in the cold state, the internal circulation of cooling water in the water jacket 8 is inhibited in order to efficiently accelerate warming-up of the engine body. On the other hand, when there is an abnormal local rise in the temperature in the engine body 5 in the cold state, cooling water in the water jacket 8 is internally circulated in order to smooth the temperature in the engine body 5, thereby also coping with heat damage or the like to the engine body 5.

Description

  The present invention relates to an engine cooling system that promotes warm-up by prohibiting or restricting circulation of cooling water to a radiator in a cold state.

  In general, a cooling system for a diesel engine or a gasoline engine for a vehicle is provided with a thermostat valve that blocks a cooling water passage that circulates cooling water to a radiator in order to promote warm-up of the engine at the time of cold start. Further, in this type of cooling system, a bypass passage is provided for internally circulating cooling water pumped from the water pump to the water jacket when the cooling passage is shut off by the thermostat valve.

  Furthermore, this type of cooling system effectively cools auxiliary equipment such as an EGR cooler even while the engine is warming up. In order to effectively cool auxiliary equipment such as an EGR cooler, or when the thermostat valve is closed. In addition, a number of techniques have been proposed in which a sub-passage through which cooling water can be circulated is separately provided and auxiliary machines are arranged on the sub-passage (see, for example, Patent Document 1).

JP 2007-263034 A

  By the way, in recent years, it has been demanded to improve the fuel efficiency of the engine at a high level. For this purpose, it is necessary to efficiently promote warm-up at the cold start and reduce the friction loss at an early stage. .

  On the other hand, for example, by interposing a clutch or the like between the output shaft of the engine and the water pump, and appropriately stopping the water pump when the engine is cold started, the internal circulation of the cooling water is stopped to warm up the engine. It can be promoted.

  However, if a clutch or the like is interposed between the output shaft of the engine and the water pump as described above, the structure may be complicated and the operation reliability of the water pump may be reduced. Furthermore, when the water pump is stopped, it may be difficult to sufficiently secure the cooling performance for the auxiliary machinery whose temperature rise is relatively fast.

  The present invention has been made in view of the above circumstances, and with a simple configuration, it is possible to cool an engine that can quickly eliminate deterioration in fuel consumption due to friction loss during cooling while securing the cooling performance of auxiliary equipment. The purpose is to provide a system.

  An engine cooling system according to an aspect of the present invention includes a water jacket formed inside an engine body, a cooling passage for circulating cooling water in the water jacket to a radiator, and the water passage interposed in the cooling passage. In a cooling system for an engine, comprising: a water pump that pumps cooling water to a jacket; and a thermostat valve that blocks the cooling passage during cooling and prohibits circulation of cooling water between the water jacket and the radiator. A bypass passage that internally circulates the cooling water in the water jacket, a sub-passage that connects the upstream side and the downstream side of the water pump to circulate the cooling water to the accessories, and opens and closes the bypass passage. And a valve.

  According to the engine cooling system of the present invention, with a simple configuration, deterioration of fuel consumption due to friction loss during cooling can be eliminated at an early stage while ensuring the cooling performance of auxiliary equipment.

Schematic configuration diagram showing the engine cooling system Flow chart showing valve control routine Explanatory drawing showing the circulating state of the cooling water when the engine is cold Explanatory drawing which shows the circulation state of the cooling water at the time of engine cold state and high load operation Explanatory drawing showing the circulating state of cooling water after engine warm-up (A) is explanatory drawing which shows transition of the oil temperature and cooling water temperature when it warms up in the state which closed the electromagnetic valve, (b) is the oil temperature and cooling water temperature when it warms up by opening an electromagnetic valve. Explanatory diagram showing the transition Exploded perspective view showing the engine body and oil cooler Cross section of the main part of the oil cooler attached to the engine body

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings relate to an embodiment of the present invention, FIG. 1 is a schematic configuration diagram showing an engine cooling system, FIG. 2 is a flowchart showing a valve control routine, and FIG. 3 shows a circulating state of cooling water when the engine is cold. FIG. 4 is an explanatory diagram showing the circulating state of the cooling water when the engine is cold and operating at a high load, FIG. 5 is an explanatory diagram showing the circulating state of the cooling water after the engine is warmed up, and FIG. (A) is explanatory drawing which shows transition of the oil temperature and cooling water temperature when it warms up in the state which closed the electromagnetic valve, (b) is the oil temperature and cooling water temperature when it warms up by opening an electromagnetic valve. FIG. 7 is an exploded perspective view showing the engine main body and the oil cooler, and FIG. 8 is a cross-sectional view of the main part of the oil cooler attached to the engine main body.

  In FIG. 1, reference numeral 1 denotes a water-cooled engine mounted on a vehicle such as an automobile, and in the present embodiment, a horizontally opposed diesel engine. A water jacket 8 is formed in the cylinder block 6 constituting the engine body 5 of the engine 1 and the cylinder heads 7 of the left and right banks. The discharge side of the engine-driven water pump 10 is connected to the cooling water inlet of the water jacket 8. It is connected. A thermostat valve 11 is disposed on the suction side of the water pump 10, and the inlet side of the thermostat valve 11 is connected to the radiator 13 via the cooling passage 12.

  On the other hand, the downstream sides of the water jackets 8 formed in the left and right banks are communicated with each other via a merging passage 15 disposed above the engine body 5, and the merging passage 15 is connected to the radiator via the cooling passage 16. 13 is connected.

  The merging passage 15 is connected to the suction side of the water pump 10 via a bypass passage 17, and an air conditioner heat core 18 is connected to the bypass passage 17 in parallel. Further, an electromagnetic valve 19 as a valve for opening and closing the bypass passage is interposed in the middle of the bypass passage 17.

  Further, the downstream side (suction side) of the water pump 10 communicates with the upstream side (discharge side) of the water pump 10 via the auxiliary passage 20. This sub-passage 20 is for constantly circulating cooling water while the water pump 10 is being driven (that is, while the engine 1 is being driven). For example, a turbocharger 21, an EGR cooler 22, and an oil cooler 23 are interposed.

  In the cooling system according to the present embodiment having such a circuit configuration, the thermostat valve 11 is mechanically opened and closed according to the cooling water temperature. For example, the thermostat valve 11 starts opening at 80 to 85 [° C.], and 95 to 100 Fully open at [℃].

  On the other hand, the electromagnetic valve 19 is controlled to open and close by an engine control unit (ECU) 30. In order to perform the opening / closing control of the electromagnetic valve 19, the ECU 30 includes, for example, a water temperature sensor 31 as a water temperature detecting means for detecting the cooling water temperature Tw of the water jacket 8, and the cooling water temperature of the water jacket 8 side and the auxiliary passage 20 side. A thermoelectric element 32 that detects a temperature difference as a current value I is connected.

  In the present embodiment, as shown in FIG. 1, the water temperature sensor 31 is disposed on, for example, the joining passage 15 and detects the cooling water temperature in the joining passage 15 as the cooling water temperature Tw of the water jacket 8. That is, in the present embodiment, the water temperature sensor 31 is disposed on the confluence passage 15 that communicates with the downstream side of the left and right water jackets 8, so that the water temperature sensor 31 is caused by heat convection or circulation of cooling water in the water jacket 8. The temperature of the cooling water smoothed to a predetermined level is detected as the cooling water temperature Tw.

  Moreover, in this embodiment, the thermoelectric element 32 is arrange | positioned in the site | part which the water jacket 8 and the subchannel | path 20 approach on the engine main body 5, for example. More specifically, for example, as shown in FIGS. 7 and 8, a bathtub-shaped circuit chamber 20 a formed in the middle of the sub-passage 20 is opened at a portion close to the cylinder head 7 in the upper part of the cylinder block 6. ing. An oil cooler 23 is fixed in a liquid-tight manner at a position where the circuit chamber 20a is closed on the deck surface of the engine body 5, and a cooling circuit 23a protruding from the lower portion of the oil cooler 23 is provided in the circuit chamber 20a. Contained. The bottom of the circuit chamber 20a is disposed close to a part of the water jacket 8 formed along the outer periphery of the cylinder liner 9 in the vicinity of the combustion chamber 9a, and has a communication hole 6a that opens at the bottom of the circuit chamber 20a. Via the water jacket 8. Further, a plate-like thermoelectric element 32 is disposed in the communication hole 6a, and the communication hole 6a is liquid-tightly closed through an O-ring 32a provided around the thermoelectric element 32. As a result, one surface of the thermoelectric element 32 is exposed to a portion that is significantly susceptible to the influence of combustion heat in the water jacket 8, and the other surface is exposed to the circuit chamber 20 a that is in the middle of the sub-passage 20. ing. The thermoelectric element 32 generates a current I corresponding to the temperature difference between the cooling water temperatures on the water jacket 8 side and the auxiliary passage 20 side. That is, in the present embodiment, the thermoelectric element 32 has a higher current as the temperature difference between the cooling water temperature in the vicinity of the combustion chamber 9 a that can locally become high in the water jacket 8 and the cooling water temperature in the auxiliary passage 20 increases. I is generated.

  As a control for the electromagnetic valve 19, the ECU 30 closes the electromagnetic valve 19 to circulate the cooling water in the water jacket 8 when the engine 1 (engine body 5) is in a cold state where the cooling water temperature Tw is lower than the set threshold value Tth1. By prohibiting, heat exchange between the cooling water in the water jacket 8 and the engine body 5 side is suppressed, and warm-up is promoted. On the other hand, when the coolant temperature Tw becomes equal to or higher than the set threshold value Tth1, the ECU 30 determines completion of warm-up and controls the electromagnetic valve 19 to open. However, the ECU 30 determines that the current value I generated in the thermoelectric element 32 is equal to or greater than the set threshold value Ith1 and the engine 1 is in a high load operation even in the cold state before determining the completion of warm-up. In order to prevent the engine body 5 from being seized due to local overheating, the electromagnetic valve 19 is controlled to open and the cooling water is circulated in the water jacket 8. Thus, in this embodiment, ECU30 has a function as a valve control means.

  Next, the opening / closing control of the electromagnetic valve 19 executed by the ECU 30 will be described according to the flowchart of the valve control routine shown in FIG. This routine is repeatedly executed every set time. When the routine starts, the ECU 30 checks in step S101 whether or not the electromagnetic valve 19 is currently closed.

  In step S101, the ECU 30 proceeds to step S102 if it is determined that the electromagnetic valve 19 is in the closed state, and proceeds to step S105 if it is determined that the electromagnetic valve 19 is in the open state.

  When the process proceeds from step S101 to step S102, the ECU 30 checks whether or not the cooling water temperature Tw detected by the water temperature sensor 31 is equal to or higher than a set threshold value Tth1.

  In step S102, when the coolant temperature Tw is equal to or higher than the set threshold value Tth1, the ECU 30 determines that the warm-up of the engine body 5 has been sufficiently promoted, and proceeds to step S104.

  On the other hand, when the coolant temperature Tw is less than the set threshold value Tth1 in step S102, the ECU 30 determines that the engine body 5 is not yet warmed up and the friction of the sliding portion is high, and step S103. Proceed to

  When the process proceeds from step S102 to step S103, the ECU 30 checks whether or not the current value I generated in the thermoelectric element 32 is equal to or greater than the set threshold value Ith1.

  In step S103, if the current value I is less than the set threshold value Ith1, the ECU 30 determines that the temperature difference between the cooling water temperature in the sub-passage 20 and the cooling water temperature in the water jacket 8 is within a predetermined range. It is determined that there is a low possibility that the temperature inside is abnormally high, and the routine is exited.

  On the other hand, when the current value I is equal to or greater than the set threshold value Ith1 in step S103, the ECU 30 has a coolant temperature near the combustion chamber 9a in the water jacket 8 higher than the coolant temperature in the sub-passage 20 by a predetermined value or more. It is determined that there is a high possibility that the temperature in the engine body 5 is locally abnormally increased due to the high load operation, and the process proceeds to step S104.

  Then, when the process proceeds from step S102 or step S103 to step S104, the ECU 30 opens the electromagnetic valve 19 and starts the internal circulation of the cooling water in the water jacket 8, and then exits the routine.

  Further, when the process proceeds from step S101 to step S105, the ECU 30 checks whether or not the cooling water temperature Tw detected by the water temperature sensor 31 is equal to or lower than the set threshold value Tth2. Here, the setting threshold value Tth2 can be set to a value equal to the setting threshold value Tth1, but is set to a value lower than the setting threshold value Tth1 in order to prevent control hunting.

  In step S105, if the coolant temperature Tw is higher than the set threshold value Tth2, the ECU 30 determines that the engine body 5 is sufficiently warmed up and exits the routine as it is.

  On the other hand, when the coolant temperature Tw is equal to or lower than the set threshold value Tth2 in step S105, the ECU 30 determines that the engine body 5 is not sufficiently warmed up, and proceeds to step S106.

  When the process proceeds from step S105 to step S106, the ECU 30 checks whether or not the current value I detected by the thermoelectric element 32 is equal to or less than the set threshold value Ith2. Here, the setting threshold value Ith2 can be set to a value equal to the setting threshold value Ith1, but is set to a value lower than the setting threshold value Ith1 in order to prevent control hunting.

  In step S106, when the current value I is higher than the set threshold value Ith2, the ECU 30 determines that there is a high possibility that the temperature in the engine body 5 is locally abnormally increased due to the high load operation of the engine 1. And exit the routine.

  On the other hand, when the current value I is equal to or smaller than the set threshold value Ith2 in step S106, the ECU 30 does not sufficiently warm up the engine body 5 and the local abnormal increase in the temperature of the engine body 5 has been resolved. The process proceeds to step S107.

  Then, when the process proceeds from step S106 to step S107, the ECU 30 closes the electromagnetic valve 19, prohibits the internal circulation of the cooling water in the water jacket 8, and then exits the routine.

  By such control, for example, as indicated by hatching in FIG. 3, the cooling water is basically circulated only in the auxiliary passage 20 when the engine 1 is in a cold state. That is, when the engine 1 is in a cold state, the thermostat valve 11 is in a closed state and the circulation of the cooling water to the radiator 13 is blocked. Further, since the electromagnetic valve 19 is controlled to be closed by the above-described control, the internal circulation of the cooling water in the water jacket 8 is also prohibited, and the cooling water is circulated only in the auxiliary passage 20. Then, the circulation of the cooling water in the water jacket 8 is prohibited, so that the transfer of combustion heat to the cooling water in the engine body 5 is suppressed. Accordingly, much of the combustion heat is transmitted to the engine body 5 itself, and warming up of the engine body 5 is efficiently promoted. That is, by prohibiting the circulation of the cooling water in the water jacket 8, for example, as shown in FIG. 6A, the oil of the oil that lubricates the inside of the engine body 5 than the cooling water temperature Tw in the water jacket 8. The temperature To rises relatively quickly, and the deterioration of fuel consumption due to friction loss during cold start can be resolved early. FIG. 6B shows a temperature transition of the cooling water temperature Tw and the oil temperature To when the cooling water in the water jacket 8 is internally circulated during the cold start.

  In this case, a sub-passage 20 is provided separately from the bypass passage 17 for internally circulating the cooling water of the water jacket 8, and the cooling water is always circulated in the sub-passage 20, and cooling is performed on the sub-passage 20. By arranging the necessary auxiliary equipment, the cooling performance of the auxiliary equipment can be ensured accurately.

  Moreover, since the auxiliary passage 20 through which the cooling water always circulates is provided, it is not necessary to stop the water pump 10 even when the internal circulation of the cooling water in the water jacket 8 is prohibited, and the output shaft of the engine 1 and the water pump Since it is not necessary to add a mechanism such as a clutch between the first and second members, the structure can be simplified.

  On the other hand, for example, as shown by hatching in FIG. 5, when the warm-up of the engine body 5 proceeds and the cooling water temperature Tw in the water jacket 8 rises due to convection by thermal diffusion, the cooling water in the water jacket 8 Circulates mainly with the radiator 13. That is, when the engine body 5 is warmed up, the electromagnetic valve 19 is controlled to open as the coolant temperature Tw rises. When the thermostat valve 11 is warmed and opened along with the internal circulation of the heated coolant, the coolant in the water jacket 8 circulates mainly with the radiator 13.

  Further, for example, as indicated by hatching in FIG. 4, if the temperature in the engine body 5 rises abnormally locally due to high load operation of the engine 1 during warm-up, the cooling water in the water jacket 8 Is internally circulated through the bypass passage 17. That is, when the temperature in the engine main body 5 rises abnormally locally, the temperature difference from the auxiliary passage 20 side increases, the current I generated in the thermoelectric element 32 increases, and the electromagnetic valve 19 is controlled to open. Thereby, the cooling water in the water jacket 8 is internally circulated through the bypass passage 17, and local overheating in the engine body 5 can be eliminated by the internal circulation of the cooling water.

  According to such an embodiment, the bypass passage 17 that internally circulates the cooling water in the water jacket 8, and the auxiliary pump that circulates the cooling water to the accessories by communicating the upstream side and the downstream side of the water pump 10. A passage 20 and an electromagnetic valve 19 for opening and closing the bypass passage 17 are provided. When the temperature in the engine body 5 does not rise abnormally locally in the cold state, internal circulation of the cooling water in the water jacket 8 is performed. Can be prohibited to efficiently promote warm-up. On the other hand, when the temperature in the engine body 5 rises abnormally locally during the cold state, the thermostat valve is obtained by internally circulating the cooling water in the water jacket 8 to smooth the temperature in the engine body 5. It is possible to cope with heat damage of the engine body 5 without excessively cooling the cooling water by opening the valve 11 or the like.

  Moreover, the control of the electromagnetic valve 19 in the cold state is based on the current I generated in accordance with the temperature difference of the cooling water temperature between the water jacket 8 side and the auxiliary passage 20 side by adding a thermoelectric element 32 to the engine body 5. By carrying out, it is possible to achieve both warm-up promotion during cold operation and countermeasures against heat damage during high-load operation with a simple configuration and simple control.

  In this case, a part of the sub-passage 20 is arranged close to a part of the water jacket 8 in the vicinity of the combustion chamber 9 a of the engine body 5, and between these adjacent water jacket 8 and the sub-passage 20. By interposing the thermoelectric element 32, a change in the amount of heat generated during high load operation can be directly reflected in the control of the electromagnetic valve 19.

  Furthermore, by opening the circuit chamber 20a that houses the cooling circuit 23a of the oil cooler 23 in the region on the sub-passage 20 to which the thermoelectric element 32 is attached, the workability of attaching the thermoelectric element 32 can be improved.

  In addition, this invention is not limited to each embodiment described above, A various deformation | transformation and change are possible, and they are also in the technical scope of this invention.

  For example, in the above-described embodiment, an example in which it is determined that the engine body 5 is locally overheated based on the current I generated in the thermoelectric element 32 and the opening / closing control of the electromagnetic valve 19 is performed has been described. The present invention is not limited to this. For example, the engine load is estimated from the intake air amount or the like of the engine 1, and the engine body 5 is indirectly overheated based on the estimated engine load. It is also possible to determine whether or not.

  Further, the arrangement of turbochargers, EGR coolers, and oil coolers as auxiliary machines can be changed as appropriate, and other auxiliary machines can be added as appropriate.

  In the present embodiment, the horizontally opposed diesel engine has been described. However, the present invention can also be applied to a V-type, an in-line diesel engine, and a gasoline engine.

  Furthermore, although an electromagnetic valve has been described as an example of a valve that opens and closes the bypass passage, various control valves that are electrically driven can be used.

DESCRIPTION OF SYMBOLS 1 ... Engine 5 ... Engine main body 6 ... Cylinder block 6a ... Communication hole 7 ... Cylinder head 8 ... Water jacket 9 ... Cylinder liner 9a ... Combustion chamber 10 ... Water pump 11 ... Thermostat valve 12 ... Cooling passage 13 ... Radiator 15 ... Confluence passage DESCRIPTION OF SYMBOLS 16 ... Cooling passage 17 ... Bypass passage 18 ... Heat core 19 ... Electromagnetic valve 20 ... Sub-passage 20a ... Circuit room 21 ... Turbocharger (auxiliaries)
22 ... EGR cooler (auxiliaries)
23… Oil cooler (auxiliary equipment)
23a ... Cooling circuit 30 ... Engine control unit (valve control means)
31 ... Water temperature sensor (water temperature detection means)
32 ... Thermoelectric element 32a ... O-ring

Claims (2)

A water jacket formed inside the engine body, a cooling passage for circulating cooling water in the water jacket to the radiator, a water pump interposed in the cooling passage and pumping the cooling water to the water jacket, In a cooling system for an engine, comprising: a thermostat valve that shuts off the cooling passage during operation and prohibits circulation of cooling water between the water jacket and the radiator;
A bypass passage for internally circulating the cooling water in the water jacket;
A sub-passage that circulates cooling water to the accessories by communicating the upstream side and the downstream side of the water pump;
An engine cooling system comprising: a valve that opens and closes the bypass passage. Water temperature detecting means for detecting the cooling water temperature of the water jacket;
Valve control means for controlling the valve based on the cooling water temperature,
2. The engine cooling system according to claim 1, wherein the valve control means controls the valve to be closed when a cooling water temperature of the water jacket is equal to or lower than a set threshold value.

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