JP3044503B2 - Engine cooling system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling system for an engine in which an electric water pump having a variable capacity is provided on the engine inlet side of a cooling water circulation circuit connecting an engine body and a radiator.

[0002]

2. Description of the Related Art Conventionally, such a cooling device is already well known, for example, from Japanese Patent Application Laid-Open No. 58-2418.

[0003]

In such a cooling device, in order to accurately control the operation of the water pump so that the cooling water temperature matches the operating state of the engine, the operation of the water pump must be controlled in accordance with the engine water temperature. It is desired to perform feedback control. By the way, when the engine is warmed up, it is possible to rapidly warm up the engine by feedback-controlling the water pump so that the amount of cooling water flowing through the engine body is extremely small. , The value detected by the water temperature detector becomes inaccurate. Therefore, in the case of the feedback control, it may be difficult to raise the engine water temperature to a desired value, or the engine water temperature may rise more than necessary.

Further, as shown in FIG. 15, the present inventor has found that it is effective to reduce the difference between the engine inlet water temperature and the engine outlet water temperature in order to avoid the occurrence of knocking. With such a feedback control, it is difficult to optimally control the difference between the engine inlet water temperature and the engine outlet water temperature to avoid knocking.

The present invention has been made in view of the above circumstances, and has as its object to provide an engine cooling device capable of appropriately controlling a cooling water temperature according to an operating state of the engine.

[0006]

In order to achieve the above object, an apparatus according to a first aspect of the present invention includes a water temperature detector for detecting an engine water temperature, and a feedback control and an open loop control according to the engine water temperature. Control means for controlling the operation of the water pump by switching according to the operating state of the engine.

According to a second feature of the present invention, in addition to the configuration of the first feature, the control means includes a feedback control when the engine coolant temperature is equal to or higher than a predetermined reference coolant temperature, and The open-loop control when the temperature is lower than the reference water temperature can be switched.

According to a third aspect of the present invention, in addition to the configuration of the second aspect, the control means includes a control unit for performing an open loop control when the engine water temperature is lower than the reference water temperature. A control value corresponding to the permissible minimum capacity of the water pump that guarantees substantially uniform flow of the cooling water is preset.

According to a fourth aspect of the present invention, in addition to the configuration of the first aspect, the control means includes an open loop of the water pump having a control value which continuously changes according to the engine water temperature when the engine is stopped. It is configured to perform control.

[0010]

[0011]

An embodiment of the present invention will be described below with reference to the drawings.

First, in FIG. 1, a cooling water circulating circuit 1 is formed by connecting an engine body E and a radiator R. The cooling water circulating circuit 1 is a pipeline 1a connecting an outlet of the engine body E and an inlet of the radiator R. 1 connecting the outlet of the radiator R and the inlet of the engine body E
b. A radiator R is provided between the pipelines 1a and 1b.
Are connected by a bypass circuit 2 that bypasses.

A flow control valve 3 whose opening can be changed steplessly is provided in the cooling water circulation circuit 1 in the middle of the pipe line 1b, and the bypass circuit 2 is located downstream of the flow control valve 3, ie, The engine body E is connected to the pipeline 1b. In the portion of the pipe 1b near the engine body E,
An electric water pump 4 having a variable capacity is provided.

The pipe line 1a in the cooling water circulation circuit 1 includes:
One end of each of the pipelines 6 and 7 is connected via the switching valve 5,
The other ends of both pipes 6 and 7 are connected to pipe 1 in cooling water circulation circuit 1.
b is connected between the flow control valve 3 and the water pump 4. Thus, a heater unit 8 is interposed in the middle of one pipe 6, and a control valve 9 and a transmission oil warmer 10 are sequentially installed in the middle of the other pipe 7 from the upstream side.

A radiator fan 11 attached to the radiator R is controlled on / off by a fan switch 12 disposed on the outlet side of the radiator R.
When the outlet water temperature of the radiator R becomes equal to or higher than a predetermined value, the radiator fan 11 is operated.

The flow control valve 3, the water pump 4, the switching valve 5, the control valve 9, and the fan 13 attached to the heater unit 8 are controlled by a control means 14 comprising a computer. Is the engine outlet water temperature T in the cooling water circulation circuit 1 as the engine water temperature.
Outlet water temperature detector 15 as a water temperature detector for detecting _WO ,
An inlet water temperature detector 16 for detecting an engine inlet water temperature _TWI in the cooling water circulation circuit 1 and a radiator water temperature detector 1 for detecting a radiator water temperature _TWR at an outlet of the radiator R.
7, the oil temperature detector 18 for detecting the temperature T _O of the transmission oil, the outside air temperature detector 1 for detecting the outside air temperature T _D
9, vehicle interior temperature detector 20 for detecting the vehicle interior temperature T _R, the rotation speed detector 21 for detecting an engine speed N _E, the intake pressure detector 22 for detecting the engine intake pressure P _B, detecting the atmospheric pressure P _A Atmospheric pressure detector 23 and knocking detector 24 for detecting knocking by vibration of engine body E
Etc. are respectively connected.

The control means 14 calculates the temperatures T _WO , T _WI , T _WR , T _O , T _D , T _R , the engine speed _NE , the engine intake pressure P _B , the atmospheric pressure P _A , In addition, the operation of the flow control valve 3, the water pump 4, the switching valve 5, the control valve 9, and the fan 13 is controlled in accordance with the output of the knocking detector 24 and the like. A control procedure set by the control means 14 regarding the operation control of the control will be described.

FIG. 2 shows a main routine of a control procedure set by the control means 14 to control the operation of the water pump 4. When the engine is operating, control by a subroutine of a normal mode and a subroutine of a knock determination mode are executed. When the engine stops, control is performed by a subroutine of a post-stop mode.

[0019] FIG. 3 shows a subroutine of the normal mode, the first step S1, the engine speed N _E, the engine intake pressure P _B and the engine outlet water temperature T _WO is read in as a parameter, in a second step S2 It is determined whether the engine outlet water temperature T _WO is equal to or higher than a preset reference water temperature T _WS, for example, 80 ° C. When it is determined in this second step S2 that T _WO <T _WS , the process proceeds to a third step S3.

The electric motor of the water pump 4 is a DC motor, and the capacity of the water pump 4 changes by controlling the duty ratio. Thus, the third
In step S3, the duty ratios D _O1 , D _O2 , D _O3 , and D _O3 are set according to a map set in advance as shown in FIG. 4 according to the engine outlet water temperature T _WO and the engine intake pressure P _B.
Duty ratios such as D _O4 and D _O5 are set. For example, D _O1 is 5%, D _O2 is 10%, D _O3 is 20%, and D _O4 is 3%.
0% and D _O5 are 40%. Thus, the engine outlet water temperature T
_{When WO} and the engine intake pressure P _B are low, the duty ratio D _O is set to about 5%, and this value is used to guarantee substantially even flow of cooling water in the engine It is set as an allowable minimum value that does not cause boiling.

Thereafter, in a fourth step S4, the search data
Duty ratio D_OThe motor of the water pump 4 operates based on
I'm impressed. That is, the engine outlet water temperature T_WOIs reference water
Warm T _WSIf it is less than, the engine outlet water temperature T_WOAnd
And engine intake pressure P_BFixed duty determined according to
Ratio D_OThe motor of the water pump 4 is controlled by open loop
Will be.

When it is determined in the second step S2 that T _WO ≧ T _WS , the feedback control is executed in accordance with the fifth step S5 to the tenth step S10, and in the fifth step S5, the engine rotation is performed. the predetermined map as shown in Figure 5 in accordance with the number N _E and the engine intake pressure P _B, the target outlet water temperature T _WOTR is searched. Thus, in FIG. 5, target outlet water temperature T _WOTR1 is set, for example, to 80 to 90 ° C., and target outlet water temperature T _WOTR2 is set, for example, to 130 ° C.

In the next sixth step S6, the engine speed
Number N_EAnd engine intake pressure P_BAs shown in FIG.
The reference duty ratio D set in advance_FSIs searched
It is. In FIG. 6, the engine speed N_EAnd engine
Intake pressure P_BAccording to the reference duty ratio D_FS5 territories
Area D_FS1, D_FS2, D_FS3, D_FS4, D_FS5Is set
And for example D_FS1Is 5%, D_FS2Is 10%, D
_FS3Is 20-50%, D _FS4Is 50-60%, D_FS5Is
80 to 100%.

In a seventh step S7, a water temperature difference ΔT _WO (= T _WO) between the engine outlet water temperature T _WO and the target outlet water temperature T _WOTR.
-T _WOTR) is calculated, in the eighth step S8, the feedback control value D _F is calculated as _{(D FS + K · ΔT WO} ). Thus, K is a gain.

In a ninth step S9, an eighth step S8
Feedback control value D obtained by _FIs the minimum allowable value D
_FMINIs determined to be less than_F<D_FMINIn
D in the tenth step S10_F= D_FMINTosa
After that, the process proceeds to the fourth step S4, where D_F≧ D_FMINSo
The fourth step, bypassing the tenth step S10.
Proceed to step S4.

FIG. 7 shows a subroutine of the knock determination mode. In the first step L1, it is determined whether or not the flag F is "1". The flag F indicates whether or not a knocking state is present. F = 1 indicates a knocking state, and F = 0 indicates a non-knocking state. When F = 0 in the first step L1, the process proceeds to the second step L2.
Go to step L7.

In the second step L2, the knocking detector 2
4 to determine whether knocking has occurred,
When knocking has not occurred, the process proceeds to the third step L3, and the target outlet water temperature _TWOTR is searched according to the map of FIG.

Knocking occurred in the second step L2
Is determined in the fourth step L4.
F is set to "1". Then in the fifth step L5
Is the bias value D of the target outlet water temperature._TWIs (D_TW= D_TWO−
X_D1) Is calculated according to the following equation: Where D_TWO
Is, for example, 0 degrees C, and X_D1Is 5 degrees C
You. In the sixth step L6, the target outlet water temperature T_OWTRFigure 5
The bias value D_TW(T_WOTR
= Map value + D_TW). Where D
_TWIs a negative value (for example, -5 degrees C) in the fifth step L5.
In the sixth step L6, FIG.
Of the target outlet water temperature T_OWTRAs
Will be set.

In a seventh step L7, a knocking detector
Determines whether knocking has occurred by the output of 24
When knocking has occurred, the eighth step L
8 and the target outlet water temperature bias value D_TWIs (D_TW= D
_TW-X_D2) Is calculated according to the following equation: Where X
_D2Is 3 degrees C, for example. In the next ninth step L9
Is the target outlet water temperature T_OWTRIs the eighth step in the map values of FIG.
Bias value D obtained in step L8 _TW(T_WOTR= Ma
Top value + D_TW), But D_TWIs the eighth stage
Since the value is set as a negative value in step L8, the ninth step
In step L9, the value reduced from the map value in FIG.
Water temperature T_OWTRIs set as

When it is determined at the seventh step L7 that knocking has not occurred, at a tenth step L10,
The bias value D _TW of the target outlet water temperature is (D _TW = D _TW + X _D3 )
It is calculated according to the following arithmetic expression. Here, X _D3 is, for example, once C. In the next eleventh step L11, the target outlet water temperature T _OWTR is _changed to the map value in FIG.
The value is set as a value obtained by adding the bias value D _TW obtained at 0 (T _WOTR = map value + D _TW ). Since D _TW is added, for example, once every C in the tenth step L10, the target outlet water temperature is set. T _WOTR will gradually return to the map values of FIG.

In the twelfth step L12, the bias value D
It is determined whether or not _TW is _equal to or greater than “0”. If D _TW ≧ 0, the flag F is set to “0” in a thirteenth step L13.
Is set to

According to the knock determination mode subroutine, when knocking occurs, the target outlet water temperature T _WOTR is reduced from the map value by, for example, 5 degrees C at the initial _{stage, and then} is reduced until knocking no longer occurs. 3
The target outlet water temperature T _WOTR is subtracted from the map value while increasing by degrees C, and when knocking is eliminated, the target outlet water temperature T _WOTR is subtracted from the map value while decreasing the reduction amount by, for example, 1 degree C. When the reduction amount becomes "0" (when the target outlet water temperature _TWOTR returns to the map value), the flag F is set to "0" and the control returns to the normal control mode.

[0033] FIG. 8 shows a subroutine after stopping mode, the engine outlet water temperature T _WO as in the first step N1 parameter, is read in the atmospheric pressure P _A and the radiator water temperature T _WR, operation range in the second step N2 Is searched. That is, as shown in Figure 9, operation range and non-operation range is in accordance with the atmospheric pressure P _A and the engine outlet water temperature T _WO,
Hysteresis region therebetween are set in advance so as to have a (region indicated by hatching in FIG. 9), higher engine outlet water temperature T _WO is, and the atmospheric pressure P _A is set to a low (i.e., high altitude running) state Whether it is in the operating area is the next third
The operation of the water pump 4 is stopped in a fourth step N4 when it is determined in the step N3 that it is in the non-operating range, and the third step N is performed when it is determined that it is in the operating range.
The process proceeds from step 3 to a fifth step N5.

In a fifth step N5, the duty ratio D _O 'of the motor in the water pump 4 is searched according to a map set in advance as shown in FIG. 10 according to the engine outlet water temperature T _WO . Thus, the duty ratio D _O ′ is
When the engine is stopped, the engine outlet water temperature _TWO is set so as to continuously decrease as the engine coolant temperature increases.
After the engine is stopped so that the control value in the open loop control of the water pump 4 is changed continuously in accordance with the engine outlet water temperature T _WO.

In the sixth step N6, the flow control valve 3 is forcibly opened, and most of the cooling water heated in the engine body E flows through the radiator R.

In a seventh step N7, the radiator water temperature T
_It is determined whether _WR has become _{equal to} or higher than a preset set water temperature T _WRO . The set water temperature T _WRO is determined by the radiator R
Radiator fan 11 attached to the fan switch 1
2 is set to be higher than the temperature operated.
When T _WR <T _WRO , the ninth step N9
To the eighth step N when T _WR ≧ T _WRO
Then, the processing proceeds to a ninth step N9 via the control unit 8.

In an eighth step N8, the switching valve 5 (see FIG. 1) allows the cooling water to flow through the pipe 6 having the heater unit 8, and activates the fan 13 attached to the heater unit 8. To That is, even if the radiator fan 11 is operated, the radiator water temperature T
_{When the WR} does not decrease, a part of the cooling water is caused to flow to the heater unit 8 and the fan 13 promotes heat radiation from the cooling water.

In the ninth step N9, the fifth step N5
The motor of the water pump 4 is controlled in an open loop by using the duty ratio D _O 'obtained as described above as a control value.

FIG. 11 shows a control procedure set by the control means 14 to control the operation of the flow control valve 3 in the engine operating state. In the first step M1, the engine speed N is set as a parameter. _E , engine intake pressure P
_B , the engine inlet water temperature _TWI and the radiator water temperature _TWR are read. Next, at the second step M2, in advance according to the engine speed N _E and the engine intake pressure P _B 12
The target inlet water temperature T according to the map set as shown by
_WITR is searched. In FIG. 12, the target inlet water temperature T _WITR1 is, for example, 110 ° C., the target inlet water temperature T _WITE2 is, for example, 80 ° C.
_WITR3 is, for example, 60 degrees C.

In the third step M3, the flow control valve 3
Gain K in feedback control _VCIs the engine inlet water
Warm T_WIAnd radiator water temperature T_WRIs calculated according to.
That is, as shown in FIG._WRYou
And engine inlet water temperature T_WIWater temperature difference (T_WR-T_WIRespond to
Just gain K_VCAre set in advance, and FIG.
Tte gain K_VCIs obtained.

In the fourth step M4, the feedback control opening _VCMD of the flow control valve 3 is calculated. That is,
An arithmetic expression of V _CMD = K _VC · (T _WI −T _WITR ) is executed, and in the next fifth step M5, the opening of the flow control valve 3 is controlled according to the feedback control opening V _CMD .

Next, the operation of this embodiment will be described. When the engine outlet water temperature T _WO does not reach the reference water temperature T _WS in the warm-up state of the engine, the engine outlet water temperature T _WO
Since the motor of the water pump 4 is controlled in an open loop by the fixed duty ratio D _O determined according to _WO and the engine intake pressure P _B, outlet water temperature detected due to a small amount of cooling water flowing through the engine body E Even if the value detected by the heater 15 becomes inaccurate, the cooling water temperature of the engine body E can be appropriately controlled. In addition, when the engine outlet water temperature T _WO corresponds to the allowable minimum capacity of the water pump 4 that guarantees substantially uniform flow of the cooling water in the engine body E in a low temperature state of 20 ° C. or less, the duty ratio D _O is For example, it is set to a low value of about 5%, and a substantially small amount of cooling water flows to the engine main body E while guaranteeing substantially even distribution of the cooling water in the engine main body E.
The cooling water temperature can be rapidly raised to the reference water temperature T _WS by making the temperatures of the respective parts substantially equal, and there is no local distortion or overheating of the engine body E. At this time, the flow control valve 3 is closed, and the cooling water does not pass through the radiator R but flows through the bypass circuit 2.

When the engine is in a low load state, the target outlet water temperature _TWOTR in the feedback control of the water pump 4 is set to a relatively high value of about 130 ° C. as shown in FIG. Since the target inlet water temperature T _WITR in the feedback control 3 is set to a relatively high value of about 110 ° C. as shown in FIG. 12, the cooling water temperature in the engine body E is maintained at a relatively high level, and the cooling loss It is possible to reduce fuel consumption by reducing fuel consumption and improving atomization of fuel, thereby avoiding deterioration of exhaust gas properties.

Further, the amount of cooling water circulated by the water pump 4 can be controlled to a minimum level that does not cause boiling in the engine main body E, and the upstream of the water pump 4 can be controlled regardless of the opening of the flow control valve 3. Since the pressure is not reduced on the side, boiling does not occur in the cooling water circulation circuit 1.

By the way, when the engine is in a high load state, there is an optimum value of the cooling water temperature as shown in FIG. 14 in order to reduce the fuel consumption, and also from FIG. As shown, there is an optimum value of the cooling water temperature, but the capacity of the water pump 4 is controlled according to the engine outlet water temperature _TWO , and the flow control valve 3 is set to the engine inlet water temperature TWO.
By controlling according to the _WI , it is possible to optimally control the cooling water temperature in the engine body E from the viewpoint of reducing fuel consumption, avoiding occurrence of knocking, and improving engine output.

Moreover, feedback control of the flow control valve 3
Gain K_VCIs the radiator water temperature T _WRAnd engine
Mouth water temperature T_WIRadiator because it can be changed according to
R and the amount of cooling water flowing through the bypass circuit 2.
Optimal control of the ratio to the amount of water rejected to suit engine load conditions
Supply cooling water with the combined water temperature to the inlet of the engine body E
It becomes possible.

Further, when the knocking detector 24 detects knocking, since so as to reduce the target value or target outlet water temperature T _WOTR in the feedback control of the water pump 4, at the time of occurrence of knocking engine inlet water temperature T _WI and the engine outlet The temperature difference between the water temperatures _TWO will be reduced. As shown in FIG. 15, when the temperature difference is reduced, knocking is less likely to occur, and the knocking phenomenon once generated by the reduction of the target outlet water temperature _TWOTR can be quickly eliminated.

Further, when the engine is stopped, the operation of the water pump 4 is controlled in an open loop by a control value which continuously changes in accordance with the engine outlet water temperature _TWO. It is possible to smoothly change the amount of water circulation, to prevent the generation of heat accumulation in the engine main body E, and to prevent the boiling of the cooling water and the occurrence of poor starting when the engine is restarted.

In the above embodiment, the opening of the flow control valve 3 is controlled in accordance with the engine inlet water temperature _TWI .
A thermostat that opens at a constant water temperature may be used, in which case the sixth step N6 in the flowchart shown in FIG. 8 is not required.

[0050]

As described above, the apparatus according to the first aspect of the present invention switches the water temperature detector for detecting the engine water temperature and the feedback control and the open loop control according to the engine water temperature in accordance with the operating state of the engine. And control means for controlling the operation of the water pump, so that an appropriate amount of cooling water can be circulated to the engine body even in an operation state in which the detection value of the water temperature detector is inaccurate.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the control means performs feedback control when the engine coolant temperature is equal to or higher than a predetermined reference coolant temperature, and controls the engine coolant temperature. Since it is configured to be able to switch between open loop control when the temperature is lower than the reference water temperature, an appropriate amount of cooling water flows through the engine main body at the time of warm-up, so that warm-up can be completed quickly.

According to a third aspect of the present invention, in addition to the configuration of the second aspect, the control means includes: an open-loop control when the engine water temperature is lower than the reference water temperature; Since a control value corresponding to the allowable minimum capacity of the water pump that guarantees substantially even distribution of the cooling water is preset, the minimum necessary cooling water flows through the engine body when the engine is warmed up. Generation of thermal distortion and overheating can be prevented.

According to a fourth aspect of the present invention, in addition to the configuration of the first aspect, the control means includes an open loop of the water pump having a control value which continuously changes according to the engine water temperature when the engine is stopped. Since the control is performed, the cooling water is continuously circulated through the engine body when the engine is stopped, so that the boiling of the cooling water and the restart failure of the engine can be prevented.

[0054]

[Brief description of the drawings]

FIG. 1 is an overall system diagram of a cooling device for an engine.

FIG. 2 is a flowchart of a main routine showing a control procedure of a water pump.

FIG. 3 is a flowchart showing a subroutine of a normal mode.

FIG. 4 is a diagram showing a duty ratio setting map in open loop control.

FIG. 5 is a view showing a setting map of a target outlet water temperature.

FIG. 6 is a diagram illustrating a setting map of a reference duty ratio.

FIG. 7 is a flowchart showing a subroutine of a knock determination mode.

FIG. 8 is a flowchart illustrating a subroutine of a post-stop mode.

FIG. 9 is a diagram showing a setting map of an operation area and a non-operation area after the engine is stopped.

FIG. 10 is a diagram showing a duty ratio setting map in open loop control after the engine is stopped.

FIG. 11 is a flowchart showing a control procedure of the flow control valve.

FIG. 12 is a diagram showing a setting map of a target inlet water temperature.

FIG. 13 is a diagram showing a gain setting map.

FIG. 14 is a graph showing fuel consumption rate characteristics depending on cooling water temperature.

FIG. 15 is a diagram showing knocking ignition timing characteristics according to cooling water temperature.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cooling water circulation circuit 14 Control means 15 Outlet water temperature detector 24 Knocking detector E Engine body R Radiator

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroo Shimada 1-4-1 Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Koji Okazaki 1-4-1 Chuo, Wako-shi, Saitama (56) References JP-A-1-237315 (JP, A) JP-A-62-237024 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB name) F01P 7/16 505 F01P 3/20

Claims (4)

(57) [Claims] 1. A cooling system for an engine in which an electric water pump (4) having a variable capacity is provided on the engine inlet side of a cooling water circulation circuit (1) connecting between an engine body (E) and a radiator (R). , A water temperature detector (15) for detecting the engine water temperature, and a control means (14) for controlling the operation of the water pump (4) by switching feedback control and open loop control according to the engine water temperature according to the operating state of the engine. ). An engine cooling device, comprising: 2. The control means (14) is configured to be capable of switching between feedback control when the engine coolant temperature is equal to or higher than a predetermined reference coolant temperature and open loop control when the engine coolant temperature is less than the reference coolant temperature. The cooling device for an engine according to claim 1, wherein the cooling is performed. 3. The control means (14) further comprises a water pump (guaranteed to ensure a substantially even flow of cooling water in the engine body (E) when performing open loop control when the engine water temperature is lower than the reference water temperature. The control value corresponding to the allowable minimum capacity of (4) is set in advance.
A cooling device for the engine as described. 4. The control means (14) is configured to execute open loop control of the water pump (4) by a control value that continuously changes according to the engine water temperature when the engine is stopped. cooling equipment according to claim 1, wherein the engine.