JP2011021495A - Engine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine control device improving fuel economy of an engine by suppressing deterioration of durability of a cylinder bore caused by a sudden drop in temperature of the cylinder bore without increasing the weight of the cylinder bore. <P>SOLUTION: The engine 1 includes a cooling water circulation system circulating cooling water through a cooling water passage 10 in the order of the cylinder block 3 and cylinder head 4 of the engine 1 when an electric water pump 11 is normally rotated. An electronic control device 20 operates the water pump 11 when a cooling water temperature THW exceeds a predetermined temperature T1 while stopping the water pump 11 when the cooling water temperature THW inside an engine body 2 is lower than the predetermined temperature T1. When the cooling water temperature THW inside of the engine body 2 exceeds the predetermined temperature T1, the water pump 11 is operated to rotate backward. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an engine control device including a cooling water circulation system in which cooling water circulates through a cooling water passage in the order of a cylinder block and a cylinder head that constitute an engine main body during normal rotation of a water pump.

  As a control device for this type of engine, for example, there is one described in Patent Document 1. FIG. 4 shows a schematic configuration of a cooling water circulation system of an engine to which a conventional general control device is applied, including the one described in Patent Document 1.

  As shown in the figure, the engine 101 includes an engine body 2 including a cylinder block 103 and a cylinder head 104. Further, the engine 101 is provided with a cooling water passage 110 as a flow path through which the cooling water circulates. The cooling water passage 110 is provided with an engine-driven water pump 111 that sucks and discharges cooling water. A block-side water jacket 113 that forms part of the cooling water passage 110 is formed inside the cylinder block 103, and a head-side water jacket 114 that forms part of the cooling water passage 110 is formed inside the cylinder head 104.

  In the cooling water passage 110, a main passage 115 is connected between the downstream end portion of the head side water jacket 114 and the upstream end portion of the block side water jacket 113. A radiator 116 for cooling the cooling water is provided in the middle of the main passage 115. The main passage 115 is connected to a bypass passage 117 that connects the upstream portion and the downstream portion of the radiator 116 to bypass the radiator 116. Further, at the connection portion between the main passage 115 and the downstream end portion of the bypass passage 117, the cooling water flowing through each of the water jackets 113 and 114 during the forward rotation of the water pump 111 is from the bypass passage 117. A thermostat 118 is provided for switching between the radiator 116 and the radiator 116.

  In the engine 101 provided with such a cooling water circulation system, when the temperature of the cooling water is low, such as at the time of cold start, the inflow of the cooling water from the radiator 116 to the block-side water jacket 113 is prohibited through the thermostat 118 and the bypass passage 117 is provided. Allows the cooling water to flow into the block-side water jacket 113. Thus, the cooling water cooled in the radiator 116 is prohibited from flowing into the water jackets 113 and 114 to promote warm-up of the engine body 102. Since the engine-driven water pump is connected to the output shaft of the engine 101, the engine-driven water pump is always in a driving state during operation of the engine 101.

  In recent years, engines that employ electric water pumps instead of engine-driven water pumps have been developed. In an engine equipped with such an electric water pump, the water pump can be operated independently of the rotation of the output shaft of the engine. Therefore, when the temperature of the cooling water inside the engine body is lower than a predetermined temperature (for example, 70 ° C.), the water pump is stopped and the block-side water jacket from the outside of the engine body is stopped in order to promote warm-up of the engine body. It is conceivable to regulate the flow of low-temperature cooling water into the water.

JP 2004-44507 A

  However, as described above, when the temperature of the cooling water inside the engine body is lower than the predetermined temperature, the water pump is stopped, and the water pump is operated when the temperature of the cooling water becomes equal to or higher than the predetermined temperature. Then, the following problems will occur. That is, when the temperature of the cooling water inside the engine main body becomes equal to or higher than the predetermined temperature, the temperature of the cooling water outside the engine main body is still low, so that the low-temperature cooling water passes through the cooling water passage inside the cylinder block. As a result of flowing into the vicinity of the cylinder bore, there is a possibility that the temperature of the cylinder bore is rapidly decreased. For this reason, conventionally, measures such as increasing the thickness of the cylinder bore to some extent are used to prevent the durability of the cylinder bore from being lowered due to a sudden temperature drop of the cylinder bore. However, in this case, a new problem such as an increase in the weight of the cylinder bore and an increase in the weight of the engine and a deterioration in the fuel consumption of the engine cannot be avoided.

  The present invention has been made in view of such circumstances, and the object of the present invention is to suppress a decrease in the durability of the cylinder bore caused by a rapid temperature drop of the cylinder bore without increasing the weight of the cylinder bore, and An object of the present invention is to provide an engine control device capable of improving fuel consumption.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
(1) The invention according to claim 1 is applied to an engine including a cooling water circulation system in which cooling water circulates through a cooling water passage in the order of a cylinder block and a cylinder head constituting the engine main body at the time of forward rotation of the water pump. When the temperature of the cooling water inside the engine body is lower than a predetermined temperature, the water pump is stopped, and the water pump is activated when the temperature of the cooling water inside the engine body becomes equal to or higher than the predetermined temperature. A gist of the engine control device is that the water pump is operated in reverse rotation when the temperature of the cooling water inside the engine main body is equal to or higher than the predetermined temperature.

  According to this configuration, when the temperature of the cooling water inside the engine body becomes equal to or higher than the predetermined temperature and the water pump is operated, the cooling water circulates in the order of the cylinder head and the cylinder block of the engine through the cooling water passage. For this reason, first, cooling water that has already been heated in the cylinder head and has a high temperature flows into the cylinder bore formed in the cylinder block while the water pump is stopped. Thereby, compared with the case where the water pump is operated in the forward rotation, the high-temperature cooling water can be caused to flow into the cooling water passage in the vicinity of the cylinder bore, and the occurrence of a rapid temperature drop in the cylinder bore can be suppressed. Therefore, without increasing the weight of the cylinder bore, it is possible to suppress a decrease in the durability of the cylinder bore due to a rapid temperature drop of the cylinder bore, and to improve the fuel efficiency of the engine.

(2) The invention according to claim 2 is the engine control apparatus according to claim 1, characterized in that the water pump is an electric pump.
According to this configuration, it is possible to easily realize a configuration for operating the water pump by reverse rotation.

  (3) The invention according to claim 3 is the engine control apparatus according to claim 2, wherein the water pump has a smaller minimum discharge flow rate of cooling water during reverse rotation than during normal rotation. When the temperature of the cooling water inside the engine main body is equal to or higher than the predetermined temperature and the water pump is operated in reverse rotation, the discharge flow rate by the water pump is made smaller than the minimum discharge flow rate during forward rotation. It is a summary.

  By operating the water pump in the reverse rotation, when all the cooling water already heated in the cylinder head and being high temperature flows out from the cooling water passage in the vicinity of the cylinder bore while the water pump is stopped, Thereafter, still low-temperature cooling water outside the engine body flows into the engine body. For this reason, even if the water pump is operated in the reverse rotation, when the cooling water discharge flow rate by the water pump is relatively large, such low-temperature cooling water flows from the cylinder head in the cooling water passage inside the cylinder head. Before being heated by heat, it flows into the vicinity of the cylinder bore of the cooling water passage in the cylinder block, and there is a possibility that the deterioration of the durability of the cylinder bore due to the rapid temperature drop of the cylinder bore cannot be suppressed accurately.

On the other hand, in some electric pumps, the minimum discharge flow rate of cooling water during reverse rotation is smaller than during normal rotation.
According to the said structure, when operating a water pump by reverse rotation, the discharge flow rate of the cooling water by a water pump becomes small. As a result, it is possible to lengthen the period during which the low-temperature cooling water that has flowed into the cooling water passage inside the cylinder head from the outside of the engine body is present in the passage, that is, the period during which it is heated by the heat of the cylinder head. Therefore, the temperature of the cooling water flowing in the vicinity of the cylinder bore in the cooling water passage can be maintained high, and the deterioration of the durability of the cylinder bore due to the rapid temperature drop of the cylinder bore can be accurately suppressed.

  (4) The invention according to claim 4 is the engine control device according to claim 3, wherein the temperature of the cooling water inside the engine body is equal to or higher than the predetermined temperature and the water pump is operated in reverse rotation. The gist is that the discharge flow rate of the water pump is the minimum discharge flow rate during reverse rotation.

  According to this configuration, when the water pump is operated in reverse rotation, the cooling water discharge flow rate by the water pump becomes the smallest. As a result, it is possible to further increase the period during which the low-temperature cooling water that has flowed into the cooling water passage inside the cylinder head from the outside of the engine main body exists in the passage, that is, the period during which it is heated by the heat of the cylinder head. Therefore, the temperature of the cooling water flowing into the vicinity of the cylinder bore in the cooling water passage can be maintained higher, and the deterioration of the durability of the cylinder bore caused by the rapid temperature drop of the cylinder bore can be more accurately suppressed. Become.

  (5) The invention according to claim 5 is the engine control device according to any one of claims 1 to 4, wherein the reference temperature of the cooling water inside the engine body is higher than the predetermined temperature. The gist of the invention is that the water pump is operated in a normal rotation when the temperature becomes higher than the temperature.

  According to this configuration, cooler cooling water can flow into the cooling water passage in the vicinity of the cylinder bore, and the temperature of the cylinder bore rises excessively, as compared with a configuration in which the water pump is continuously operated in reverse rotation. This can be suppressed accurately.

  (6) The invention according to claim 6 is the engine control apparatus according to any one of claims 1 to 4, wherein a reference time has elapsed since the water pump was operated in reverse rotation. The gist of the invention is to operate the water pump in a normal rotation.

  According to this configuration, cooler cooling water can flow into the cooling water passage in the vicinity of the cylinder bore, and the temperature of the cylinder bore rises excessively, as compared with a configuration in which the water pump is continuously operated in reverse rotation. This can be suppressed accurately.

The schematic diagram which shows schematic structure of the cooling water circulation system about one Embodiment of the control apparatus of the engine which concerns on this invention. The flowchart which shows the process sequence of the operation control of the water pump in the embodiment. It is a time chart for demonstrating the effect | action of the embodiment, Comprising: The time chart which shows the time transition of the temperature of a cylinder bore vicinity. The schematic diagram which shows schematic structure of the cooling water circulation system about the control apparatus of the conventional engine.

Hereinafter, an embodiment in which an engine control device according to the present invention is embodied as a vehicle-mounted engine control device will be described with reference to FIGS. 1 to 3.
In FIG. 1, the schematic structure of the cooling water circulation system is shown about the engine 1 to which the control apparatus which concerns on this embodiment is applied.

  As shown in the figure, the engine 1 includes an engine body 2 including a cylinder block 3 and a cylinder head 4. Further, the engine 1 is provided with a cooling water passage 10 as a flow path through which the cooling water circulates. A block-side water jacket 13 that forms part of the cooling water passage 10 is formed inside the cylinder block 3, and a head-side water jacket 14 that forms part of the cooling water passage 10 is formed inside the cylinder head 4. The block-side water jacket 13 and the head-side water jacket 14 are connected in series. The cooling water passage 10 is provided with an electric water pump 11 that sucks and discharges the cooling water. Here, the water pump includes a motor capable of rotating in the forward and reverse directions and an impeller coupled to the output shaft of the motor (both not shown). The cooling water flows through the block side water jacket 13 and the head side water jacket 14 in this order. On the other hand, when the impeller is rotated reversely by the motor, cooling water flows through the cooling water passage 10 in the order of the head side water jacket 14 and the block side water jacket 13. The water pump 11 has a smaller cooling water discharge flow rate during reverse rotation than during normal rotation.

  In the following, for convenience of explaining the configuration of the cooling water circulation system, “upstream side” and “downstream side” indicate upstream side and downstream side with respect to the flow direction of the cooling water when the water pump 11 is rotated forward. To do.

  In the cooling water passage 10, a main passage 15 is connected between the downstream end portion of the head side water jacket 14 and the upstream end portion of the block side water jacket 13. A radiator 16 for cooling the cooling water is provided in the middle of the main passage 15. Further, a bypass passage 17 that connects the upstream portion and the downstream portion of the radiator 16 and bypasses the radiator 16 is connected to the main passage 15. In addition, at the connection portion between the main passage 15 and the downstream end portion of the bypass passage 17, the cooling water flowing through each of the water jackets 13 and 14 during the forward rotation of the water pump 11 is from the bypass passage 17. A thermostat 18 is provided for switching between the radiator 16 and the radiator 16.

  The vehicle is equipped with an electronic control unit 20 that executes various controls of the engine 1 including the operation control of the water pump 11. The electronic control unit 20 is a CPU that executes various arithmetic processes related to various controls, a ROM that stores programs and data necessary for various controls, a RAM that temporarily stores CPU calculation results, and signals to and from the outside. It is configured with input / output ports for input / output.

  The input port of the electronic control unit 20 includes a water temperature sensor 21 that is provided in the cylinder head 4 and detects the temperature (hereinafter referred to as “cooling water temperature”) THW at the downstream end of the head-side water jacket 14. Various sensors such as one ignition switch 22 are connected.

  In this embodiment, since the water pump 11 can be operated independently of the rotation of the output shaft of the engine 1, when the coolant temperature THW is lower than a predetermined temperature (here, 70 ° C.), the engine In order to promote warm-up of the main body 2, it is conceivable that the water pump 11 is stopped and the low-temperature cooling water is restricted from flowing into the block-side water jacket 13 from the outside of the engine main body 2.

  However, when the water pump 11 is stopped when the cooling water temperature THW is lower than the predetermined temperature T1, the water pump 11 is operated when the cooling water temperature THW becomes equal to or higher than the predetermined temperature T1, This will cause problems. That is, when the cooling water temperature THW becomes equal to or higher than the predetermined temperature T1, the temperature of the cooling water outside the engine body 2 is still low, so that the low temperature cooling water flows into the vicinity of the cylinder bore of the block-side water jacket 13. A sudden temperature drop of the cylinder bore occurs. For this reason, conventionally, measures such as increasing the thickness of the cylinder bore to some extent are used to prevent the durability of the cylinder bore from being lowered due to a sudden temperature drop of the cylinder bore. However, in this case, a new problem such as an increase in the weight of the cylinder bore and an increase in the weight of the engine and a deterioration in the fuel consumption of the engine cannot be avoided.

  Therefore, in the present embodiment, when the coolant temperature THW in the engine body 2 becomes equal to or higher than the predetermined temperature T1, the water pump 11 is operated in the reverse rotation, so that the head side water jacket 14 and the block side water jacket 13 are operated. The cooling water is circulated in order. As a result, first, cooling water that has already been heated and heated in the cylinder head 4 is caused to flow into the cylinder bores formed in the cylinder block 3 while the water pump 11 is in a stopped state. And by this, compared with the case where the water pump 11 is operated at normal rotation, high temperature cooling water is caused to flow in the vicinity of the cylinder bore of the block-side water jacket 13 so as to suppress the occurrence of a rapid temperature drop of the cylinder bore. I have to. As a result, the decrease in the durability of the cylinder bore due to the rapid temperature drop of the cylinder bore is suppressed without increasing the weight of the cylinder bore, and the fuel consumption of the engine 1 is improved.

  However, by operating the water pump 11 in the reverse rotation, all the cooling water that has already been heated in the cylinder head 4 and is at a high temperature while the water pump 11 is in a stopped state is all blocked by the block-side water jacket 13. After that, the low-temperature cooling water outside the engine body 2 flows into the engine body 2 after that. Therefore, even if the water pump 11 is operated in the reverse rotation, when the discharge rate of the cooling water by the water pump 11 is made relatively large, such low-temperature cooling water is discharged from the cylinder head 4 in the head-side water jacket 14. Before being heated by this heat, it flows into the block-side water jacket 13 and there is a possibility that the deterioration of the durability of the cylinder bore due to the rapid temperature drop of the cylinder bore cannot be suppressed accurately.

  Therefore, in this embodiment, when the coolant temperature THW in the engine body 2 is equal to or higher than the predetermined temperature T1 and the water pump 11 is operated in reverse rotation, the discharge flow rate by the water pump 11 is set to the minimum discharge flow rate in reverse rotation. By doing so, the discharge flow rate of the cooling water by the water pump 11 is minimized. As a result, the period during which the low-temperature cooling water that has flowed into the head-side water jacket 14 from the outside of the engine body 2 exists in the water jacket 14, that is, the period heated by the heat of the cylinder head, is lengthened. In FIG. 13, the temperature THW of the cooling water flowing in the vicinity of the cylinder bore is maintained at a high level, and the deterioration of the durability of the cylinder bore due to the rapid temperature drop of the cylinder bore can be more accurately suppressed.

  Further, if the water pump 11 is continuously operated in the reverse rotation, the temperature of the cylinder bore rises excessively. Therefore, in the present embodiment, the reference value for the coolant temperature THW in the engine body 2 is higher than the predetermined temperature T1. When the temperature becomes T2 (90 ° C. in this case) or higher, the water pump 11 is operated in the forward rotation. As a result, compared with the case where the water pump 11 is continuously operated in the reverse rotation, it is possible to accurately increase the temperature of the cylinder bore by allowing cooler cooling water to flow into the block-side water jacket 13. I try to suppress it.

  Next, with reference to FIG. 2, the process sequence of the operation control of the water pump 11 according to the present embodiment will be described. FIG. 2 is a flowchart showing a processing procedure of the operation control of the water pump, and is repeatedly executed at predetermined intervals during the operation of the engine 1.

  As shown in the figure, in this series of processing, first, it is determined whether or not the coolant temperature THW is lower than a predetermined temperature T1 (here, 70 ° C.) (step S101). Accordingly, when it is determined that the coolant temperature THW is lower than the predetermined temperature T1 as in the cold start (step S101: “YES”), the water pump 11 is then stopped (step S102). A series of processing is once ended.

  On the other hand, when the cooling water temperature THW rises and it is determined that the cooling water temperature THW is equal to or higher than the predetermined temperature T1 (step S101: “NO”), next, the reference temperature at which the cooling water temperature THW is higher than the predetermined temperature T1. It is determined whether it is lower than T2 (here, 90 ° C.) (step S103). Therefore, when it is determined that the cooling water temperature THW is lower than the reference temperature T2 immediately after the cooling water temperature THW increases and becomes equal to or higher than the predetermined temperature T1 (step S103: “YES”), then the water pump Reverse rotation control for operating 11 in reverse rotation is executed (step S104), and this series of processes is temporarily terminated.

  On the other hand, when the cooling water temperature THW further rises and it is determined that the cooling water temperature THW is equal to or higher than the reference temperature T2 (step S103: “NO”), next, the water pump 11 is operated in the forward rotation. Rotation control is executed (step S105), and this series of processes is temporarily terminated.

  Next, the time transition of the temperature around the cylinder bore at the time of cold start will be described with reference to the time chart of FIG. In FIG. 3, the time transition when the operation control of the water pump 11 of the present embodiment is executed is shown by a solid line, and the time transition when the operation control of the conventional water pump 11 is executed is shown by a one-dot chain line. Show.

  As shown in the figure, when the engine 1 is started at time t1, the coolant temperature THW at this time is lower than a predetermined temperature T1, and the water pump is thereby stopped, so that the temperature around the cylinder bore is reduced. It will rise rapidly. When the coolant temperature THW reaches the predetermined temperature T1 at time t2, in the operation control of the conventional water pump 11, the water pump 11 is operated in the normal rotation. As a result, as indicated by the alternate long and short dash line in the figure, the low-temperature cooling water outside the engine body 2 flows into the vicinity of the cylinder bore of the block-side water jacket 13, resulting in a rapid decrease in the temperature around the cylinder bore. To come.

  On the other hand, in the operation control of the water pump 11 of the present embodiment, the water pump 11 is operated by reverse rotation at time t2. As a result, as indicated by the solid line in the figure, the cylinder bore formed in the cylinder block 3 is first heated in the cylinder head 4 while the water pump 11 is stopped, and the As a result, the temperature around the cylinder bore gradually rises.

According to the engine control apparatus according to the present embodiment described above, the following effects can be obtained.
(1) The engine 1 includes a cooling water circulation system in which cooling water circulates through the cooling water passage 10 in the order of the cylinder block 3 and the cylinder head 4 of the engine 1 when the water pump 11 rotates forward. The electronic control unit 20 stops the water pump 11 when the cooling water temperature THW in the engine body 2 is lower than the predetermined temperature T1, while the water pump 11 is turned off when the cooling water temperature THW becomes equal to or higher than the predetermined temperature T1. It was supposed to be activated. Further, when the coolant temperature THW in the engine body 2 becomes equal to or higher than the predetermined temperature T1, the water pump 11 is operated in the reverse rotation. As a result, the cooling water circulates in the order of the head-side water jacket 14 and the block-side water jacket 13. First, while the water pump 11 is stopped with respect to the cylinder bore formed in the cylinder block 3. In the cylinder head 4, the cooling water which has already been heated and becomes high temperature flows in. As a result, compared with the case where the water pump 11 is operated in the normal rotation, the high-temperature cooling water can be caused to flow in the vicinity of the cylinder bore of the block-side water jacket 13, and the occurrence of a rapid temperature drop of the cylinder bore can be suppressed. Can do. Therefore, without increasing the weight of the cylinder bore, it is possible to suppress a decrease in the durability of the cylinder bore due to a rapid temperature drop of the cylinder bore, and to improve the fuel consumption of the engine 1.

(2) The water pump 11 is an electric pump. Thereby, the structure which operates the water pump 11 by reverse rotation can be easily realized.
(3) The water pump 11 is such that the minimum discharge flow rate of the cooling water at the time of reverse rotation is smaller than that at the time of the normal rotation, and the cooling water temperature THW inside the engine body 2 becomes equal to or higher than the predetermined temperature T1, and the water pump 11 is reversed. When operating by rotation, the discharge flow rate by the water pump 11 is set to the minimum discharge flow rate during reverse rotation.

  By operating the water pump 11 in the reverse rotation, all of the cooling water already heated in the cylinder head 4 and having a high temperature while the water pump 11 is in a stopped state is cylinder bore of the block-side water jacket 13. After flowing out from the vicinity, cooling water still at a low temperature outside the engine body 2 flows into the engine body 2 thereafter. Therefore, even if the water pump 11 is operated in the reverse rotation, when the discharge rate of the cooling water by the water pump 11 is made relatively large, such low-temperature cooling water is discharged from the cylinder head 4 in the head-side water jacket 14. Before being heated by this heat, it flows into the block-side water jacket 13 and there is a possibility that the deterioration of the durability of the cylinder bore due to the rapid temperature drop of the cylinder bore cannot be suppressed accurately.

On the other hand, in some electric pumps, the minimum discharge flow rate of cooling water during reverse rotation is smaller than during normal rotation.
According to the above embodiment, when the water pump 11 is operated in reverse rotation, the cooling water discharge flow rate by the water pump 11 becomes the smallest. As a result, it is possible to lengthen the period during which the low-temperature cooling water that has flowed into the head-side water jacket 14 from the outside of the engine body 2 exists in the water jacket 14, that is, the period during which it is heated by the heat of the cylinder head 4. Accordingly, the temperature THW of the cooling water flowing in the vicinity of the cylinder bore in the block-side water jacket 13 can be maintained high, and the deterioration of the durability of the cylinder bore due to the sudden temperature drop of the cylinder bore can be appropriately suppressed. become.

  (4) When the coolant temperature THW in the engine body 2 becomes equal to or higher than the reference temperature T2 (> T1) higher than the predetermined temperature T1, the water pump 11 is operated in the normal rotation. As a result, it is possible to allow cooler cooling water to flow into the block-side water jacket 13 and to increase the temperature of the cylinder bore excessively as compared with the configuration in which the water pump 11 is continuously operated in the reverse rotation. Can be suppressed.

  Note that the engine control apparatus according to the present invention is not limited to the configuration exemplified in the above embodiment, and can be implemented as, for example, the following forms appropriately modified.

  In the above embodiment, the predetermined temperature T1 is set to 70 ° C. based on the experimental results using the engine 1, but the predetermined temperature according to the present invention is not limited to this, and the present invention is applicable. The predetermined temperature may be set to a temperature higher than 70 ° C. or a temperature lower than 70 ° C. according to the temperature characteristics of the engine, more specifically, the engine main body.

  In the above embodiment, the reference temperature T2 is set to 90 ° C. based on the experimental results using the engine 1, but the reference temperature according to the present invention is not limited to this and is higher than the predetermined temperature. If the temperature is high, the reference temperature may be set higher than 90 ° C. or lower than 90 ° C. according to the temperature characteristics of the engine to which the present invention is applied, more specifically, the engine body. The temperature may be set.

  In the above embodiment, when the coolant temperature THW is equal to or higher than the reference temperature higher than the predetermined temperature, the water pump 11 is operated in the normal rotation, but the condition for switching the water pump from the reverse rotation to the normal rotation Is not limited to this. In addition, for example, when the reference time has elapsed since the water pump 11 is operated in the reverse rotation, the water pump 11 may be operated in the normal rotation. Even in this case, as compared with the case where the water pump 11 is continuously operated in the reverse rotation, cooler cooling water can be caused to flow in the vicinity of the cylinder bore in the cooling water passage, and the temperature of the cylinder bore is excessively increased. It is possible to accurately suppress this.

  As in the above embodiment, it is desirable to set the discharge flow rate by the water pump 11 during reverse rotation to the minimum discharge flow rate. However, the discharge flow rate by the water pump 11 at the time of reverse rotation is not limited to this. For example, it is set to a value that is larger than the minimum discharge flow rate at the time of reverse rotation but smaller than the minimum discharge flow rate at the time of forward rotation. If so, the discharge flow rate of the cooling water during the reverse rotation can be accurately set to be small.

  In the above-described embodiment, the water pump 11 in which the minimum discharge flow rate of the cooling water at the time of reverse rotation is smaller than that at the time of normal rotation is adopted, but the water pump according to the present invention is not limited to this. The minimum discharge flow rate may be the same during rotation and reverse rotation.

  -As above-mentioned embodiment, it is desirable to make a water pump into an electric pump from the viewpoint of implement | achieving the structure which operates a water pump by reverse rotation easily. However, the water pump according to the present invention is not limited to an electric pump, and can be realized by a mechanical pump. In this case, in this case, a mechanism for switching transmission / disconnection of the driving force between the output shaft of the engine 1 and the output shaft of the pump, and the driving force from the output shaft of the engine 1 are transmitted to the output shaft of the pump. What is necessary is just to provide the mechanism which switches the transmission direction at the time of doing.

  DESCRIPTION OF SYMBOLS 1,101 ... Engine, 2,102 ... Engine main body, 3, 103 ... Cylinder block, 3a ... Cylinder bore, 4,104 ... Cylinder head, 10, 110 ... Cooling water passage, 11, 111 ... Water pump, 13, 113 ... Block side water jacket, 14, 114 ... Head side water jacket, 15, 115 ... Main passage, 16, 116 ... Radiator, 17, 117 ... Detour passage, 18, 118 ... Thermostat, 20 ... Electronic control unit, 21 ... Water temperature sensor 22 ... Ignition switch.

Claims (6)

Applied to an engine having a cooling water circulation system in which cooling water circulates through a cooling water passage in the order of a cylinder block and a cylinder head constituting the engine body at the time of forward rotation of the water pump, and the temperature of the cooling water inside the engine body is a predetermined temperature. A control device for the engine that operates the water pump when the temperature of the cooling water in the engine body is equal to or higher than the predetermined temperature, while the water pump is stopped when lower than
The engine control device, wherein when the temperature of the cooling water inside the engine body becomes equal to or higher than the predetermined temperature, the water pump is operated in reverse rotation. The engine control device according to claim 1,
The engine control device, wherein the water pump is an electric pump. The engine control device according to claim 2,
The water pump is such that the minimum discharge flow rate of cooling water during reverse rotation is smaller than during normal rotation,
When the temperature of the cooling water inside the engine body becomes equal to or higher than the predetermined temperature and the water pump is operated in reverse rotation, the discharge flow rate by the water pump is made smaller than the minimum discharge flow rate during normal rotation. Engine control device. The engine control device according to claim 3,
When the temperature of the cooling water inside the engine body becomes equal to or higher than the predetermined temperature and the water pump is operated in reverse rotation, the discharge flow rate by the water pump is set as the minimum discharge flow rate in reverse rotation. Engine control device. In the engine control apparatus according to any one of claims 1 to 4,
The engine control device, wherein when the temperature of the cooling water inside the engine body becomes equal to or higher than a reference temperature higher than the predetermined temperature, the water pump is operated in a normal rotation. In the engine control apparatus according to any one of claims 1 to 4,
An engine control device, wherein when the reference time has elapsed since the water pump was operated in reverse rotation, the water pump is operated in forward rotation.

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