JP2000045773A - Cooler for liquid-cooled internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control water temperature of a pump inlet with high accuracy without measuring a flow rate. SOLUTION: A flow ratio Vrb of a radiator flow Vr to a bypass flow Vb is determined on the basis of a pump water temperature Tp (first water temperature sensor 621), a bypass water temperature Tb (second water temperature sensor 622) and a radiator water temperature Tr (third water temperature sensor 623), and the relationship between the flow rate Vrb and a valve opening is determined in advance and mapped. In an actual cooler, the valve opening is determined based on the flow ratio Vrb and the map. Whereby the water temperature of a pump inlet can be controlled with high accuracy without detecting the flow rate.

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 a liquid-cooled internal combustion engine such as a water-cooled engine, and is effective for cooling an internal combustion engine for running a vehicle.

[0002]

2. Description of the Related Art In a liquid-cooled internal combustion engine (hereinafter, referred to as an engine), the engine is operated efficiently by suppressing a decrease in intake air charging efficiency and an increase in friction loss in movable parts in the engine. Therefore, engine cooling water (hereinafter,
Abbreviated as cooling water. ) Needs to be controlled to an appropriate temperature.

Therefore, as a cooling device for an engine, for example, in the invention described in JP-A-63-268912,
The temperature of the cooling water is controlled based on the wall temperature of the cylinder block of the engine.

[0004]

By the way, when controlling the temperature of the cooling water, the inventors have found that the flow rate flowing through the bypass circuit and the flow rate flowing through the radiator at the junction of the outlet side of the radiator and the bypass circuit. A flow control valve for controlling the flow rate of the cooling water is provided, and the valve opening of the flow control valve is set to the temperature of the cooling water at the cooling water inlet side of the engine (the cooling water inlet side of the pump). ) By feedback control.
A prototype of a cooling device that controls the inlet temperature to an appropriate temperature was studied, but it was difficult to control the inlet temperature with high accuracy for the following reasons.

That is, the inlet temperature is determined by the temperature and flow rate of the cooling water flowing out of the radiator and the temperature and flow rate of the cooling water flowing through the bypass circuit. Instead, the valve opening was controlled only by the temperature. For this reason, since the change in the flow rate due to the change in the valve opening is not reflected in the control of the flow control valve, it becomes difficult to control the inlet temperature with high accuracy.

On the other hand, the flow rate of the cooling water flowing out of the radiator and the flow rate of the cooling water flowing through the bypass circuit may be detected, and the detected flow rate may be added to the control parameters of the flow control valve. It is practically difficult to dispose instruments and sensors for flow detection in the room due to problems such as mounting space and cost. In view of the above, an object of the present invention is to accurately control an inlet water temperature without measuring a flow rate.

[0007]

The present invention uses the following technical means to achieve the above object. Claim 1
In the invention described in Item 4, the first temperature (Tp), which is the temperature of the coolant on the outlet (413) side, the second temperature (Tb), which is the temperature of the coolant flowing through the bypass circuit (300), and the radiator The opening degree of the flow control valve (400) is controlled based on the third temperature (Tr) which is the temperature of the coolant flowing out from the (200).

Thus, as described later, the flow rate control valve can be controlled by adding the flow rate to the control parameter without directly detecting the flow rate, so that the coolant at the coolant inlet of the liquid-cooled internal combustion engine can be controlled. The temperature can be controlled accurately. The opening of the flow control valve (400) is defined by claim 2
As described above, the first to third temperatures (Tb, Tr, T
p), the first temperature (Tp) is determined based on the load of the liquid-cooled internal combustion engine (100).
It is desirable to perform feedback control so that p).

According to a third aspect of the present invention, a blower (23) is provided based on the load of a liquid-cooled internal combustion engine (100).
The air volume of 0) may be controlled. Further, the discharge flow rate of the pump (500) may be controlled based on the load of the liquid-cooled internal combustion engine (100).
Incidentally, the reference numerals in parentheses of the above means are examples showing the correspondence with specific means described in the embodiments described later.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) In this embodiment, a cooling device for a liquid-cooled internal combustion engine according to the present invention is applied to a water-cooled engine for driving a vehicle (liquid-cooled internal combustion engine). FIG. 1 is a schematic diagram of a cooling device according to the present embodiment.

In FIG. 1, reference numeral 200 denotes a water-cooled engine (hereinafter, referred to as a water-cooled engine).
Engine abbreviation. ) Cooling water (cooling liquid) circulating in 100
A radiator 210 for cooling the radiator 20;
A radiator circuit for circulating cooling water to zero. 300
The cooling water flowing out of the engine 100 is supplied to the radiator 2
This is a bypass circuit that guides the cooling water to the outlet of the radiator 200 in the radiator circuit 210 by bypassing 00.

The radiator circuit 2 is connected to the junction 220 between the bypass circuit 300 and the radiator circuit 210.
10 (hereinafter, this flow rate is referred to as a radiator flow rate Vr) and the flow rate of the cooling water flowing through the bypass circuit 300 (hereinafter, this flow rate is referred to as a bypass flow rate Vb).
Call. ) And a rotary flow control valve (hereinafter, referred to as
Abbreviated as control valve. An electric pump (hereinafter, abbreviated as a pump) that operates independently of the engine 100 to circulate the cooling water downstream of the control valve 400 in the flow of the cooling water (the engine 100 side). ) 500 are provided.

Here, the schematic structure of the control valve 400 will be described. As shown in FIG. 2, the control valve 400 includes a pump housing 510 and a control valve 400.
And the valve housing 410. Incidentally, both housings 410 and 510 are made of resin.
In the valve housing 410, as shown in FIGS. 3 and 4, a cylindrical (cup-shaped) rotary valve (hereinafter abbreviated as a valve) 420 whose one end in the longitudinal direction (axial direction) is closed is rotatable. As shown in FIG. 2, the valve 420 is driven to rotate around a cylindrical axis by an actuator section 430 having a reduction gear composed of a plurality of gears 431 and a servomotor (drive means) 432.

As shown in FIG. 4, the cylindrical side surface 420a of the valve 420 has first and second conjoined shapes (in this embodiment, circular shapes having the same diameter) communicating the inside and outside of the cylindrical side surface 420a. Valve ports 421, 422
Are formed, and both valve ports 421 and 422 are
It is offset from the cylindrical axis of the valve 420 by about 90 degrees. On the other hand, in a portion of the valve housing 410 corresponding to the cylindrical side surface 420a of the valve 420, as shown in FIG.
Radiator port (radiator-side inlet) 411 communicating with radiator circuit 210 side, and bypass circuit 30
Bypass port (bypass side inlet) 4 communicating with the 0 side
12 are formed. Further, a pump port (outflow port) 413 for communicating the inside 420b of the cylinder of the valve 420 with the suction side of the pump 500 is provided at a portion of the valve housing 410 corresponding to the other end of the valve 420 in the cylindrical axis direction. Is formed.

Reference numeral 440 denotes a cylindrical side surface 4 of the valve 420.
A gap between the inner wall of the valve housing 410 and the radiator port 411 and the bypass port 41 is sealed.
2 is a packing for preventing the cooling water flowing into the valve housing 410 from flowing into the pump port 413 by bypassing the cylindrical inside 420 b of the valve 420. As shown in FIG. 2, a potentiometer (opening detecting means) 4 for detecting the rotational angle of the valve 420 (the opening of the control valve 400) is provided on the rotating shaft 423 of the valve 420.
The detection signal of the potentiometer 424 is input to an ECU 600 described later.

Reference numeral 600 denotes a control valve 400 and a pump 5
00 is an electronic control unit (ECU). The ECU 600 includes a pressure sensor (pressure detecting means) 610 for detecting a suction negative pressure of the engine 100, and first to third water temperature sensors (temperature detecting means) 621 for detecting the temperature of the cooling water.
623 and a detection signal from a rotation sensor (rotation speed detecting means) 624 for detecting the rotation speed of the engine 100, and the ECU 600 performs the following based on these signals.
The control valve 400, the pump 500, and the blower 230 are controlled.

Here, the first water temperature sensor 621 detects the temperature of the cooling water flowing into the pump 500 (engine 100) at the pump port 413 side (hereinafter, this temperature is referred to as the pump water temperature Tp).
Call. ), The second water temperature sensor 622 detects the temperature of the cooling water flowing through the bypass circuit 300 on the bypass port 412 side, that is, the temperature of the cooling water flowing out of the engine 100 (hereinafter, this temperature is referred to as a bypass water temperature Tb). ) Is detected, and the third water temperature sensor 623 detects the radiator port 41.
On the first side, the temperature of the cooling water flowing out of the radiator 200 (hereinafter, this temperature is referred to as a radiator water temperature Tr) is detected.

Next, the operation of this embodiment will be described with reference to the flowchart shown in FIG. When the engine 100 is started after an ignition switch (not shown) of the vehicle is turned on, the detection values of the sensors 610, 621 to 624 are read (S100). Then, the engine load is calculated from the rotation speed of the engine 100 and the suction negative pressure. Based on the calculated engine load, a basic cooling water flow rate (the rotation speed of the pump 500) circulating in the engine 100 is calculated from a map (not shown). Target engine 10
The temperature of the cooling water flowing into 0 (hereinafter, this water temperature is referred to as a target water temperature Tmap) is determined (S110).

The target water temperature Tmap is determined such that the water temperature when the engine load is small is higher than the water temperature when the engine load is large. Next, it is determined whether or not the pump water temperature Tp is within a predetermined range based on the target water temperature Tmap (in this embodiment, a range of ± 2 ° C. based on the target water temperature Tmap) (S120).
When p is within a predetermined range based on the target water temperature Tmap, the current opening of the control valve 400 (hereinafter, the opening of the control valve 400 is referred to as a valve opening) is maintained (S130), and S
Go back 100.

On the other hand, when the pump water temperature Tp is out of the predetermined range based on the target water temperature Tmap, the difference ΔT (Tmap-Tp) between the target water temperature Tmap and the pump water temperature Tp is shown in FIGS. According to the map, the valve opening amount to be changed from the current valve opening, the flow rate to be changed from the current cooling water flow rate (basic cooling water flow rate), and the air blowing amount to be changed from the current air blowing amount are determined (S14).
0). At this time, the valve opening, the flow rate of the cooling water, and the air flow rate are determined so that the power consumption of the pump 500 and the power consumption of the blower 230 are minimized.

The map of FIG. 5 shows that the rotation speed of the pump 500 increases as the duty of the pump 500 increases, and the map of FIG. 6 shows that the rotation speed of the blower 230 increases as the duty of the blower 230 increases. Are higher, and both duty factors are determined based on the engine load such that the power consumption of the pump 500 and the power consumption of the blower 230 are minimized as described above.

Then, a control signal is issued so that the operating states of the control valve 400, the pump 500 and the blower 230 become the determined values (S150). And the control valve 400 is repeated by repeating the control from S100 to S150.
Feedback control. Next, features of the present embodiment will be described. Since the pump water temperature Tp is determined by mixing the cooling water flowing through the bypass circuit 300 and the cooling water flowing through the radiator 200, it is necessary to accurately control the pump water temperature Tp to be the target water temperature Tmap. As described in the section "Problems to be Solved by the Invention", it is necessary to detect the radiator flow rate Vr and the bypass flow rate Vb in addition to the radiator water temperature Tr and the bypass water temperature Tb.

However, it is practically difficult to accurately measure the flow rate of the cooling water circulating in the cooling device, as described above. Therefore, in the present embodiment, as described below, the radiator flow rate Vr and the bypass flow rate Vb, that is, the valve opening, are determined based on the pump water temperature Tp, the radiator water temperature Tr, and the bypass water temperature Tb. As described above, the pump water temperature Tp is determined by mixing the cooling water flowing through the bypass circuit 300 and the cooling water flowing through the radiator 200.

[0024]

Tp = (Tr.Vr + Tb.Vb) / (Vr + Vb) Here, the flow rate ratio Vrb between the radiator flow rate Vr and the bypass flow rate Vb is defined as in Expression 2.

[0025]

## EQU2 ## If VrbbVr / Vb, Equation 1 is transformed into Equation 3.

[0026]

## EQU3 ## Tp = (Tb + Tr.Vrb) / (1 + Vrb) Further, from Expression 3, Vrb becomes Expression 4.

[0027]

Vrb = (Tb−Tp) / (Tp−Tr) Here, the valve opening is determined by the flow rate ratio Vrb as shown in FIG.
Therefore, if the flow rate ratio Vrb is obtained, the valve opening can be uniquely determined. Incidentally, the relationship between the flow ratio Vrb and the valve opening shown in FIG. 7 was confirmed by a test.

The flow ratio Vrb can be calculated based on the pump water temperature Tp, the radiator water temperature Tr, and the bypass water temperature Tb, as is apparent from Equation 4. Here, if the target flow ratio Vrb is calculated using the pump water temperature Tp in Expression 4 as the target water temperature Tmap, the target flow ratio Vrb becomes Expression 5. Hereinafter, the flow rate ratio V determined by Expression 4
rb is called an actual flow ratio Vrb.

[0029]

Vrb = (Tb-Tmap) / (Tmap-Tr) Therefore, the target valve opening determined from the target flow ratio Vrb and FIG. 7, and the actual valve opening determined from the actual flow ratio Vrb and FIG. From the difference from the degree, the valve opening amount to be changed from the current valve opening degree, that is, the map shown in FIG. 5 is determined.

As described above, according to this embodiment, if the pump water temperature Tp, the radiator water temperature Tr, and the bypass water temperature Tb are known, the valve opening can be accurately determined without measuring the actual cooling water flow rate. can do. In addition,
In the above description, the pump water temperature Tp is
0 and the state of the cooling water that has passed through the radiator 200, but it is actually determined that the water temperature is detected by the first to third water temperature sensors 621 to 623 at different times. Therefore, a difference may occur between the actual coolant temperature and the detected coolant temperature during the time lag. Therefore, when mounting the first to third water temperature sensors 621 to 623, it is desirable to bring the first to third water temperature sensors 621 to 623 as close as possible.

When the engine load increases and the target water temperature Tmap decreases, the valve opening is changed to increase the radiator flow rate Vr as described above. However, the radiation capacity of the radiator 100 with respect to the variation in the radiator flow rate Vr is increased. As is well known, the amount of change (increase change rate of the heat radiation capability) decreases as the radiator flow rate Vr (flow velocity in the radiator 200) increases.

For this reason, even if the radiator flow rate Vr is increased in order to lower the pump water temperature Tp, the heat radiation capacity does not increase as compared with the increase in the radiator flow rate Vr, so that it is necessary to circulate the cooling water to the radiator 200. The ratio of the cooling capacity to the pump work (power consumption of the pump 500) of the pump 500 decreases, and unnecessary pump work increases.

On the other hand, in the present embodiment, the amount of air blown by the blower 230 is also controlled based on the engine load. Can be increased, and unnecessary pump work can be prevented from increasing.
FIG. 8A shows the pump water temperature Tp when the air flow rate is increased in accordance with the increase in the engine load (solid line) and the pump water temperature when the air flow rate is not increased in accordance with the increase in the engine load (dashed line). 4 is a graph showing Tp.

As is apparent from FIGS. 8A and 8B, when the air flow is increased according to the increase in the engine load, the air flow is not increased according to the increase in the engine load. Even if the valve opening is made smaller and the radiator flow rate Vr is reduced, the pump water temperature Tp and the pump 5
It can be seen that the power consumption of 00 is reduced. By the way, in general, when the vehicle is running, the flow velocity of the traveling wind passing through the radiator 200 is as small as about 10% of the flow velocity of the traveling wind. Therefore, when the vehicle speed is low as on an uphill and the engine load is large, It is difficult to cool the cooling water only by the traveling wind.

However, in this embodiment, when the engine load is large, the blower volume is increased by the blower 230. Therefore, when the engine load is large, the cooling water temperature (pump water temperature Tp) can be reliably reduced. . Therefore, the cooling water temperature can be controlled to an appropriate temperature according to the engine load. By the way, in the above embodiment, three water temperatures (pump water temperature Tp, radiator water temperature Tr
Although the three water temperature sensors 621 to 623 are used to detect the bypass water temperature Tb), the second water temperature sensor 622 for detecting the bypass water temperature Tb is eliminated, and the bypass water temperature Tb and the radiator water temperature Tr are used. May be estimated. Hereinafter, a method of estimating the flow ratio Vrb when the second water temperature sensor 622 is abolished will be described.

That is, from the equation (4), the bypass water temperature Tb becomes the equation (6).

[0037]

Tb = Tp + (Tp-Tr) .Vrb Here, the flow rate ratio Vrb can be uniquely obtained from the valve opening as shown in FIG. The opening degree is obtained, and the bypass water temperature Tb can be estimated from the obtained valve opening degree.

In the above-described embodiment, the maps shown in FIGS. 5 and 6 are values determined on the assumption that the outside air temperature is 25 ° C., so that S140 is set between S140 and S150.
It is preferable to provide a correction step for correcting the value of the stagnation.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a cooling device.

FIG. 2 is an external view of an integrated control valve and pump.

3A is a sectional view taken along line AA of FIG. 2, and FIG. 3B is a sectional view taken along line BB of FIG. 3A.

FIG. 4 is a control flowchart of the cooling device.

FIG. 5 is a control map of the pump.

FIG. 6 is a control map of the blower.

FIG. 7 is a graph showing a relationship between a valve opening degree and a flow rate ratio.

8A is a graph showing a relationship between an engine load and a pump inlet side water temperature, FIG. 8B is a graph showing a relationship between an engine load and a valve opening, and FIG. It is a graph showing the relationship with pump power consumption,
(D) is a graph showing the relationship between the engine load and the power consumption of the blower, and (e) is a graph showing the relationship between the engine load and the vehicle speed.

[Explanation of symbols]

100: engine (liquid-cooled internal combustion engine), 200: radiator, 230: blower, 300: bypass circuit, 400
... Rotary flow control valve, 500 ... Electric pump, 600
… Electronic control unit, 610 pressure sensor, 621 first water temperature sensor, 622 second water temperature sensor, 623 third water temperature sensor.

Claims (4)

[Claims] A radiator (2) that cools a coolant flowing out of a liquid-cooled internal combustion engine (100), and then flows the cooled coolant toward the liquid-cooled internal combustion engine (100).
00), and a bypass circuit (300) for leading the coolant flowing out of the liquid-cooled internal combustion engine (100) to the radiator (200) by bypassing the radiator (200).
A bypass-side inlet (412) through which the coolant flowing through the bypass circuit (300) flows, and the radiator (20).
0), a radiator-side inlet (411) into which the coolant flowing out from the inlet and an outlet (413) through which the flowing coolant flows out toward the liquid-cooled internal combustion engine (100). A flow control valve (400) for controlling a bypass flow rate (Vb) of the coolant flowing through the radiator (200) and a radiator flow rate (Vr) of the coolant flowing through the radiator (200); ) Side, the first temperature (Tp) which is the temperature of the coolant, the second temperature (Tb) which is the temperature of the coolant flowing through the bypass circuit (300), and the temperature of the coolant flowing out of the radiator (200). A cooling device for a liquid-cooled internal combustion engine, wherein an opening degree of the flow control valve (400) is controlled based on a third temperature (Tr) which is a temperature. 2. The opening degree of the flow control valve (400) is determined based on the first to third temperatures (Tb, Tr, Tp) based on the first temperature (Tp) and the liquid-cooled internal combustion engine (100). 2. The feedback control is performed so that the target water temperature (Tmap) is determined based on the load of (1).
3. The cooling device for a liquid-cooled internal combustion engine according to claim 1. 3. A blower (230) that blows air to the radiator (200), and controls a blowing amount of the blower (230) based on a load of the liquid-cooled internal combustion engine (100). The cooling device for a liquid-cooled internal combustion engine according to claim 1 or 2, wherein: 4. A pump (500) that operates independently of the liquid-cooled internal combustion engine (200) and circulates a cooling liquid, and the pump based on a load of the liquid-cooled internal combustion engine (100). The cooling device for a liquid-cooled internal combustion engine according to any one of claims 1 to 3, wherein a discharge flow rate of (500) is controlled.