JPS5928016A - Control method of cooling of water-cooled internal combustion engine for vehicle and device therefor - Google Patents

Abstract

PURPOSE:To perform cooling of cooling water appropriately always, by a method wherein a bypass circuit which is made to diverge from a circulating circuit at the lower stream of a water jacket is opened and closed according to a cooling water temperature and a flow of the cooling water of the circulating circuit is controlled according to the cooling water temperature. CONSTITUTION:A circulating circuit P1 of cooling water is constituted by arranging a water pump WP, a water jacket J and a radiator R and connecting them with each other, and a first and a second bypass circuits P2 and P3 detouring around the radiator and a cylinder block part J1 are provided by diverging the circuits P2 and P3 from the circulating circuit P1. Then, a directional control valve V2 is switched over to a conduction side of the bypass circuit P2 when a cooling water temperature T1 is less than a first established temperature T1 is less than a first established temperature t1 (for example 84 deg.C) and the directional control valve V2 is changed over to a conduction side of the circulating circuit P1 when an inequality T1>t1 is given. Then, when an inequality of T1<t2(>t1) is given, an opening of a flow adjusting valve V1 in the circuit P1 is squeezed, and when an inequality of T1>t3(>t2) is given, a titled device is controlled so as to increase the opening of the valve V1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling control method and apparatus for a water-cooled internal combustion engine for a vehicle.

Generally, a cooling system for a water-cooled internal combustion engine for a vehicle circulates cooling water discharged from a water pump through a water jacket provided in the cylinder block and cylinder head of the internal combustion engine, cools it in a radiator, and then flows it back to the water pump. It basically includes a water circulation circuit and a cooling water bypass circuit that branches off from the circulation circuit downstream of the water jacket and returns the cooling water that has passed through the water jacket to the water pump. Therefore, in order to optimally cool the internal combustion engine using the cooling device, it is necessary to control the cooling capacity of the cooling device in accordance with variously changing operating conditions.

By the way, conventionally, the cooling water flowing into the circulation circuit or the bypass circuit is controlled by a thermovalve that is provided at a branch part of the circulation circuit and the bypass circuit and operates in response to the temperature of the cooling water. In such control, the temperature of the cooling water flowing in the water jacket cannot be accurately controlled due to the hysteresis of the thermovalve (i.e., the difference between the maximum and minimum temperature of the cooling water controlled by the thermovalve). (because it is not possible to reduce the temperature), the operating timing of the thermovalve is set so that the maximum temperature of the cooling water controlled by the thermovalve approximates the optimum cooling temperature of the internal combustion engine. (This is to prevent the internal combustion engine from heating up abnormally and becoming inoperable.) Therefore, if the temperature of the cooling water is close to its minimum temperature, the internal combustion engine will not be able to operate as needed. ”2, the so-called cooling 1
N loss increases, leading to a decrease in fuel efficiency.

The present invention has been made in view of the above circumstances, and its purpose is to quickly and accurately control the temperature of the cooling water flowing inside the water jacket using simple means to reach the optimum cooling temperature, thereby improving fuel efficiency. It is in.

The gist of the present invention is, in a cooling device for a water-cooled internal combustion engine for a vehicle, to cut off the circulation circuit and open the bypass circuit when the temperature of the cooling water in the water jacket is lower than a first set temperature. Further, when the temperature of the cooling water is equal to or higher than the first set temperature, the bypass circuit is shut off and the circulation circuit is opened, so that the flow rate of the cooling water flowing through the circulation circuit is controlled according to the speed change state of the vehicle and the above-mentioned. The temperature of the cooling water in the water jacket is set to a predetermined value depending on the state of change in the intake negative pressure of the internal combustion engine, and the temperature of the cooling water in the water jacket is set to the first value.
When the fA is lower than the second set temperature higher than the set temperature
! The flow rate of cooling water flowing through the i-ring circuit is reduced, and
- Cooling of a water-cooled internal combustion engine for a vehicle in which the flow rate of the cooling water flowing through the circulation circuit is increased when the temperature of the cooling water in the tank is equal to or higher than a third set temperature which is higher than the second set temperature. Control method and device. In this method and device, the flow rate of the cooling water flowing through the circulation circuit can be set to a predetermined value depending on the expected operating conditions, especially the vehicle speed and intake negative pressure, so that the inside of the water jacket can be adjusted to a predetermined value. The temperature of the flowing cooling water can be quickly brought to the optimum cooling temperature, and the flow rate of the cooling water flowing through the circulation circuit can be controlled in accordance with the temperature change of the cooling water flowing inside the water shaker throat. , the temperature of the cooling water flowing inside the water jacket can be precisely controlled to the optimum cooling temperature. Therefore, cooling loss can be reduced and fuel efficiency can be improved.

An embodiment of the present invention will be described below based on the drawings. In FIG. 1, an inlet Ja of a water jacket J provided in a cylinder block E1 and a cylinder head E2 of an internal combustion engine E is connected to an outlet WPb of a water pump WP, and an outlet Jb of the water jacket J is connected to a radiator R.
The inlet port Ra of the radiator R is connected to the inlet port Rb of the radiator R, and the inlet port Pa of the water pump WP is connected to form a cooling water circulation circuit P1. Furthermore, a bypass circuit P2 is formed downstream of the water jacket J, branching from the circulation circuit PL and bypassing the radiator R. Furthermore, a circulation circuit P is provided downstream of the water pump WP.
A second bypass circuit P3 is formed which branches off from the cylinder block portion J1 of the water jacket IJ.

A variable throttle valve Vl for controlling the flow rate of cooling water flowing through the circulation circuit PI is interposed in the circulation circuit PI, and a circulation circuit P
A switching valve 2 is interposed to selectively close either one of the second bypass circuit 1 and the bypass circuit P2 and communicate the other, and the second bypass circuit 1) controls the flow rate of cooling water flowing through the bypass circuit P3. A second variable throttle valve (3) is installed.

The variable throttle valve ■1 is configured such that its opening degree is controlled according to the negative pressure obtained by the negative pressure regulating valve ■4,
The negative pressure regulating valve 4 operates in response to a signal from the electric control circuit 10, and adjusts the negative pressure obtained from the intake manifold 20 and stored in the tank 22 via the check valve 21, thereby forming a variable throttle valve. ■It is configured to be given to 1. The switching valve V2 is connected to the tank 2 provided via the electromagnetic switching valve ■5.
The electromagnetic switching valve ■5 operates in response to a signal from the electrical control circuit 10, connects the negative pressure to the switching valve ■2, and also switches the switching valve when not in operation. ■It is configured so that the atmosphere is connected to 2. The second variable throttle valve ■3 is configured such that its opening degree is controlled according to the negative pressure obtained by the negative pressure regulating valve ■6,
The negative pressure regulating valve V6 operates in response to a signal from the electric control circuit 10, and is configured to regulate the negative pressure stored in the tank 22 and apply it to the variable throttle valve (3).

Further, the radiator R is provided with a cooling fan F and a shutter ST. The cooling fan F is driven by an electric motor FM, and the electric motor FM is configured so that its rotational speed is controlled by an electrical control circuit 10 and a speed change circuit 30. The shutter ST is configured to be opened and closed by an actuator A, and the actuator A is configured to be operated by negative pressure inside the tank 22 applied via an electromagnetic switching valve (7). Solenoid switching valve■
7 is configured to operate in response to a signal from the electrical control circuit 10 to connect negative pressure to the actuator A, and to connect the actuator A to the atmosphere when not in operation,
When the electromagnetic switching valve v7 is activated, the actuator A is activated to open the shutter ST, and when it is not activated, the actuator A is inactive and the shutter S'F is closed.

The electrical control circuit 10 receives, as its input signals, a signal %D1 representing the temperature of the cooling water detected by a water temperature sensor S1 provided near the outlet of the water jacket J, and a second No. 1 innomous circuit P3 in the cylinder head E2. Signal 1) representing the temperature of the cooling water detected by the water temperature sensor S2 installed in
2. Signal 1) representing the vehicle speed detected by the vehicle speed sensor S3 provided on the drive shaft 40. 3. Signal 1) representing the intake negative pressure detected by the negative pressure sensor S4 provided on the intake manifold 20 of the internal combustion engine E. 4. , and temperature sensor S5
The above-mentioned negative pressure 1) 1 is applied in accordance with these input signals Di-D5.
1 Valve adjustment V4. V6, solenoid switching valve V5. It is composed of a microcomputer that stores and executes a program shown in the flowchart of FIG. 2 in advance to generate various output signals for controlling the operation of V7 and electric motor F'M.

In the first step 51 of the flowchart shown in FIG. 2, the microcomputer is activated by turning on the ignition key and starts executing the program. Thus, in the second step 52, the microcomputer is initialized, and in the third step 53, the temperature T1 of the cooling water near the outlet of the water jacket J is equal to or higher than the first set temperature tl (for example, 84°C). Determine if it is. Here, if the temperature TI of the cooling water is less than the first set temperature t1, in step 53a, the negative pressure regulating valve V4. A first output signal is generated and applied to V6 and the electromagnetic switching valve V5, and in response to this first output signal, both throttle valves 1 and V3 are minimized in their opening degrees, and the switching valve V2 is activated. After that, the process proceeds to the third step 53. When the cooling water temperature T1 is equal to or higher than the first set temperature t1, the fourth
Proceed to step 54. In the fourth step 54, it is determined based on the input signals D1 to D4 which driving mode the vehicle is currently in as shown in Table 1 below, and in the fifth step 55, the settings are set in advance according to the driving mode and the temperature. Determine the value. Based on these set values, the negative pressure regulating valve V4. V6, solenoid switching valve V5. V7, which generates a second output signal that controls electric motor FM.

Margin below: Table 1 Table 2 In Table 2 above, ■1 is the opening degree (%) of the variable throttle valve Vl.
), ■3 indicates the opening degree (%) of the second variable throttle valve ■3, F indicates the rotation speed (rpm) of the cooling fan F, and S
T indicates the open/closed state of the shutter ST. In addition, up I indicates a driving mode in which the vehicle speed is 35 km/h or more, up ■ indicates a driving mode in which the vehicle speed is less than 35+n/h, down l indicates a driving mode in which the vehicle speed is 35 km/h or more, and down ■ indicates a driving mode in which the vehicle speed is less than 35 + n/h. 3
High-speed hot soak I indicates a running mode in which the elapsed time is less than 20 seconds, High-speed hot soak ■ indicates a driving mode in which the elapsed time is 20 seconds or more, and Pitching hot soak ■ indicates a driving mode in which the elapsed time is less than 20 seconds. Indicates a driving mode in which the elapsed time is less than 20 seconds, "Top Real Soak" indicates a driving mode in which the elapsed time is 20 seconds or more, "Other I" indicates a driving mode in which the vehicle speed is 35 km/h or more, and "Other ■" indicates a driving mode in which the vehicle speed is less than 35 km/h. Indicates mode.

The margin below also shows the sixth step 56 of the flowchart shown in FIG.
In this step, it is determined whether the temperature T1 of the cooling water is equal to or higher than the second set temperature t2 (for example, 95° C.) which is higher than the first set temperature t1. Here, the cooling water temperature Tl is the second set temperature t
If the negative pressure #N! is less than 2, in step 56a, the opening degree of the variable throttle valve VlO is decreased by a predetermined amount. ! valve V4
The electric motor F M generates and applies a third output signal to the electric motor F M in order to reduce the rotation speed of the cooling fan F by a predetermined amount.
A third output signal is generated and applied to the output signal, and the process then proceeds to a fifth step 55. If the coolant temperature TI is equal to or higher than the second set temperature t2, the process proceeds to the seventh step 57. In the seventh step 57, the temperature Tl of the cooling water is changed to the second set temperature t2.
It is determined whether the temperature is lower than a higher third set temperature t3 (for example, 97°C).

Here, if the cooling water temperature T1 is equal to or higher than the third set temperature t3, a fourth output signal is sent to the negative pressure regulating valve v4 in order to increase the opening degree of the variable throttle valve 1 by a predetermined amount in step 57a. At the same time, a fourth output signal is generated and applied to the electric motor FM in order to increase the rotational speed of the cooling fan F by a predetermined amount, and then the process proceeds to the fifth step 55. When the cooling water temperature T1 is less than the third set temperature t3,
Proceed to the eighth step 58.

In the eighth step 58, it is determined whether the temperature T2 of the cooling water in the second bypass circuit P2 in the upper cylinder head 2 is lower than the third set temperature t3. Here, if the cooling water temperature T2 is equal to or higher than the third set temperature t3, in step 58a, the negative pressure regulating valve v6 is set to the fifth An output signal is generated and applied, after which the process proceeds to a sixth step 56. Cooling water temperature T
2 is less than the third set temperature t3, the process proceeds to the ninth step 59. In the ninth step 59, it is determined whether the temperature T2 of the cooling water is equal to or higher than the second set temperature t2. Here, if the cooling water temperature T2 is lower than the second set temperature t2h, in step 59a, the sixth variable throttle valve v6 is set to decrease the opening degree of the second variable throttle valve 3 by a predetermined amount. Generate and apply an output signal, then proceed to a sixth step 56.

If the cooling water temperature T2 is equal to or higher than the second set temperature t2, the process proceeds to the fourth step 54. 8th step 58 and 9th step
After determining "1NO" in step 59, step 58
Proceeding to the sixth step 56 via steps a and 59a is the second step.
Circulation circuit 1) by changing the opening degree of variable throttle valve ■3
This is to quickly correct the temperature TI of the cooling water, which changes as the flow rate changes. The reason why the process proceeds to the fourth step 54 after determining rYEsJ in the ninth step 59 is to optimally control the cooling water temperatures TI and T2 in accordance with changes in the driving mode.

As can be understood from the above description, in this embodiment, for example, when the internal combustion engine of a vehicle that has been stopped for a long time is started, during warm-up operation, that is, the cooling water temperature 1゛1 becomes the first set temperature. When it is less than t1, the switching valve ■2 operates to close the circulation circuit P1 and open the bypass circuit P2, and the second variable throttle valve v3 operates to close the second bypass circuit P3. Therefore, the cooling water discharged from the water pump WP passes through the cylinder block El and the cylinder head E2, and returns to the water pump WP through the bypass passage P2, but does not flow into the radiator R.

Therefore, warm-up operation is performed for a short time. Note that at this time, the second variable throttle valve 3 closes the second bypass circuit P3, and no cooling water flows into the second bypass circuit P3.

In this way, when the cooling water temperature TI becomes equal to or higher than the first set temperature t1 and the warm-up operation ends and the vehicle starts traveling, the driving mode corresponding to the driving is repeatedly determined and the switching valve ■
2 operates to open the circulation circuit P1 and close the bypass circuit P2, and the opening degrees of both throttle valves Vl and 'V3, the rotation speed of the cooling fan F, and the opening/closing state of the shutter ST are predetermined according to the above-mentioned driving mode. The settings are initialized to the values shown in Table 2. In this state, the cooling water flows through the circulation circuit P.
1 and may pass through a second bypass circuit P2 in a circular manner. ), opening degree of variable throttle valve ■1.

Depending on the rotation speed of the cooling fan F and the opening/closing of the shutter ST (
When the cooling water passes through the second bypass circuit P2, the cooling capacity (depending on the opening degree of the second variable throttle valve 3) is immediately set to a predetermined setting value, and this set cooling capacity is used to control the cylinder block E1 and The cylinder bottom I"E2 is cooled quickly and precisely.

If the cooling water temperature TI (or 1゛2) does not exceed the second set temperature t2 under this cooling condition, the opening degree of the variable throttle valve Vl (or V3) is sequentially reduced by a predetermined amount, and the cooling fan The rotation speed of F is reduced by a predetermined amount, the cooling capacity is sequentially reduced by a predetermined amount, and the cooling water temperature TI (or 1゛2
) becomes equal to or higher than the third set temperature t3, the opening degree of the variable throttle valve ■1 (or V3) is sequentially increased by a predetermined amount, and the rotation speed of the cooling fan F is increased by a predetermined amount to increase the cooling capacity. The temperature of the cooling water is increased by a predetermined amount one after another, and the temperature of the cooling water [1] and T2 are precisely controlled to be between the second set temperature t2 and the third set temperature L2.

In the above embodiment, the variable throttle valve v1 is provided in the circulation circuit P1 between the water jacket J and the radiator 8, but this variable throttle valve v1 is connected to the water pump as shown in FIG. It is also possible to implement it by providing it in the circulation circuit P1 between the WP and the water jacket 5. In this case, by setting the opening degree of the variable throttle valve ■1 to Ca (1-Cb) and the opening degree of the second variable throttle valve ■3 to Ca-Cb (however, by setting the opening degree of the variable throttle valve ■1 to Ca (1-Cb) (however, the variable throttle valve of the above embodiment Opening degree of valve V1, Cbi opening degree of second variable throttle valve ■3 in the above embodiment)
The same control as in the above embodiment can be performed. Also, the third
As shown in FIGS. (b) and (C), it is also possible to use an on-off valve V3' instead of the second variable throttle valve (3). When implementing FIG. 3(b), control similar to the above embodiment is achieved by closing the second variable throttle valve 3 of the above embodiment when the opening degree is 0% and opening at other times. can do. Further, when implementing FIG. 3(c), the opening degree of the variable throttle valve V1 is set to Ca (1-Cb), and the opening degree of the second variable throttle valve V3 in the above embodiment is 0.
%, and by opening the on-off valve V3' at other times, it is also possible to perform control similar to the above embodiment.

Further, in the above embodiment, the rotation speed of the cooling fan F and the opening/closing operation of the shutter ST are also controlled to change the amount of air passing through the radiator R, but the amount of air passing through the radiator R is changed by conventional means. The present invention can be practiced by changing the.

Furthermore, in the above embodiment, a second bypass circuit P3 and a second variable throttle valve (3) are provided to control the cylinder head E2.
Although the cylinder head can be cooled by two systems, it is also possible to carry out the present invention without providing the second bypass circuit P3 and the second variable throttle valve V3. If the cylinder head E2 can be cooled by two systems, the cylinder head E2 can be cooled quickly, so knocking, etc. can be prevented.)

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing one embodiment of the present invention, FIG. 2 is a flowchart, and FIG. 3 is a partial schematic block diagram showing another embodiment of the present invention. Explanation of symbols 10...Electrical control circuit, wp...Water pump, E...Internal combustion engine, El...Cylinder block, E
2...Cylinder head, J...Water jacket, R...Radiator, Pl...Circulation circuit, P2...
・Bypass circuit, SL...Water temperature sensor, S3...
Vehicle speed sensor, S4... negative pressure sensor, tl... first set temperature, t2... second set temperature, t3... third set temperature, ■1... variable throttle valve, ■2. ...Switching valve. Applicant Aisin Seiki Co., Ltd. Representative Patent Attorney Teru Hase −

Claims (2)

[Claims] (1) A cooling water circulation circuit in which cooling water discharged from a water pump is circulated through a water jacket provided in a cylinder block and cylinder head of an internal combustion engine, cooled by a radiator, and then returned to the water pump; In a cooling device for a water-cooled internal combustion engine for a vehicle, comprising a cooling water bypass circuit that branches off from the circulation circuit downstream and returns the cooling water that has passed through the water jacket to the water pump, When the temperature of the cooling water is less than the first set temperature, the circulation circuit is cut off and the bypass circuit is opened; and when the temperature of the cooling water is higher than the first set temperature, the bypass circuit is cut off. The circulation circuit is connected to the flow rate of the cooling water flowing through the circulation circuit, and the flow rate of the cooling water flowing through the circulation circuit is set to a predetermined value depending on the speed change state of the vehicle and the change state of the intake negative pressure of the internal combustion engine. A second cooling water whose temperature is higher than the first set temperature.
reducing the flow rate of cooling water flowing through the circulation circuit when the temperature is below a set temperature; and reducing the flow rate of cooling water flowing through the circulation circuit when the temperature of the cooling water in the water jacket is equal to or higher than a third set temperature higher than the second set temperature. A cooling control method for a water-cooled internal combustion engine for a vehicle that increases the flow rate of water. (2) a cooling water circulation circuit in which the cooling water discharged from the water pump is circulated through a water jacket provided in the cylinder block and cylinder head of the internal combustion engine, and then cooled by a radiator and returned to the water pump;
A cooling device for a water-cooled internal combustion engine for a vehicle, comprising a cooling water bypass circuit that branches from the circulation circuit downstream of the water jacket and returns the cooling water that has passed through the water jacket to the water pump. temperature detection means for detecting the temperature of the cooling water in the water jacket; negative pressure detection means for detecting the intake negative pressure of the internal combustion engine; vehicle speed detection means for detecting the speed of the vehicle; and the detected temperature detected by the temperature detection means. is lower than the first set temperature, a first output signal is generated, and the detected temperature is lower than the first set temperature.
When the detected temperature is higher than or equal to the set temperature, a second output signal representing a predetermined set value is generated according to the change state of the negative pressure and the change state of the vehicle speed detected by the negative pressure detection means and the vehicle speed detection means. an electrical control circuit that generates a third output signal when the detected temperature is less than a second set temperature higher than the second set temperature, and generates a fourth output signal when the detected temperature is equal to or higher than a third set temperature higher than the second set temperature; a switching valve that operates in response to the first output signal, and when activated cuts off the circulation circuit and connects the bypass circuit; and when not actuated, cuts off the bypass circuit and connects the circulation circuit; disposed in the circuit, the initial opening is set to the opening defined by the second output signal, the opening is decreased in response to the third output signal, and the opening is decreased in response to the fourth output signal. A cooling control device for a water-cooled internal combustion engine for a vehicle, comprising a variable throttle valve whose opening degree is increased.