JP2018193963A - Cooling device for internal combustion engine - Google Patents

Abstract

A cooling device for an internal combustion engine capable of reliably preventing knocking by ensuring a desired cooling performance for a cylinder head. An internal combustion engine cooling device X includes a pump P that circulates cooling water to the internal combustion engine E, and a first flow path that is a path through which cooling water circulates between a cylinder head Ea and a radiator 3 by a driving force of the pump P. 11, the thermostat valve 4 disposed in the first flow path 11, and the first flow path 11 downstream of the cylinder head Ea and upstream of the radiator 3 and the thermostat valve 4, and from the radiator 3 and the thermostat valve 4. A second flow path 12 that bypasses the downstream side and passes through the cylinder block Eb, an electromagnetic valve V disposed in the second flow path 12, and a control unit 5 that controls opening and closing of the electromagnetic valve V. ing. [Selection] Figure 1

Description

  The present invention relates to a cooling device for an internal combustion engine that cools the internal combustion engine with cooling water.

  2. Description of the Related Art Conventionally, a cooling device for an internal combustion engine that circulates cooling water through an internal combustion engine by a driving force of a mechanical water pump that changes the discharge amount of the cooling water according to the rotational speed of the internal combustion engine is known (for example, Patent Documents). 1).

  A cooling device for an internal combustion engine described in Patent Document 1 includes a radiator passage through which cooling water circulates in the order of a cylinder head, a radiator, a thermostat valve, and a cylinder head, and a cylinder head, a cylinder block, a thermostat valve, and a cylinder head in this order. And a block channel through which cooling water circulates. The thermostat valve includes a valve body that opens the radiator flow path when the temperature of the cooling water is equal to or higher than a first predetermined temperature, and a temperature equal to or higher than a second predetermined temperature that is higher than the first predetermined temperature. And a valve body that further opens the block flow path. Accordingly, it is described that the block flow path is opened when the cooling water is at a high temperature, so that it is possible to prevent the temperature of the cylinder block from being rapidly lowered.

JP 2012-184893 A

  In the cooling device for an internal combustion engine described in Patent Document 1, since the temperature of the cylinder head adjacent to the combustion chamber continues to rise until the radiator flow path is opened, knocking due to abnormal combustion of fuel may occur. . In addition, since a radiator used in an automobile needs to exchange heat with ambient air in a limited space, the surface area of the flow path is secured by meandering or branching a plurality of thin tubes. For this reason, even when the flow path resistance of the radiator is large and the radiator flow path is opened, there is a possibility that a desired amount of cooling water for preventing the occurrence of knocking does not flow to the cylinder head.

  Furthermore, after opening the block flow path, the temperature of the cooling water rises due to the heat transfer from the cylinder block and the amount of cooling water flowing through the radiator flow path, so it is difficult to exhibit the desired cooling performance for the cylinder head. There is a risk of knocking.

  Thus, a cooling device for an internal combustion engine that can reliably prevent knocking by ensuring a desired cooling performance for the cylinder head is desired.

  A characteristic configuration of the cooling device for the internal combustion engine includes a pump for circulating cooling water to the internal combustion engine, a first flow path that is a path for circulating the cooling water to the cylinder head and the radiator by the driving force of the pump, and the first flow Bypassing the thermostat valve arranged in the passage, the first flow path downstream of the cylinder head, upstream of the radiator and the thermostat valve, and downstream of the radiator and the thermostat valve In addition, a second flow path that passes through the cylinder block, an electromagnetic valve disposed in the second flow path, and a control unit that controls opening and closing of the electromagnetic valve are provided.

  In this configuration, a thermostat valve is disposed in the first flow path through which the coolant circulates between the cylinder head and the radiator, and the second flow path passes through the cylinder block without passing through the radiator and the thermostat valve as the bypass flow path of the first flow path. A flow path is provided, and an electromagnetic valve is disposed in the second flow path. That is, no thermostat valve exists in the flow path from the cylinder head through the cylinder block, and an electromagnetic valve that can be controlled to open and close regardless of the temperature of the cooling water is disposed.

  For this reason, if the solenoid valve is opened in a situation where the cooling water is at a low temperature and the thermostat valve is not opened, the amount of cooling water flowing to the cylinder head via the second flow path can be increased. As a result, engine combustion temperature can be lowered to prevent knocking. Moreover, warm-up can be promoted by circulating cooling water through the cylinder block in addition to the cylinder head.

  On the other hand, after the thermostat valve is opened, even if the coolant flow rate of the radiator causes a sufficient amount of cooling water for the cylinder head, if the solenoid valve is opened, the cylinder block has a relatively low flow rate resistance. Since water can flow, the amount of cooling water for the cylinder head can be increased. Thus, the cooling device of the internal combustion engine which can prevent knocking reliably by ensuring the desired cooling performance for the cylinder head can be provided.

  Another configuration is that the control unit adjusts the opening degree of the electromagnetic valve so as to increase a flow rate of the cooling water flowing through the cylinder head when a knocking condition of the internal combustion engine is satisfied. .

  In this configuration, when the knocking condition of the internal combustion engine is satisfied, the opening of the electromagnetic valve is adjusted to increase the amount of cooling water flowing through the cylinder head, so that knocking can be prevented. In addition, the highly responsive configuration of adjusting the opening of the solenoid valve can quickly increase the amount of cooling water when the knocking condition is satisfied.

  Another configuration is that the knocking condition is satisfied when the temperature is lower than the temperature at which the thermostat valve opens and the high load condition of the internal combustion engine is satisfied.

  Even when the cooling water is at a low temperature, knocking may occur under a high load condition, for example, starting on a slope, under a condition where the amount of cooling water with respect to the cylinder head is small. Therefore, as in this configuration, when the temperature of the thermostat valve is below the opening temperature and the high load condition of the internal combustion engine is satisfied, the amount of cooling water flowing to the cylinder head is increased by adjusting the opening of the solenoid valve. By doing so, knocking can be prevented.

  In another configuration, the pump is configured to generate a driving force in proportion to the rotational speed of the internal combustion engine, and when the knocking condition is satisfied, after the thermostat valve is opened, This is when the rotational speed of the internal combustion engine is not more than a predetermined value and the high load condition of the internal combustion engine is satisfied.

  In this configuration, the pump is composed of a mechanical pump that generates a driving force in accordance with the rotational speed of the internal combustion engine. Therefore, even after the thermostat valve is opened, the cooling to the cylinder head is performed when the rotational speed is low. The amount of water is small. When the load of the internal combustion engine becomes high in this state, the combustion temperature of the engine increases and knocking is likely to occur. Therefore, as in this configuration, after the thermostat valve is opened, when the rotational speed of the internal combustion engine is not more than a predetermined value and the high load condition of the internal combustion engine is satisfied, the opening degree of the electromagnetic valve is adjusted to Knocking can be prevented by increasing the flow rate of the cooling water to the block.

It is a block diagram of the cooling device of an internal combustion engine. It is a control flowchart of a solenoid valve. It is a figure which shows the flow volume characteristic of the cooling device of an internal combustion engine.

  Hereinafter, an embodiment of a cooling apparatus for an internal combustion engine according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the invention.

[Basic configuration]
As shown in FIG. 1, a cooling device X for an internal combustion engine includes an engine E as an internal combustion engine, a pump P that circulates cooling water (coolant) in the engine E, a heater core H that generates warm air in the vehicle, and an ATF. An oil cooler 1 that cools oil, an EGR cooler 2, a radiator 3, a thermostat valve 4, a solenoid valve V that can be adjusted by the driving force of an electric motor, and a control that controls opening and closing of the solenoid valve V Part 5.

  The engine E has a cylinder head Ea adjacent to a combustion chamber (not shown) and a cylinder block Eb that houses a piston (not shown). Further, a shaft sensor Sb for detecting the rotational speed of the engine E is provided in the vicinity of the crankshaft (not shown) of the engine E. Further, an intake manifold (not shown) of the engine E is provided with an intake air temperature sensor Sc, an intake pressure sensor Sd, and an air flow meter Se for detecting the intake air amount.

  The pump P is composed of a mechanical water pump that rotates in conjunction with the rotation of the crankshaft of the engine E. In addition, you may comprise the pump P with the electric water pump rotated by the driving force of an electric motor.

  The thermostat valve 4 maintains a valve closed state when the coolant temperature is lower than a set temperature (for example, 80 to 90 ° C.), and switches to a valve open state when the water temperature is equal to or higher than the set temperature. It is a mold on-off valve. Hereinafter, the temperature of the cooling water that opens the thermostat valve 4 is referred to as “set temperature”.

  The control unit 5 is configured as an ECU (engine control unit), and the rotation speed of the engine E obtained from the shaft sensor Sb, the intake air temperature measured by the intake air temperature sensor Sc, and the intake air measured by the intake pressure sensor Sd. The opening and closing of the solenoid valve V is controlled based on the engine load (filling efficiency and the like) calculated from the pressure and the intake air amount measured by the air flow meter Se.

  The cooling device X for the internal combustion engine branches from the downstream side of the cylinder head Ea of the first flow path 11 and the first flow path 11 in which the cooling water circulates to the cylinder head Ea and the radiator 3 by the driving force of the pump P. A second flow path 12 and a third flow path 13 and a fourth flow path 14 branched from the downstream side of the second flow path 12 in the first flow path 11 are provided.

  In the first flow path 11, a pump P, a cylinder head Ea, a radiator 3, and a thermostat valve 4 are sequentially arranged along the flow direction of the cooling water. A water temperature sensor Sa for measuring the coolant temperature is provided on the outlet side of the cylinder head Ea in the first flow path 11. The pump P may be provided on the outlet side of the cylinder head Ea.

  In the second flow path 12, an electromagnetic valve V and a cylinder block Eb are sequentially arranged along the flow direction of the cooling water. Note that the solenoid valve V may be disposed on the downstream side of the cylinder block Eb. This second flow path 12 bypasses the first flow path 11 downstream of the cylinder head Ea, upstream of the radiator 3 and the thermostat valve 4, and downstream of the radiator 3 and the thermostat valve 4. Further, it is configured to pass through the cylinder block Eb.

  A heater core H is disposed in the third flow path 13, an oil cooler 1 and an EGR cooler 2 are disposed in the fourth flow path 14, and a combined flow path 15 of the third flow path 13 and the fourth flow path 14. Is connected to the downstream side of the thermostat valve 4. The combined flow path 15 may be connected to the thermostat valve 4 in a form that bypasses the valve body of the thermostat valve 4. Moreover, the heat exchanger arrange | positioned at the 3rd flow path 13 or the 4th flow path 14 is not limited to the heater core H, the oil cooler 1, and the EGR cooler 2, and any one of these may be sufficient, Other heat exchangers may be arranged and are not particularly limited.

  With such a flow path configuration, the cylinder block Eb, the heater core H, the oil cooler 1 and the EGR cooler 2, the radiator 3 and the thermostat valve 4 are arranged in parallel from the downstream side of the cylinder head Ea of the first flow path 11, respectively. Has been placed.

[Control form]
Hereinafter, an example of the control mode of the cooling device X for the internal combustion engine according to the present embodiment will be described with reference to FIG.

  When the engine E is started, the engine E starts cranking, the pump P is activated, and the cooling water starts to circulate in the first flow path 11. At this time, the solenoid valve V is not energized and is in a closed state (# 21). Further, when the engine E is started, the coolant temperature is low and the thermostat valve 4 is closed. Thus, the cooling water flows through the third flow path 13 and the fourth flow path 14 branched from the first flow path 11 and is heated by the cylinder head Ea. Even when the rotational speed of the engine E reaches the idling rotational speed, the temperature of the cooling water may not reach the temperature at which the thermostat valve 4 is opened. In this case, when the load on the engine E is high, such as when starting on a slope, the temperature of the combustion chamber of the engine E rises due to the fact that the cooling water does not circulate through the radiator 3, and knocking may occur.

  Therefore, in the present embodiment, whether or not the temperature of the cooling water measured by the water temperature sensor Sa (hereinafter referred to as “cooling water temperature”) is equal to or higher than the set temperature and the thermostat valve 4 is opened. The determination is made (# 22).

  When the temperature of the cooling water is lower than the set temperature and the thermostat valve 4 is closed (# 22 NO determination), it is determined whether the high load condition of the engine E is satisfied (# 23). The case where the high load condition is satisfied in the present embodiment is a case where the charging efficiency of the engine E is a predetermined value (for example, 60%) or more. The charging efficiency is calculated based on the intake air temperature measured by the intake air temperature sensor Sc, the intake air pressure measured by the intake air pressure sensor Sd, and the intake air amount measured by the air flow meter Se. The engine load is not limited to the charging efficiency, and may be calculated based on, for example, the throttle valve opening and the torque acting on the crankshaft.

  Here, the flow characteristics of the cooling device X for the internal combustion engine will be described. In FIG. 3, the horizontal axis shows the flow rate of the cooling water flowing through the cylinder head Ea, and the vertical axis shows the pressure loss due to the head pressure of the pump P or the cooling water passing through each flow path 11-14. Has been. Since the pump P in this embodiment is composed of a mechanical water pump, the head pressure of the pump P increases as the rotational speed of the engine E increases as shown by the solid line in FIG. Moreover, when the rotation speed of the engine E is made constant, the head pressure decreases as the discharge flow rate of the pump P increases.

  On the other hand, the curve shown by the dotted line in FIG. 3 shows the pressure loss with respect to the change in the flow rate of the cooling water when the flow paths 11 to 14 through which the cooling water flows change, and the pressure loss increases as the flow rate increases. . (1) is a case where the thermostat valve 4 and the electromagnetic valve V are in a closed state, and the cooling water is a heat exchanger (heater core H, oil cooler) disposed in the third flow path 13 and the fourth flow path 14. 1. It circulates through the heat exchanger path leading to the cylinder head Ea via the EGR cooler 2). (2) is a case where the thermostat valve 4 is fully open and the solenoid valve V is closed. Cooling water is a radiator disposed in the first flow path 11 in addition to the heat exchanger path of (1). 3 circulates through the radiator path reaching the cylinder head Ea. (3) is a case where the electromagnetic valve V is fully open and the thermostat valve 4 is closed, and the cooling water is disposed in the second flow path 12 in addition to the heat exchanger path of (1). A block path is circulated through the cylinder block Eb to the cylinder head Ea. (4) is a case where both the thermostat valve 4 and the electromagnetic valve V are fully open, and the cooling water is the radiator 3 disposed in the first flow path 11, the cylinder block Eb disposed in the second flow path 12, The entire path from the heat exchanger (heater core H, oil cooler 1, EGR cooler 2) disposed in the third flow path 13 and the fourth flow path 14 to the cylinder head Ea is circulated.

  When the heat exchanger path (1) is changed to the heat exchange path + radiator path (2), the cooling water also flows through the first flow path 11 in which the radiator 3 is disposed, so that the total flow path area increases. Thus, the gradient of the pressure loss with respect to the flow rate becomes gentle. In addition, when the heat exchanger path of (1) is changed to the heat exchange path + block path of (3), the cooling water also flows through the second flow path 12 in which the cylinder block Eb is disposed. The total path area increases, and the gradient of pressure loss with respect to the flow rate becomes gentle. In particular, the gradient in the heat exchange path + block path in (3) is more gradual than in the heat exchange path + radiator path in (2). Since the radiator 3 is a device that exchanges heat with ambient air in a limited space, the surface area of the flow path is secured by meandering or branching a plurality of thin tubes, and the flow of the radiator 3 This is because the road resistance is larger than the flow path resistance of the cylinder block Eb. This is also clear from the fact that the gradient does not change so much when the radiator 3 is opened from the heat exchange path + block path of (3) to the entire path of (4).

  The point where the lift pressure curve of the pump P indicated by the solid line in FIG. 3 and the pressure loss curve of the cooling water indicated by the dotted line in FIG. 3 flow into the flow rate of the cooling water actually discharged by the pump P, that is, the cylinder head Ea. It becomes the flow rate of cooling water. As shown at each intersection in FIG. 3, when the rotational speed of the engine E is constant, the electromagnetic valve V in (3) is in a fully open state rather than the thermostat valve 4 in (2) is in a fully open state. However, the flow rate of the cooling water flowing through the cylinder head Ea can be increased. In addition, when the electromagnetic valve V of (3) is in the fully open state, it is possible to ensure a flow rate substantially the same as when the thermostat valve 4 and the electromagnetic valve V of (4) are in the fully open state. That is, even when the cooling water amount for the cylinder head Ea is not sufficiently obtained due to the flow path resistance of the radiator 3, if the solenoid valve V is opened, the cooling water flows to the cylinder block Eb having a relatively small flow path resistance. Therefore, the amount of cooling water flowing through the cylinder head Ea can be significantly increased.

  Returning to FIG. 2, when the high load condition of the engine E is satisfied under the condition that the temperature of the cooling water is lower than the set temperature and the thermostat valve 4 is closed (# 23 Yes determination), the opening degree of the solenoid valve V Is increased to increase the circulation amount of the cooling water to the cylinder block Eb (# 24). The opening degree of the solenoid valve V may be adjusted according to the charging efficiency and the temperature of the cooling water, or may be always fully opened. When the opening degree of the electromagnetic valve V is adjusted according to the charging efficiency or the cooling water temperature, the opening degree is set to be larger as the charging efficiency becomes higher or the cooling water temperature becomes higher.

  Next, when the temperature of the cooling water becomes equal to or higher than the set temperature, the thermostat valve 4 is opened, the cooling water flows through the radiator 3 and the cylinder head Ea is cooled (# 22 Yes determination). At this time, the electromagnetic valve V is opened to allow cooling water to flow through the second flow path 12, and the cylinder block Eb is cooled in addition to the cylinder head Ea (# 25). At this time, the opening degree of the solenoid valve V may be adjusted according to the charging efficiency and the temperature of the cooling water, as in # 24, or may be always fully opened. The timing for opening the electromagnetic valve V may be after a predetermined time has elapsed since the thermostat valve 4 opened, and is not particularly limited.

  Next, it is determined whether or not the temperature of the cooling water has become equal to or higher than a predetermined value (for example, 100 ° C.) greater than the set temperature (# 26). When the temperature of the cooling water is equal to or higher than the predetermined value (# 26 Yes determination), the cooling water is prioritized and the opening of the solenoid valve V is reduced (# 27). The opening degree of the electromagnetic valve V is adjusted according to the heat radiation amount of the radiator 3. Specifically, for example, the opening degree of the electromagnetic valve V is set to be smaller as the environmental temperature is higher and the heat radiation amount of the radiator 3 is smaller. As a result, the cooling water is reliably cooled, so that the cooling efficiency of the engine E can be increased.

  Next, it is determined whether the rotational speed of the engine E is a predetermined value (for example, 2000 rpm) or less and a high load condition is satisfied (# 28). As described above, the case where the high load condition is satisfied in the present embodiment is a case where the charging efficiency of the engine E is a predetermined value (for example, 60%) or more.

  When the rotational speed of the engine E is equal to or less than a predetermined value and a high load condition is satisfied (# 28 Yes determination), the opening of the solenoid valve V is increased to increase the flow rate of the cooling water to the cylinder block Eb (# 29). At this time, the opening degree of the solenoid valve V may be adjusted according to the charging efficiency and the temperature of the cooling water, as in # 24, or may be always fully opened. Next, the determinations of # 26 to # 29 are repeated until the engine E stops (# 30 Nо determination).

[Function and effect]
As in this embodiment, in a situation where the cooling water is low and the thermostat valve 4 is closed, if the high load condition of the engine E is satisfied, the opening degree of the electromagnetic valve V is adjusted to cool the cylinder head Ea. Water circulation can be greatly increased. As a result, the combustion temperature in the combustion chamber can be lowered to prevent knocking. Moreover, warming-up can be promoted by circulating cooling water through the cylinder block Eb in addition to the cylinder head Ea.

  In this embodiment, the pump P is constituted by a mechanical water pump that generates a driving force in accordance with the rotational speed of the engine E. Therefore, even after the thermostat valve 4 is opened, When the rotational speed is low, the amount of cooling water for the cylinder head Ea is small. When the load on the engine E increases in this state, the combustion temperature in the combustion chamber increases and knocking is likely to occur. Therefore, as in the present embodiment, when the engine speed is equal to or lower than a predetermined value and the high load condition of the engine E is satisfied, the opening degree of the solenoid valve V is adjusted and the cooling water for the cylinder block Eb is adjusted. If the circulation amount is increased, knocking can be prevented.

  The present invention is applicable to a cooling device for an internal combustion engine that cools the internal combustion engine with cooling water.

3 Radiator 4 Thermostat valve 5 Control unit 11 First flow path 12 Second flow path 28 Solenoid valve E Engine (internal combustion engine)
Ea Cylinder head Eb Cylinder block P Pump V Solenoid valve X Cooling device for internal combustion engine

Claims (4)

A pump for circulating cooling water to the internal combustion engine;
A first flow path that is a path through which the cooling water circulates between the cylinder head and the radiator by the driving force of the pump;
A thermostat valve disposed in the first flow path;
Of the first flow path, the second flow path bypasses the downstream side of the cylinder head, the upstream side of the radiator and the thermostat valve, and the downstream side of the radiator and the thermostat valve, and passes through the cylinder block. A flow path;
A solenoid valve disposed in the second flow path;
A cooling device for an internal combustion engine, comprising: a controller that controls opening and closing of the electromagnetic valve.   2. The internal combustion engine according to claim 1, wherein when the knocking condition for the internal combustion engine is satisfied, the control unit adjusts an opening degree of the electromagnetic valve so as to increase a flow amount of the cooling water flowing through the cylinder head. Cooling system.   The cooling apparatus for an internal combustion engine according to claim 2, wherein the knocking condition is satisfied when the temperature is lower than a temperature at which the thermostat valve is opened and a high load condition of the internal combustion engine is satisfied. The pump is configured to generate a driving force in proportion to the rotational speed of the internal combustion engine,
The time when the knocking condition is satisfied is when the number of revolutions of the internal combustion engine is equal to or less than a predetermined value after the thermostat valve is opened and a high load condition of the internal combustion engine is satisfied. Cooling device for internal combustion engine.

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