JPH02125910A - Cooling water flow control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To continually obtain optimum cooling effect and also to improve fuel consumption and exhaust gas clarification performance by detecting the water temperature at an engine outlet portion of cooling water and outside air temperature, calculating correction heat discharging quantity according to the charge of the operational condition of an engine and controlling a flow control valve. CONSTITUTION:The intake passage 10 of a water pump 2 is connected to the lower portion of a radiator 3 via an inlet side passage 4 and a flow control valve 5, and a water jacket 7 is connected to the upper portion of the radiator 3 via an outlet side passage 6. The water jacket 7 is connected to the flow control valve 5 via a bypass passage 8. The flow control valve 5 is constructed by reciprocating a valve body 11 capable of changing the opening and closing condition between the inlet side passage 4 and the bypass passage 8 to mutually contrary condition by a close coupled stepping motor 12 The stepping motor 12 is controlled by a control unit according to corrected heat discharging volume set based on the deviation between a target water temperature according to operational condition and the cooling water temperature at the outlet of the engine by a water temperature sensor 19.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] <Industrial Field of Application> The present invention relates to a cooling water flow rate control device for an internal combustion engine having a flow rate control valve for controlling the flow rate of engine cooling water.

<Prior art> Generally, in an automobile engine, a thermostat is provided at the engine side outlet or intake section of the cooling water passage that communicates the water jacket and radiator in the engine. The thermostat closes the cooling water passage to prevent cooling water from flowing to the radiator and promote warm-up, and after warming up, the cooling water passage is opened to circulate the cooling water through the radiator to prevent overheating. That's what I do. This thermostat uses thermowax as a temperature-sensitive member, and the valve body is operated by the expansion and contraction of the thermowax, but it can only be controlled in two positions, open and closed, making it difficult to control with high precision. be.

By the way, when the load is light, the amount of water circulating to the radiator is kept relatively small to reduce heat loss and purify the exhaust gas, and when the load is high, the amount of water circulating to the radiator is reduced to improve the intake efficiency. It is preferable to use a relatively large amount of cooling water, and it is desirable to change the circulating amount of cooling water depending on the operating condition. For example, Japanese Patent Application Laid-Open No. 59-226225 uses a negative pressure driven flow rate control valve and a water temperature sensor provided separately from the control valve to set a target value based on the engine speed and intake negative pressure as operating conditions. Recall the water temperature from the data map,
A system has been disclosed in which the valve opening degree is feedback-controlled so that the target water temperature matches the cooling water temperature detected by the water temperature sensor.

However, according to the structure described in item 1, a water temperature sensor is installed at the engine inlet of the cooling water, making it difficult to control the maximum temperature of the cooling water inside the engine, and it is difficult to control the maximum temperature of the cooling water in the engine due to changes in the cooling water temperature due to changes in operating conditions. Therefore, it is difficult to perform optimal control. In addition, since the control is performed regardless of the outside temperature, it is not possible to accurately control for differences in outside temperature, and since feedback control is performed, for example, when cooling water flows into the heater core of an air conditioner, There is a risk that a response delay may occur due to temperature changes.

<Problems to be Solved by the Invention> In view of the problems of the prior art, the main object of the present invention is to provide a cooling water flow rate control device for an internal combustion engine that can always perform optimal control according to the operating state of the engine. Our goal is to provide the following.

[Structure of the Invention] <Means for Solving the Problems> According to the present invention, the present invention provides a flow control valve interposed in a cooling water passage that communicates an engine and a radiator;
means for detecting the temperature of the cooling water at the outlet of the engine; means for detecting the operating state of the engine; means for detecting outside air temperature; and means for setting a target water temperature based on the detection result of the operating state. and means for setting a corrected amount of heat radiation based on the deviation between the cooling water temperature and the target water temperature, and an opening degree of the flow rate control valve based on the detection result by each of the detection means in order to achieve the corrected amount of heat radiation. This is achieved by providing a cooling water flow rate control device for an internal combustion engine characterized by having means for controlling.

In particular, it is preferable that the corrected heat radiation amount setting means includes means for compensating for the influence of the operating state of the air conditioner using the cooling water as a heat source on the corrected heat radiation amount.

<Operation> In this way, it is possible to calculate the corrected heat radiation amount according to changes in the operating state of the engine, and control the opening degree of the flow control valve to achieve the corrected heat radiation amount. The amount of circulation can be feedforward controlled according to changes in operating conditions. Further, by compensating for the influence on the corrected heat radiation amount when the air conditioner is activated, a delay in control response due to the operation of the air conditioner does not occur.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an overall view schematically showing a cooling water flow rate control device for an engine to which the present invention is applied. They communicate with each other via a side passage 4 and a flow control valve 5.

A water jacket 7 is formed in the engine 1 to allow the cooling water discharged by the water pump 2 to pass through each part of the engine 1. The water jacket 7 and the upper part of the radiator 3 are connected through an outlet passage 6. are connected to each other.

The water jacket l-7 also communicates with the flow rate control valve 5 via the bypass passage 8, and when the flow rate control valve 5 operates in the direction of closing the artificial side passage 4, the water jacket 7 is cooled. Water is allowed to circulate through the bypass passage 8 as shown by the arrow shown by the imaginary line in the figure, and when the inlet passage 4 is fully opened by the flow rate control valve 5, the bypass passage 8 becomes fully closed and circulates as shown by the arrow shown by the solid line in the figure. Note that the cooling water in the water jacket 7 is also circulated through the heater core 9 for heating, and when the heater or near conditioner is operated, the cooling water in the water jacket 7 is circulated as shown in the figure. It flows inside the heater core 9 as shown by the broken line arrow.

As clearly shown in FIG. 2, the flow control valve 5 includes a valve chamber 14 provided between the artificial side passage 4 and the suction passage 10, and a valve chamber 14 provided between the artificial side passage 4 and the bypass passage 8 as described above. The valve body 11 is comprised of a valve body 11 that can be set to opposite opening and closing states, and a direct-acting stepping motor 12 for linearly reciprocating the valve body 11. That is, the valve body 11 is fixed to the tip of the drive shaft 16 of the stepping motor 12, and the threaded portion formed at the base of the drive shaft 16 and the internal threaded portion of the rotor 13 are screwed together. As the rotor 13 rotates forward and backward, the drive shaft 16 reciprocates in the axial direction. Note that the stepping motor 12 is of a so-called hybrid type that can obtain high torque.

The valve body 11 also includes a radiator 3 when the inlet passage 4 is fully opened, as shown by the imaginary line in FIG.
Abnormal pressure can be released when the internal pressure on the side increases abnormally (=
A sub-valve body 15 is provided which is spring biased in the valve closing direction with J force. That is, when the internal pressure on the radiator 3 side increases beyond the spring biasing force of the sub-valve body 15, the sub-valve body 15 opens, so that the cooling water in the inlet side passage 4 is sucked through the valve body 11. It can flow to the passage 10 side.

The stepping motor 12 described above is driven by an output signal from the control device 17 as shown in FIG.
In this device, the fully open state of the inlet side passage 4 is the initial state of the flow rate control valve 5, and for example, when the ignition is turned on, the valve body 11 is moved in a direction to fully open the artificial side passage 4. The stepping motor 12 is rotated. For example, a limit switch type position sensor 18 is provided at the rear end of the stepping motor 12, and when the rear end of the drive shaft 16 hits the position sensor 18, a signal is sent to the control device 17, and the valve body is activated. The initial position is 11.

Further, a water temperature sensor 19 for detecting the cooling water temperature is provided at the outlet portion of the water jacket 7 facing the outlet side passage 4, an intake temperature sensor 20 for detecting the intake air temperature as the outside air temperature, and an engine A negative pressure sensor 21 that detects intake negative pressure to detect the operating state of 1 is provided in each intake pipe (not shown), and a rotation sensor of a known type that detects the engine rotation speed to similarly detect the operating state. 22 is provided in the engine 1,
A detection signal is sent to the control device 17, respectively. Further, a signal is input to the control device 17 to detect that cooling water has flowed into the heater core 9 by turning on a heater or a near conditioner (not shown).

FIG. 3 shows the flow of the processing program performed by the control device 17. First, in ST1, the valve body 11 is
Stepping motor 1 according to the amount of movement from the initial position of
After reading the current step number S of 2, in ST2, the engine rotation speed Ne detected by the rotation sensor 22 and the intake negative pressure pb detected by the negative pressure sensor 21 are read, and further in ST3, the outside air temperature detected by the intake temperature sensor 20 is read. The temperature Ta and the cooling water temperature Tw measured by the water temperature sensor 19 are read. Next ST4
In step ST2, the target water temperature To is looked up from the data stored in the pattern shown in FIG. 4, based on the engine speed Ne and intake negative pressure pb read in ST2. Then, in ST5, the cooling water temperature Tw read in ST3 is compared with the target water temperature To called out in ST4, and if T w < To, the temperature is being warmed up, the process proceeds to ST6, and S
At T6, the temperature deviation t1 is calculated by tl-To-Tw. In the next step ST7, a lookup is performed to determine the corrected heat radiation amount Q corresponding to the deviation t1 based on the function curve shown in FIG.

Further, in ST8, if it is determined that the heater or near conditioner is turned on and cooling water is flowing to the heater core 9, the process proceeds to ST9, and a pre-stored correction is made according to the required amount of heat dissipation by the heater core 9. Call up the heat radiation amount Qh and proceed to STI 1. Note that if it is determined in ST8 that the heater or air conditioner is off, the process proceeds to 5T10, sets the corrected heat radiation amount Qh to 0, and
Proceed to T11. In 5TII, based on the corrected heat radiation amount Q called in Sr7 and the corrected heat radiation amount Qh called in Sr1 or 5TIO, the number of correction steps ΔS according to the amount of movement of the valve body 11 in the closing direction is calculated using the following formula. Calculated by

ΔS=K (Qh Q)/Ne (Tw-Ta) The above formula is based on the fact that the amount of heat released to the cooling water of the engine 1 is proportional to the amount of circulating water in the cooling water, and the amount of circulating water is proportional to the engine speed. K in the formula is the amount of movement of the valve body 11 according to the opening degree of the flow control valve 5 in order to ensure the amount of circulating cooling water according to the corrected heat radiation amount. This is a coefficient for converting into .

Then, in 5TI2, the number of steps S after correction is calculated, and in 5T13, the stepping motor 12 is rotated by the corrected number of steps, 68.

By the way, in Sr5, if the cooling water temperature Tw is higher than the target water temperature To, proceed to 5T14, and in ST14, compare the height of the cooling water with respect to the upper limit water temperature T1, and if it is lower, proceed to 5T15. . In this 5T15, the temperature deviation t2 is t2=Tw-T.

In the next s'r16, a lookup is performed to determine the corrected heat radiation amount Q according to the deviation t2 based on the function curve shown in FIG.

Then, the process advances to Sr1, and the same processing as described above is performed thereafter.

In addition, in 5T14, if the cooling water temperature Tw is higher than the 1 limit water temperature T1, the process proceeds to 5TI7, and in 5T17, the step number S is set to 0, and the process proceeds to 5T13, in order to fully open the artificial passageway 4. The stepping motor 12 is rotated to move the valve body 11 toward the initial position.

In this embodiment, the target water temperature To called at Sr4 is divided into three regions, high temperature range, medium temperature range, and low temperature range, as shown in FIG.
and the target water temperature T according to the relative relationship between the two
o. That is, the higher the engine speed Ne is, the lower the target water temperature To is, and the higher the load is, the lower the target water temperature To is, so that it is easy to progress from Sr5 to 5T14 during high speed or high load operation. We are trying to increase the cooling capacity.

In addition, the corrected heat radiation amount Q called in Sr7 is decreased as the deviation t1 increases, as shown in FIG. 5, and is derived from a function curve that becomes a negative correction amount when the deviation t1 becomes larger. There is.

With this, for example, when starting in a cold state, it is desirable to prevent the cooling water from flowing into the radiator 3 and quickly warm it up.
need to be moved. That is, when the cooling water is cold, the temperature deviation t1 becomes large because the cooling water temperature Tw is low, and the corrected heat radiation amount Q becomes a negative value, and ΔS becomes a positive value. Therefore, the number of steps S is increased and the valve body 11 Drive in the closing direction.

On the other hand, when the engine is started when the engine is warm, the cooling water is already warmed to some extent, so it is preferable to allow the cooling water to flow through the radiator 3 in order to prevent the -L rising curve of the water temperature from overshooting. Therefore, during warm weather, the cooling water temperature Tw
Since the temperature difference t1 is high, the temperature deviation t1 becomes small, the corrected heat radiation amount Q becomes a positive value, and ΔS becomes a negative value, so the number of steps S is reduced and the valve body 11 is driven in the opening direction.

Further, the corrected heat radiation amount Q called at 5T16 is set to increase as the temperature deviation t2 increases, as shown in FIG. In this case, the engine 1 is in a warmed-up state, and it is necessary to cool the engine by flowing a large amount of cooling water into the radiator 3.

Therefore, as the cooling water temperature Tw becomes higher, the temperature deviation t
2 becomes larger, the corrected heat radiation amount Q becomes larger, and the valve body 11 is driven toward the fully open position.

In this way, depending on the level of the cooling water temperature, when the water temperature is low and the water temperature is warm up, control is performed to promote warming up, and when the water temperature is high after warming up, the cooling water flowing to the radiator is controlled to the maximum level. It is controlled so that In addition, when the temperature is within the normal temperature range after warming up, it is controlled to perform appropriate heat radiation according to the size of the load, so it is possible to reduce heat loss and purify the exhaust gas. Since so-called feedforward control is performed based on the required amount of heat radiation depending on the operating state of the engine, there is no control delay due to feedback control. In addition, the control valve has a greater degree of freedom in installation than one that uses a thermostat, and is not only easy to design, but also uses the stepping motor 12 to control the position of the valve body 11 with high precision, so that it can be placed in a half-open state. The flow rate can be controlled very accurately and easily.

Furthermore, since the responsiveness of the entire system is not so fast and in order to prevent hunting, it is sufficient to perform control with a relatively long cycle time, and for example, it is also possible to use the CPU of another control device. Furthermore, for engines whose engine control devices are equipped with sensors for cooling water temperature, intake air temperature, and intake negative pressure, there is no need to install new sensors, which has the effect of suppressing the rise in parts costs. be.

[Effects of the Invention] As described above, according to the present invention, by detecting the water temperature of the cooling water at the engine outlet and the outside air temperature, it is possible to accurately calculate the corrected heat radiation amount due to changes in the engine operating status, and the correction Since the opening degree of the flow rate control valve is controlled to achieve the amount of heat dissipation, an optimum cooling effect can always be obtained, and fuel efficiency and exhaust gas purification can be improved. Further, by compensating for the influence of the operating state of the air conditioner on the corrected heat radiation amount, the effect is extremely large, such as preventing a delay in response to temperature changes when the air conditioner is activated.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing the entire cooling water flow rate control device to which the present invention is applied. FIG. 2 is an enlarged view of the main parts of the flow control valve according to the present invention. FIG. 3 is a flow diagram showing the flow of a program for a flow rate control device based on the present invention. FIG. 4 is a diagram showing an example of a control pattern in Sr1 shown in FIG. FIG. 5 is a diagram showing an example of a control function curve at Sr7 shown in FIG. FIG. 6 is a diagram showing an example of a control function curve in 5T16 shown in FIG. 3. 1...Engine 2...Water pump 3.
...Radiator 4...Passage side passage 5...Flow rate control valve 6...Outlet side passage 7...Water jacket 8...Bypass passage 9...Heater core 10...
・Suction passage 11...Valve body 12...Stepping motor

Claims (2)

[Claims] (1) A flow control valve interposed in a cooling water passage communicating between the engine and the radiator, means for detecting the temperature of the cooling water at the outlet of the engine, and means for detecting the operating state of the engine. , means for detecting outside air temperature; means for setting a target water temperature based on the detection result of the operating state; and means for setting a corrected heat radiation amount based on the deviation between the cooling water temperature and the target water temperature; A cooling water flow rate control device for an internal combustion engine, comprising means for controlling the opening degree of the flow rate control valve based on the detection results by the respective detection means in order to achieve a corrected amount of heat radiation. (2) The internal combustion engine according to claim 1, wherein the corrected heat radiation amount setting means includes means for compensating for the influence of the operating state of the air conditioner using the cooling water as a heat source on the corrected heat radiation amount. cooling water flow control device.