JP2012188988A - Engine cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine cooling device that can miniaturize a radiator or a cooling fan and reduce the amount of cooling water.SOLUTION: The engine cooling device 1 includes: an engine bypass cooling water channel 11 for bypassing between an inlet port and an outlet port; and a bypass on-off unit 15 for not supplying the cooling water to the engine bypass cooling water channel 11 when a temperature of the cooling water in the engine 3 is lower than a threshold, and for supplying the cooling water to the engine bypass cooling water channel 11 when the temperature of the cooling water in the engine 3 is equal to or higher than the threshold.

Description

  The present invention relates to an engine cooling device in which a radiator and a cooling fan can be downsized, and the amount of cooling water is reduced.

  As shown in FIG. 3, the conventional engine cooling device 31 is connected to the discharge port of the water pump 2 and branched through the engine cooling water channel 4 passing through the engine 3 and the discharge port of the water pump 2. An EGR system cooling water path 6 that joins the engine system cooling water path 4 downstream of the engine 3 via the cooler 5, and a water heater that is connected to the merging end of the engine cooling water path 4 and the EGR cooling water path 6 via the radiator 7. A radiator-type cooling water passage 8 reaching the suction port of the pump 2 is provided.

  A radiator thermostat 9 is installed between the radiator 7 and the water pump 2 in the radiator cooling water channel 8, and a radiator bypass cooling water channel 10 that bypasses the radiator 7 is installed between the inlet of the radiator 7 and the radiator thermostat 9. .

  The engine 3 is formed with a water jacket in which cooling water is circulated within the wall thickness of the cylinder head and the cylinder block.

  The EGR cooler 5 has a structure in which cooling water is introduced around a thin tube through which EGR gas passes, or a structure in which EGR gas passes through a thin tube through which cooling water is introduced.

  In the engine cooling device 31, the cooling water pumped by the water pump 2 branches and flows into the engine cooling water channel 4 and the EGR cooling water channel 6. The cooling water exchanges heat with the engine 3 through the water jacket of the engine 3. The cooling water exchanges heat with the EGR gas in the EGR cooler 5.

  The cooling water received by the engine 3 and the EGR cooler 5 is cooled by exchanging heat with the atmosphere in the radiator 7 and returns to the water pump 2. The cooling water thus cooled is again pumped by the water pump 2 and flows to the engine 3 and the EGR cooler 5.

  When the cooling water temperature is equal to or lower than the switching temperature of the radiator thermostat 9 as in the cold start, the cooling water coming out of the engine 3 and the EGR cooler 5 does not go to the radiator 7 but passes through the radiator bypass cooling water passage 10 and the radiator thermostat. Return from 9 to the water pump 2. Thereby, cooling water warms up early and warm-up is accelerated | stimulated. Since the cooling water temperature exceeds the switching temperature of the radiator thermostat 9 after the warm-up is achieved, the cooling water that has come out of the engine 3 and the EGR cooler 5 passes through the radiator 7 without being bypassed and passes from the radiator thermostat 9 to the water pump 2. Return. As a result, the high-temperature cooling water is dissipated by the radiator 7.

JP 2009-250147 A

  In the engine cooling device 31, since the additive is added to the cooling water and the cooling water is pressurized to a pressure higher than the atmospheric pressure, the boiling point of the cooling water is higher than 105 ° C. Boiling is less likely to occur than water with no additives at normal pressure. However, if the cooling water is boiled, steam will be ejected from the radiator 7, which is not preferable. In addition, if local boiling occurs in the EGR cooler 5, the EGR cooler 5 is damaged. Therefore, it is important to prevent boiling so that the cooling water does not boil even for a moment.

  In order to prevent such boiling, the engine cooling device 31 is configured such that the cooling water temperature does not exceed a reference temperature (for example, 100 ° C. to 105 ° C.). Specifically, it is required that the cooling water temperature does not exceed the reference temperature even in a disadvantageous state of cooling, such as when the engine is heavily loaded due to a steep climb when the outside air temperature is high, such as during the daytime in summer.

  For this reason, conventionally, the radiator 7 and the cooling fan (not shown) of the radiator 7 are large-sized ones with sufficient cooling capacity.

  However, since a large amount of energy is consumed in order to drive a large cooling fan, fuel efficiency is deteriorated. In addition, since the large radiator 7 and the large cooling fan are heavy, the weight of the vehicle increases and the fuel consumption decreases.

  Furthermore, when the radiator 7 becomes large, the amount of cooling water filled in the engine cooling device 31 increases. For this reason, while the cooling water cost becomes high and the amount of circulating cooling water increases, the work amount of the water pump 2 increases, and the fuel efficiency deteriorates.

  Accordingly, an object of the present invention is to provide an engine cooling apparatus that solves the above-described problems, enables a radiator and a cooling fan to be miniaturized, and reduces the amount of cooling water.

  In order to achieve the above object, an engine cooling device of the present invention includes an engine cooling water passage that is connected to a discharge port of a water pump and passes through the engine, and a branch connection that is connected to the discharge port of the water pump and passes through an EGR cooler. An EGR system cooling water channel that merges with the engine cooling water channel downstream from the engine, and a radiator system that is connected to the merging end of the engine cooling water channel and the EGR cooling water channel and reaches the suction port of the water pump via the radiator In the engine cooling device comprising a cooling water channel, the engine bypass cooling water channel that bypasses between the inlet and outlet of the engine, and when the cooling water temperature in the engine is less than a threshold value, the engine bypass cooling water channel does not pass the cooling water, Cooling to the engine bypass cooling water channel when the cooling water temperature in the engine is above the threshold Those having a bypass switching means passing.

  The bypass opening / closing means shuts off the bypass valve when a bypass valve installed in the engine bypass cooling water channel, a water temperature sensor for detecting a cooling water temperature in the engine, and a cooling water temperature detected by the water temperature sensor is less than a threshold value. And a controller that opens the bypass valve when a coolant temperature detected by the water temperature sensor is equal to or higher than a threshold value.

  The bypass opening / closing means may be provided in the engine bypass cooling water channel, and may include an engine bypass thermostat that is closed when the cooling water temperature is lower than a threshold and opened when the cooling water temperature is equal to or higher than the threshold.

  The present invention exhibits the following excellent effects.

  (1) The radiator and the cooling fan can be downsized.

  (2) The amount of circulating cooling water is reduced.

It is a cooling circuit diagram of the engine cooling device showing one embodiment of the present invention. It is a cooling circuit diagram of the engine cooling device which shows other embodiment of this invention. It is a cooling circuit diagram of the conventional engine cooling device.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, an engine cooling apparatus 1 according to the present invention is branched and connected to an engine system cooling water passage 4 connected to a discharge port of a water pump 2 and passing through an engine 3 and a discharge port of the water pump 2. The EGR system 6 is connected to the engine system cooling water channel 6 downstream of the engine 3 via the EGR cooler 5, and the merging end of the engine cooling channel 4 and the EGR cooling water channel 6. A radiator-type cooling water passage 8 reaching the suction port of the water pump 2 is provided.

  In the radiator cooling water passage 8, a radiator thermostat 9 is installed between the radiator 7 and the water pump 2, and a radiator bypass cooling water passage 10 that bypasses the radiator 7 between the inlet of the radiator 7 and the radiator thermostat 9 is installed. Is done.

  In this embodiment, the engine cooling device 1 includes an engine bypass cooling water channel 11 that bypasses between the inlet and outlet of the engine 3, a bypass valve 12 installed in the engine bypass cooling water channel 11, and a water temperature that detects a cooling water temperature in the engine 3. The sensor 13 includes a control unit 14 that shuts off the bypass valve 12 when the coolant temperature detected by the water temperature sensor 13 is less than the threshold value, and opens the bypass valve 12 when the coolant temperature detected by the water temperature sensor 13 is equal to or greater than the threshold value.

  The bypass valve 12, the water temperature sensor 13, and the control unit 14 do not pass the cooling water through the engine bypass cooling water channel 11 when the cooling water temperature in the engine 3 is lower than the threshold value, and the engine bypass cooling water channel when the cooling water temperature in the engine 3 is equal to or higher than the threshold value. A bypass opening / closing means 15 for passing cooling water through 11 is configured.

  The internal structure and pumping system of the water pump 2 are not limited to specific ones, but the water pump 2 has a low flow rate (flow velocity) of cooling water to be pumped and a low load resistance on the discharge side when the load resistance on the discharge side is high. And the flow rate (flow velocity) of the cooling water to be pumped increases. The flow rate adjustment by opening / closing the bypass valve 12 utilizes this characteristic.

  The bypass valve 12 may be an on / off valve capable of controlling two states of fully closed and partially throttled (or fully opened), or an opening degree adjusting valve capable of continuously variable control from fully closed to fully opened. In the case of an on / off valve, the valve is configured so that the opening degree in the partially throttled (or fully opened) state becomes a set value. In the case of an opening adjustment valve, the opening is set in the control unit 14.

  The opening is preferably set as follows. Due to the characteristics of the water pump 2, the amount of cooling water pumped by the water pump 2 when the bypass valve 12 is opened is larger than the amount of cooling water pumped by the water pump 2 when the bypass valve 12 is shut off. On the other hand, when the bypass valve 12 is opened, the amount of cooling water flowing through the engine 3 and the engine bypass cooling water channel 11 is determined by the pumping capacity of the water pump 2, the load resistance of the engine bypass cooling water channel 11 including the bypass valve 12, and the load of the engine 3. Determined by the balance of resistance. The degree of opening of the bypass valve 12 through experiments or the like so that the amount of cooling water flowing to the engine 3 when the bypass valve 12 is opened is reduced by about 1/20 to 1/10 of the amount of cooling water flowing to the engine 3 when the bypass valve 12 is shut off. Is set.

  The water temperature sensor 13 is installed at the outlet of the engine 3. When the water temperature sensor 13 is installed at the outlet of the engine 3, it is suitable for determining whether or not the cooling water is about to reach the reference temperature described in the column of the problem in the engine 3. The threshold value of the cooling water temperature is preferably a reference temperature or a temperature slightly lower than the reference temperature.

  The control unit 14 is preferably installed as software in an electronic control unit (ECU).

  Hereinafter, the operation of the engine cooling device 1 will be described.

  When the cooling water is lower than the reference temperature in the engine 3, the cooling water does not boil. Therefore, the control unit 14 blocks the bypass valve 12 when the cooling water temperature detected by the water temperature sensor 13 is lower than the threshold value set lower than the reference temperature. Thereby, the cooling water pumped by the water pump 2 flows into the engine system cooling water channel 4 and the EGR system cooling water channel 6, merges, and flows into the radiator system cooling water channel 8. Needless to say, the entire amount of the cooling water flowing into the engine system cooling water passage 4 passes through the engine 3 at this time. When the cooling water temperature is equal to or lower than the switching temperature of the radiator thermostat 9, the cooling water passes through the radiator bypass cooling water channel 10.

  When the engine 3 continues to be in a high load state, the coolant temperature rises. When the cooling water in the engine 3 becomes a high temperature close to the reference temperature, it is necessary to prevent boiling. The controller 14 opens the bypass valve 12 when the cooling water temperature detected by the water temperature sensor 13 is equal to or higher than the threshold value. When the bypass valve 12 is opened, the cooling water pumped by the water pump 2 is divided into the engine system cooling water channel 4 and the EGR system cooling water channel 6, and the engine 3 and the engine bypass cooling water channel 11 in the engine system cooling water channel 4. It is divided into and flows. After the cooling water that has flowed through the engine 3 and the engine bypass cooling water channel 11 merges, the cooling water further merges with the cooling water in the EGR cooling water channel 6 and flows into the radiator cooling water channel 8.

  In the engine 3, the amount of cooling water flowing in is about 1/20 to 1/10 less than when the bypass valve 12 is shut off. As will be described later, when the bypass valve 12 is opened, the amount of cooling water pumped by the water pump 2 increases, but a part of the cooling water flowing into the engine system cooling water channel 4 does not flow into the engine 3. This is because it flows into the engine bypass cooling water channel 11. Thus, since the amount of cooling water passing through the engine 3 decreases, the temperature of the engine 3 itself increases. However, the cylinder head and the cylinder block constituting the engine 3 do not immediately cause a problem even if the temperature rises temporarily. Since the amount of cooling water passing through the engine 3 is reduced, the amount of heat received by the cooling water from the engine 3 is reduced. As a result, the amount of heat carried by the cooling water to the radiator 7 is reduced, and the cooling water temperature in the radiator 7 is lowered.

  On the other hand, in the water pump 2, since the destination of the cooling water discharged from the water pump 2 is increased as compared with that before the bypass valve 12 is opened, the load resistance against the force to be discharged becomes light and the cooling water to be pumped is sent. The flow rate (flow velocity) increases. Specifically, since the engine bypass cooling water channel 11 is added in parallel with the engine 3, the amount of cooling water flowing into the engine system cooling water channel 4 increases. Therefore, the total amount of cooling water flowing through the engine system cooling water channel 4 and the EGR system cooling water channel 6 increases. For this reason, the flow volume of the cooling water which flows into the radiator type cooling water channel 8 increases compared with before the bypass valve 12 is opened.

  Since the flow rate of the cooling water that passes through the radiator 7 has increased, the amount of cooling water that returns to the water pump 2 increases. A part of the cooling water returned to the water pump 2 flows into the radiator cooling water passage 8 without receiving heat through the engine bypass cooling water passage 11 having no heat source. Thereby, the temperature of the cooling water flowing into the radiator 7 is lowered. Since this cooling water is cooled by the radiator 7, the cooling water temperature that passes through the radiator 7 and returns to the water pump 2 is lower than before the bypass valve 12 is opened.

  In this way, a part of the cooling water circulated in the engine cooling device 1 is re-cooled by the radiator 7 without receiving heat, so that the whole cooling water becomes low temperature, and this cooling water flows into the engine 3. The cooling water temperature at the outlet of the engine 3 also decreases. The cooling water flowing into the EGR cooler 5 is also low in temperature. Thereby, boiling of cooling water is prevented beforehand.

  When the cooling water temperature detected by the water temperature sensor 13 returns below the threshold value, the control unit 14 blocks the bypass valve 12. Thereby, since the amount of cooling water passing through the engine 3 increases, the amount of heat received by the cooling water from the engine 3 increases. However, since the cooling water temperature is lowered while the bypass valve 12 is open, the engine 3 is well cooled. Even if the engine 3 is continuously in a high load state, the cooling water temperature does not immediately exceed the threshold value. In the engine 3, a high load state in which the cooling water temperature approaches the boiling point rarely continues for a long time. If it is necessary to prevent hunting of the bypass valve shut-off / opening when the high load state continues for a long time, it is preferable to provide hysteresis to the threshold value of the cooling water temperature determined by the control unit 14.

  As described above, according to the engine cooling device 1 according to the present invention, the bypass valve 12 is opened when the cooling water temperature is equal to or higher than the threshold value. Therefore, when the cooling water temperature approaches the boiling point, the engine bypass cooling water channel 11 is opened. The cooling water flows through the radiator 7 and the cooling water is efficiently cooled, and the boiling of the cooling water in the engine 3 and the EGR cooler 5 is prevented in advance. As a result, it is possible to reduce the size of the radiator 7 and the cooling fan that are conventionally required to be large for preventing boiling, and the cooling water cost is reduced by reducing the amount of cooling water.

  In the engine cooling device 1 of FIG. 1, since the water temperature sensor 13 detects the cooling water temperature, the accuracy of the cooling water temperature is high, and the bypass valve 12 is shut off and opened by electronic control from the control unit 14, so that the responsiveness is good. Therefore, if a threshold value is set based on experiments or the like, the cooling water temperature can be prevented from exceeding the boiling point even for a moment, and boiling of the cooling water is reliably prevented.

  In the embodiment of FIG. 1, the bypass opening / closing means 15 is configured by the bypass valve 12, the water temperature sensor 13, and the control unit 14, but the bypass opening / closing means 15 may be configured by a thermostat different from the radiator thermostat 9.

  As shown in FIG. 2, similarly to the engine cooling device 1, the engine cooling device 21 is connected to the discharge port of the water pump 2 and passes through the engine 3, and the discharge port of the water pump 2. The EGR system cooling water channel 6 is joined to the engine system cooling water channel 4 downstream of the engine 3 via the EGR cooler 5 and connected to the merging end of the engine cooling water channel 4 and the EGR cooling water channel 6 to the radiator 7. A radiator-type cooling water channel 8 that reaches the suction port of the water pump 2 via the engine, an engine bypass cooling water channel 11 that bypasses between the inlet and outlet of the engine 3, and an engine bypass cooling water channel 11 when the cooling water temperature in the engine 3 is lower than the threshold value. When the cooling water temperature in the engine 3 is equal to or higher than the threshold value, the cooling water is passed through the engine bypass cooling water passage 11. And a bypass switching means 15.

  The bypass opening / closing means 15 includes an engine bypass thermostat 16 that is installed in the engine bypass cooling water channel 11 and is closed when the cooling water temperature is lower than the threshold and opened when the cooling water temperature is equal to or higher than the threshold.

  The engine bypass thermostat 16 is designed so that the amount of cooling water flowing to the engine 3 when the engine bypass thermostat 16 is opened is about 1/20 to 1/10 of the amount of cooling water flowing to the engine 3 when the engine bypass thermostat 16 is shut off. Etc., the opening degree of the passage is set.

  The operation of the bypass opening / closing means 15 in the engine cooling device 21 is the same as that in the case of the engine cooling device 1, thereby preventing boiling of the cooling water in the engine 3 and the EGR cooler 5.

  Note that the control with a thermostat has a large variation in accuracy and responsiveness to temperature compared to electronic control using a water temperature sensor, so that the threshold is sufficiently marginal than the boiling point to reliably prevent boiling of cooling water. It is desirable to set a certain low temperature.

DESCRIPTION OF SYMBOLS 1,21 Engine cooling device 2 Water pump 3 Engine 4 Engine system cooling water channel 5 EGR cooler 6 EGR system cooling water channel 7 Radiator 8 Radiator system cooling water channel 9 Radiator thermostat 10 Radiator bypass cooling water channel 11 Engine bypass cooling water channel 12 Bypass valve 13 Water temperature sensor 14 Control unit 15 Bypass opening / closing means 16 Engine bypass thermostat

Claims (3)

An engine cooling water passage connected to the discharge port of the water pump and passing through the engine;
An EGR system cooling water channel that is branched and connected to the discharge port of the water pump and joins the engine cooling water channel downstream of the engine via an EGR cooler;
An engine cooling device comprising: a radiator cooling water passage connected to a confluence end of the engine cooling water passage and the EGR cooling water passage and reaching a suction port of the water pump via a radiator;
An engine bypass cooling water passage that bypasses between the inlet and outlet of the engine;
A bypass opening / closing means for not passing cooling water through the engine bypass cooling water passage when the cooling water temperature in the engine is lower than a threshold, and passing cooling water through the engine bypass cooling water passage when the cooling water temperature in the engine is equal to or higher than the threshold; An engine cooling device characterized by that. The bypass opening / closing means includes
A bypass valve installed in the engine bypass cooling water channel;
A water temperature sensor for detecting a cooling water temperature in the engine;
A control unit that shuts off the bypass valve when a cooling water temperature detected by the water temperature sensor is lower than a threshold value and opens the bypass valve when the cooling water temperature detected by the water temperature sensor is equal to or higher than the threshold value. The engine cooling device according to claim 1. The bypass opening / closing means includes
2. The engine cooling apparatus according to claim 1, further comprising an engine bypass thermostat that is installed in the engine bypass cooling water channel and is closed when the cooling water temperature is lower than a threshold value and opened when the cooling water temperature is equal to or higher than the threshold value.

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