JP7125668B2 - vehicle cooling system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vehicle cooling device.

In a vehicle, in order to maintain the engine temperature (engine cooling water temperature) at a predetermined temperature, engine cooling water is circulated through a radiator that is cooled (dissipates heat) by running wind. Patent Literature 1 discloses that a grille shutter is provided in front of a radiator, and the degree of opening of the grille shutter is changed and controlled according to the engine cooling water temperature and the vehicle speed. As the degree of opening of the grille shutter is increased, the amount of running air introduced into the radiator is increased, and the cooling capacity of the radiator is improved.

Japanese Patent Application Laid-Open No. 2007-1503

By the way, in a vehicle engine, especially an engine using gasoline as a fuel, combustion is performed in a specific combustion mode selected from a plurality of preset combustion modes according to the operating state of the engine. Things that make it possible to do so are being put to practical use. Examples of the plurality of combustion modes include SI combustion, HCCI combustion, and SPCCI combustion. SI combustion is a common combustion mode that is usually performed, and after igniting an air-fuel mixture with a spark plug, combustion is performed by flame propagation (spark ignition combustion). HCCI combustion is compression ignition of the air-fuel mixture (compression ignition combustion). In SPCCI combustion, a part of the air-fuel mixture is ignited by the spark plug, and then the rest of the air-fuel mixture is self-ignited (partial compression ignition combustion).

As described above, there is an engine cooling water temperature that is suitable for each combustion mode. In particular, when performing HCCI combustion or SPCCI combustion, it is required to maintain the engine temperature at a considerably higher temperature than when performing SI combustion. However, merely changing and controlling the amount of cooling water circulating through the radiator in order to achieve a desirable engine temperature according to the combustion mode results in poor responsiveness, and some countermeasure is desired.

SUMMARY OF THE INVENTION The present invention has been made in view of the circumstances described above, and its object is to provide a cooling system for a vehicle that can quickly change the engine temperature to an appropriate one according to the difference in the combustion mode. .

In order to achieve the above object, the present invention adopts the following basic solutions. i.e.
an engine in which combustion is performed in a specific combustion mode selected from a plurality of preset combustion modes according to the operating state of the engine;
a radiator for circulating cooling water of the engine to cool the cooling water;
a grille shutter of an opening adjustment type for changing the amount of running wind introduced to the radiator;
control means for changing and controlling the opening degree of the grille shutter in accordance with the specific combustion mode executed in the engine;
It seems to be equipped with

According to the basic solution described above, the opening of the grille shutter is changed to change the amount of running wind introduced to the radiator, thereby changing the cooling capacity of the radiator. Therefore, by changing and controlling the opening degree of the grille shutter according to the combustion mode executed in the engine, it is possible to quickly change the engine temperature to an appropriate one according to the difference in the combustion mode.

Based on the above basic solution method, the present invention adopts the following solution method.

A target temperature of the cooling water is set for each of the plurality of combustion modes,
The control means changes and controls the opening degree of the grill shutter so as to achieve the target temperature.
It is like this. In this case, it is preferable to bring the engine temperature to the target temperature set according to the combustion mode.

Further comprising an electric fan that adjusts the flow rate of the air flowing to the radiator,
The control means controls the electric fan in addition to controlling the grille shutter so that the temperature of the cooling water becomes the target temperature.
It is like this. In this case, the electric fan can also be used to bring the engine temperature to the target temperature more quickly.

Further comprising cooling water temperature detection means for detecting the temperature of the cooling water,
The control means controls the opening degree of the grille shutter to be changed stepwise based on the actual cooling water temperature detected by the cooling water temperature detection means, while the target temperature and the actual cooling water temperature are controlled. controlling the electric fan based on the difference;
It is like this. In this case, the responsiveness of the electric fan is higher than the responsiveness of the opening of the grille shutter. Therefore, by changing the opening degree of the grille shutter in stages, the opportunity to change the opening degree of the grille shutter, which is less responsive, is reduced, while the highly responsive electric fan quickly brings the engine temperature to the target temperature. can do. Furthermore, since feedback control is performed so that the actual cooling water temperature becomes the target temperature, the engine temperature can be accurately changed to a temperature suitable for the combustion mode.

The plurality of combustion modes include at least SI combustion in which an air-fuel mixture is ignited by a spark plug and burned by flame propagation, and a part of the air-fuel mixture is ignited by the spark plug and the remaining air-fuel mixture is self-ignited. SPCCI combustion is set . In this case, SPCCI combustion can be performed, which is preferable for improving fuel consumption. In addition, it is preferable in terms of quickly changing the engine temperature to a temperature suitable for SPCCI combustion and ensuring SPCCI combustion.

A target temperature of the cooling water is set for each of the plurality of combustion modes , and the target temperature when performing SPCCI combustion is set to be higher than the target temperature when performing SI combustion,
Cooling water temperature detection means for detecting the actual temperature of the cooling water,
Equipped with an electric fan that adjusts the flow rate of the air flowing to the radiator,
The control means controls the grill shutter and the electric fan so that the temperature of the cooling water becomes the target temperature.
It is like this. In this case, the same effect as the effect corresponding to claim 5 can be obtained. In addition, by using both the grille shutter and the electric fan, it is possible to quickly and greatly change the cooling capacity of the radiator, and feedback control is performed so that the actual cooling water temperature reaches the target temperature, thereby reducing the engine temperature. This is preferable for quickly and accurately changing the temperature to a temperature suitable for the combustion mode. Of course, since the target temperature for SPCCI combustion is set higher than the target temperature for SI combustion, it is preferable to ensure that SPCCI combustion is performed.

The cooling water temperature detection means detects the temperature of the cooling water at an inlet portion to the engine . In this case, it is preferable to set the cooling water temperature to the target temperature without being affected by the cooling water heating by the engine.

According to the present invention, it is possible to quickly change the engine temperature to an appropriate one according to the difference in combustion mode.

1 is a side sectional view showing an example of an engine to which the present invention is applied; FIG. Fig. 2 is a left side view of Fig. 1; FIG. 2 is a perspective view of a state in which the cover member of the engine is partially opened, as seen from the front upper side; FIG. 3 is a side view showing the arrangement relationship among the engine, radiator, grille shutter, and electric fan. The perspective view which looked at the grille shutter from diagonally forward. FIG. 4 is a characteristic diagram showing an example of setting of combustion mode according to the operating state of the engine; The figure which shows the example of the control system of this invention in a block diagram. 4 is a flowchart showing a control example of the present invention; FIG. 5 is a diagram showing an example of setting the opening degree of the grille shutter according to the cooling water temperature of the engine;

In FIG. 1, an engine 1 is an in-line four-cylinder reciprocating engine in which four cylinders 2 are arranged in series, and the engine 1 uses gasoline as fuel.

Each cylinder 2 is provided with a fuel injection valve 3 for directly injecting fuel into the cylinder and a spark plug 4 . A transmission 30 is connected to the engine 1 (for example, a gear-type multi-stage transmission having a torque converter).

In FIG. 1, 5 is a cylinder block, 6 is a cylinder head, 7 is a cylinder head cover, and 8 is an oil pan. As shown in FIG. 2, most of the outer peripheral surface of the engine 1, including the transmission 30, is covered with a cover member 20 in order to improve heat insulation (the engine 1 is of a capsule type). ). The cover member 20 is roughly divided into an upper cover member 21 , a lower cover member 22 and a transmission cover member 23 .

The upper cover portion 21 covers the engine 1 from above the cylinder block 5 . The lower cover portion 22 covers the upper and lower parts of the cylinder block 5 . The transmission cover portion 23 covers the transmission 30 almost entirely. Each of the cover portions 21 to 23 can be made of, for example, a heat-resistant synthetic resin, and a separate heat insulating material can be adhered to the inner surface thereof.

The upper cover portion 21 is divided into a fixed member 21A located on the lower side and a movable member 21B located on the upper side. As shown in FIG. 2, the front end portion of a bracket 24 fixed to the vehicle body is rotatably connected to the rear portion of the movable member 21B, and the rotation center is indicated by symbol α.

3 and 4 show a state in which the engine 1 and the like are mounted on a vehicle V. FIG. However, in FIG. 4, the cover member 20 other than the movable member 21 is omitted. As shown in FIG. 3, with the bonnet 31 open, the movable member 21B is swung upward about the rotation center α, thereby exposing the cylinder head cover 7 and the like to ensure maintainability. .

FIG. 3 shows a state in which the intake air intake port 9 of the engine 1 is open forward. The intake port 9 is located directly above the shroud upper 32 (located in the vicinity of the radiator, i.e., directly above the radiator, which will be described later). The shroud upper 32 connects the front ends of the left and right wheel aprons. A pair of left and right radiator shrouds 33 extend downward from the left and right ends of the shroud upper 32, as shown in FIG. A lower end of the radiator shroud 33 is connected to a front end of a front subframe (not shown). A radiator, which will be described later, is arranged between a pair of left and right radiator shrouds 33 .

Next, the structure near the front portion of the engine 1 will be described with reference to FIG. First, in front of the engine 1, a radiator 40 through which cooling water for the engine 1 is circulated is arranged. A pair of upper and lower electric fans 50 are arranged immediately behind the radiator 40 . A drive motor for the electric fan 50 is indicated at 51 .

A grille shutter 60 is arranged in front of the radiator 40 . In the embodiment, as shown in FIG. 5, the grille shutter 60 has a plurality of fins (louvers) 61 that extend in the vehicle width direction and are arranged in two rows on the left and right sides. It has become. Each fin 61 is interlocked with each other by a connecting rod or the like (not shown). An electric motor 62 for driving the fins 61 is provided at a substantially intermediate portion of the grille shutter 60 in the vehicle width direction. By controlling the drive of the motor 62, the opening of the fins 61, that is, the grille shutter 60 is changed between the fully closed state and the fully opened state in a stepwise or continuously variable manner. As the degree of opening of grille shutter 60 (fins 61 ) increases, the amount of running air introduced into radiator 40 increases, and the cooling capacity of radiator 40 increases. The aforementioned intake air intake port 9 is positioned slightly higher than the upper end of the grille shutter 60 so that the introduction of running air into the intake port 9 is not hindered by the grille shutter 60 .

FIG. 6 is a characteristic diagram for changing the combustion mode according to one operating state (operating region) of the engine. In FIG. 6, five regions A1 to A5 are set using the engine speed and the engine load (eg accelerator opening) as parameters. Areas A1 to A3 are areas in which SPCCI combustion is performed. Regions A4 and A5 are regions in which SI combustion is performed.

Regions A1 to A3 where SPCCI combustion is performed are relatively low speed regions below a predetermined engine speed. Of these, in the region A1, which is the low load region, the excess air ratio λ is made sufficiently larger than 1 (eg, λ=25 to 30, an air-fuel ratio sufficiently leaner than the stoichiometric air-fuel ratio). Also, in the region A2, which is the middle load region, λ=1 (that is, the stoichiometric air-fuel ratio). Furthermore, in the high load region A3, λ is set to 1 or less (the stoichiometric air-fuel ratio or an air-fuel ratio richer than that).

A region A4 in which SI combustion is performed is a region in which the engine speed is low and the load is high, and λ=1. Further, the region A5 where SI combustion is performed is a relatively high speed region, and λ is set to 1 or less (the stoichiometric air-fuel ratio or an air-fuel ratio richer than that).

A target temperature (target cooling water temperature) of the engine 1 when performing the above-described SI combustion is set to a low temperature, for example, 90.degree. Also, the target temperature (target cooling water temperature) of the engine 1 when performing SPCCI combustion is set to a high temperature, for example, 105.degree. Each target cooling water temperature is the temperature at the inlet of the cooling water to the engine 1 .

FIG. 7 shows an example control system of the present invention. In the figure, U is a controller (control unit) configured using a microcomputer, which controls fuel injection and ignition according to the combustion mode, and controls the electric fan 50 and the grill shutter 60 described above. . The controller U (memory as storage means therein) stores a map for dividing the combustion mode into regions according to the operating state of the engine shown in FIG. 6 and the target cooling water temperature according to the combustion mode.

The controller U receives detection signals from various sensors S1 to S3. A sensor S<b>1 is a temperature sensor that detects the coolant temperature at the inlet to the engine 1 . A sensor S2 is a rotation speed sensor and detects the rotation speed of the engine 1. The sensor S3 is a load sensor (for example, an accelerator opening sensor) and detects the engine load.

The controller U controls the fuel injection valve 3, the spark plug 4, the electric fan 50 (the motor 51 thereof), and the grill shutter 60 (the motor 62 thereof).

Next, details of control by the controller U will be described with reference to the flowchart of FIG. Incidentally, in the following description, Q indicates a step. First, in Q1, the detected data from the sensors S1 to S3 are input, and the combustion mode corresponding to the current engine speed and engine load and the corresponding target temperature (target cooling water temperature) are determined. be.

After Q1, it is determined in Q2 whether the combustion type to be performed is SI combustion. If the determination in Q2 is YES, it is determined in Q3 whether or not the actual cooling water temperature detected by the temperature sensor S1 is higher than the target temperature (for example, 90° C.) for SI combustion. When the determination in Q4 is YES, in Q4, the grille shutter 60 is driven and controlled to open by one step. By increasing the opening degree of the grille shutter 60, the cooling capacity of the radiator 40 is improved, and the actual cooling water temperature is controlled to decrease.

After Q4, in Q5, it is again determined whether or not the actual coolant temperature detected by the temperature sensor S1 is higher than the target temperature for SI combustion. When the determination in Q5 is YES, in Q6, the electric fan 50 is driven (on state, maximum drive). As a result, the cooling capacity of the radiator 40 is further enhanced, and the actual cooling water temperature is controlled to further decrease. Incidentally, the drive level of the electric fan 50 may be set in a plurality of steps, and in Q6, the fan may be driven at a level higher than the current level by one step.

After the above Q6, return to Q1. By repeating the processes Q3 to Q6, the actual cooling water temperature is quickly lowered to the target temperature for SI combustion. After Q4, the process of Q5 can be performed after a predetermined delay time (for example, several seconds to ten and several seconds) has passed. Similarly, the process of Q3 can be performed after a predetermined delay time (for example, several seconds to ten and several seconds) has passed after Q6. After Q6 and Q9, it is also possible to return to Q3 (in this case, considering the possibility that the combustion mode will be changed until the cooling water temperature converges to the target temperature, the combustion It is also possible to perform determination of the mode and determination of the target temperature accordingly in separate routines so that the processing in Q2 is started when the combustion mode is changed).

When the determination in Q2 is NO, the processes of Q10 to Q16 are performed. The processing of Q10 to Q16 is a control when the target temperature is raised to, for example, 105° C. corresponding to SPCCI combustion, and corresponds to the processing of Q3 to Q9, so redundant description thereof will be omitted.

FIG. 9 shows a second embodiment of the invention. In this embodiment, the opening degree of the grille shutter 60 is changed stepwise based on the actual cooling water temperature detected by the temperature sensor S1. The degree of opening of the grille shutter 60 is changed stepwise from 0 (fully closed) to A1 to A4 (fully opened). Also, for the actual cooling water temperature, temperature thresholds are set in six stages from t1 to t6. The temperature thresholds are, for example, 80° C. for t1, 85° C. for t2, 90° C. for t3, 95° C. for t4, 100° C. for t5, and 110° C. for t6. With temperature threshold t4 as a boundary, a temperature range higher than that is used mainly for SPCCI combustion, and a temperature range lower than that is used mainly for SI combustion.

When the opening of the grille shutter 60 is increased, it changes as indicated by the solid line in the figure. Further, when the opening degree of the grille shutter 60 is decreased, it changes as indicated by the dashed line in the figure. A hysteresis is set between the increase and decrease of the opening of the grille shutter.

The degree of opening of the grille shutter 60 is basically increased as the actual cooling water temperature increases. By adjusting the opening degree of the grille shutter 60, the actual cooling water temperature is converged to the target temperature or a temperature in the vicinity thereof according to the combustion mode.

In addition to adjusting the opening degree of the grille shutter 60 as shown in FIG. 9, it is preferable to use the electric fan 50 to control the target temperature. More specifically, the electric fan 50 can be controlled based on the difference between the actual cooling water temperature and the target temperature (to reduce the difference). The operation level of the electric fan 50 can be changed in two stages, ON and OFF, but it can also be changed in three or more stages, or continuously variable. Although different from FIG. 9, the opening degree of the grille shutter 60 can be controlled so as to be continuously variable according to the actual cooling water temperature.

Although the embodiments have been described above, the present invention is not limited to the embodiments, and can be appropriately modified within the scope of the claims, including the following cases, for example. .
(1) As the plurality of combustion modes, for example, any two or more of the three combustion modes of SI combustion, SPCCI combustion, and HCCI combustion can be set. Specifically, switching between two combustion modes of SI combustion and HCCI combustion, switching between two combustion modes of SPCCI combustion and HCCI combustion, and switching between two combustion modes of SI combustion, SPCCI combustion, and HCCI combustion. switching between two combustion modes. When performing HCCI combustion, for example, the area A1 in FIG. 6 can be set as the HCCI combustion area. Further, the target temperature (target cooling water temperature) of the engine 1 when performing HCCI combustion is preferably set higher than the target temperature when performing SPCCI combustion.
(2) The number of cylinders of the engine 1 does not matter, and may be, for example, 3 cylinders, 6 cylinders, or the like. Further, the engine 1 is not limited to a series type, and an appropriate type such as a V type or a horizontally opposed type can be selected.
(3) The cover member 20 that covers the engine 1 may not be provided.
(4) Adjustment of the amount of cooling water introduced into the radiator 40 can be performed by an appropriate method. For example, a thermostat can be used to set the amount of cooling water to increase as the temperature of the cooling water increases. Also, by using an opening-adjustable solenoid valve, it is possible to control the amount of cooling water so that the higher the actual cooling water temperature is relative to the target cooling water temperature, the greater the amount of cooling water.
(5) The purpose of the present invention is not limited to what is expressly stated, but implicitly includes what is substantially preferred or expressed as an advantage.

INDUSTRIAL APPLICABILITY The present invention is suitable for application to a vehicle equipped with an engine that is driven by changing the combustion mode.

V: Vehicle 1: Engine 2: Cylinder 3: Fuel injection valve 4: Spark plug 9: Intake (for intake air)
32: Shroud upper 33: Radiator shroud 40: Radiator 50: Electric fan 51: Electric motor 60: Grill shutter 61: Fins 62: Electric motor

Claims (5)

an engine in which combustion is performed in a specific combustion mode selected from a plurality of preset combustion modes according to the operating state of the engine;
a radiator for circulating cooling water of the engine to cool the cooling water;
a grille shutter of an opening adjustment type for changing the amount of running wind introduced to the radiator;
control means for changing and controlling the opening degree of the grille shutter in accordance with the specific combustion mode executed in the engine;
with
A target temperature of the cooling water is set for each of the plurality of combustion modes,
The control means changes and controls the opening degree of the grill shutter so as to achieve the target temperature,
Further comprising an electric fan that adjusts the flow rate of the air flowing to the radiator,
The control means controls the electric fan in addition to controlling the grille shutter so that the temperature of the cooling water becomes the target temperature;

Further comprising cooling water temperature detection means for detecting the temperature of the cooling water,
The control means controls the opening degree of the grille shutter to be changed stepwise based on the actual cooling water temperature detected by the cooling water temperature detection means, while the target temperature and the actual cooling water temperature are controlled. controlling the electric fan based on the difference;
A vehicle cooling device characterized by: In claim 1 ,
A cooling device for a vehicle, wherein the cooling water temperature detecting means detects the temperature of the cooling water at an entrance portion to the engine. an engine in which combustion is performed in a specific combustion mode selected from a plurality of preset combustion modes according to the operating state of the engine;
a radiator for circulating cooling water of the engine to cool the cooling water;
a grille shutter of an opening adjustment type for changing the amount of running wind introduced to the radiator;
control means for changing and controlling the opening degree of the grille shutter in accordance with the specific combustion mode executed in the engine;
with
The plurality of combustion modes include at least SI combustion in which an air-fuel mixture is ignited by a spark plug and burned by flame propagation, and a part of the air-fuel mixture is ignited by the spark plug and the remaining air-fuel mixture is self-ignited. A cooling system for a vehicle, characterized in that SPCCI combustion is set. In claim 3,
A target temperature of the cooling water is set for each of the plurality of combustion modes , and the target temperature when performing SPCCI combustion is set to be higher than the target temperature when performing SI combustion,
Cooling water temperature detection means for detecting the actual temperature of the cooling water,
Equipped with an electric fan that adjusts the flow rate of the air flowing to the radiator,
The control means controls the grill shutter and the electric fan so that the temperature of the cooling water becomes the target temperature.
A vehicle cooling device characterized by: In claim 3 ,
A cooling device for a vehicle, wherein the cooling water temperature detecting means detects the temperature of the cooling water at an entrance portion to the engine.

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